LPN IV Series: IV Pharmacology

Inhibits Vitamin K synthesis, which impacts Factors VII, IX, X, and II. At a therapeutic level, warfarin inhibits the liver's production of vitamin K, which creates the therapeutic range. Although therapeutic ranges may be achieved in 1-2 hours, the full effect is not achieved for 4-5 days until Factor II is depleted (Edmunds & Mayhew, 2013). It is important to draw the INR on time and before administering the medication. The INR is one way to determine the dose of the medication. INR is typically checked every three days until the therapeutic range is achieved. The INR is checked periodically. INR should also be checked seven days after starting or changing the dose of a new medication (Nursing, 2016).

Warfarin has a black box warning as it can cause major bleeding. Bleeding is more likely to occur during the start of the treatment. It is important to monitor INR carefully and complete a full assessment of the patient (Nursing, 2016). Warfarin also interacts with several other medications and foods. Be sure to check all medications for interactions, assess the patient's diet, and ask about any herbals or vitamins taken.

Warfarin can be given IV.

Warfarin may impact other laboratory tests (Nursing, 2016)

Foods and supplements that impact warfarin

• Grapefruit and Cranberry products
• Green leafy vegetables must be kept consistent in the diet
• Garlic
• Ginger
• Gingko Biloba
• Feverfew
• Fish oil
• Turmeric
• St John's Wort
• Chondroitin sulfate
• Vitamin supplements

Assess alcohol intake and vegetable intake, especially vegetables high in vitamin K such as kale, parsley, collards, spinach, turnip greens, mustard greens, collard greens and beet greens.

Unfractionated heparin (UFH) is an older form that has been used in clot prevention for many years. It is usually used in the hospital setting to treat acute issues such as DVT, PE, MI, stroke, or atrial occlusion. This treatment can also be given prophylactically prior to surgery. Check with your institution as to the proper procedural use. Side effects are more significant with UFH and include an increased chance of bleeding and pain, and bruising at the injection site. Patients will usually get switched to an LMWH due to the high side effect profile of UFH. Monitoring aPTT begins 3-4 hours after initiation, and doses are adjusted accordingly (Edmunds & Mayhew, 2013).

Heparin and LMWH can be given IV. Heparin is usually started with an IV push bolus followed by a continuous infusion. The dosage will vary based on the condition being treated and the weight of the patient.

Remember that warfarin (Coumadin) takes several days to reach therapeutic concentration. It is important to remember to start warfarin prior to discontinuing heparin therapy. Warfarin is gradually adjusted until the INR of 2:3 is reached. The target range may be higher for certain disorders (Edmunds & Mayhew, 2013).

Nursing Considerations for Heparin:

• SQ Inject between iliac crests in the lower abdomen into the fat layer.
• Do not massage the area.
• Alternate sites every 12 hours.
• Draw blood for PTT 4-6 hours after administration (Therapeutic level is 1 ½- 2 ½ times the baseline).
• Monitor platelet count.
• Assess patient for bruising, bleeding, petechiae, nosebleed, melena, tarry stool, hematuria, and hematemesis.
• Monitor for agranulocytosis, leukopenia, eosinophilia, thrombocytopenia, tissue irritation and sloughing, and site reactions. Patients should be monitored for signs and symptoms of hemorrhage, like a drop in BP or rapid pulse.
• Monitor vital signs.
• Do not check for blood return.
• Apply gentle pressure for 5-10 seconds.

Patient Education

• Instruct patient or caregiver to watch for bleeding or bruising
• Avoid OTC medications containing aspirin or salicylates
• Avoid herbal supplements
• Encourage smoking cessation as nicotine decreases the effect of heparin
• Monitor CBC in menstruating females (May see excessive bleeding)
• Use a soft toothbrush
• Use an electric razor
• Wear identification stating the use of heparin

ACE Inhibitors work by interrupting the conversion of renin-angiotensin I to angiotensin II. This drug causes dilation of the arterial and venous vessels and blood pressure drops.

Common ACE inhibitor agents include:

• Benazepril (Lotensin)
• Captopril (Captopril)
• Enalapril (Vasotec)
• Fosinopril (Monopril)
• Lisinopril (Prinivil, Zestril)

Ace inhibitors are absorbed in the gut and metabolized mostly in the liver. The kidneys excrete these medications. Careful monitoring of renal function and liver stability is imperative. Ace inhibitors stop the conversion of angiotensin I into becoming angiotensin II (Woo & Wynne, 2011). Angiotensin II is a peripheral vasoconstrictor that causes the excretion of aldosterone, which causes sodium and water retention. If angiotensin II is not allowed to work, peripheral vascular resistance is reduced, and the lack of aldosterone promotes sodium and water excretion. This action reduces the amount of blood going through the heart, which will reduce blood pressure (Edmunds & Mayhew, 2013).

Ace inhibitors can be used in conjunction with other medications to treat hypertension. Most commonly, they are prescribed beta-adrenergic blockers or diuretics. Some Ace inhibitors such as lisinopril and captopril are also used in heart failure in certain instances, particularly for left ventricular dysfunction, to improve mortality and morbidity (Edmunds & Mayhew, 2013).

Enalapril (Vasotec) initial IV dose is 1.25 mg/dose, given over 5 minutes every 6 hours; doses as high as 5 mg/dose every 6 hours have been tolerated for up to 36 hours.

Nursing Considerations

1. These medications can become less effective when used with NSAIDs and antacids.
2. Ace inhibitors enhance the hypotensive effect of diuretics, and beta-adrenergic blockers.
3. They can increase serum lithium levels.
4. Food decreases absorption of Ace inhibitors.
5. Adverse reactions include: headache, fatigue, GI reactions, cough, and throat irritation are the most common.
6. Ace inhibitors can also cause an increase in serum potassium and an elevation of BUN and creatinine levels.
7. Monitor vital signs regularly.
8. Check for adverse reactions.
9. Monitor weight, electrolytes and fluid status.
10. Instruct the patient to take with food or at bedtime.
11. Instruct the patient to get up slowly as orthostatic hypotension can occur when rising.
12. Help the patient maintain a diet and exercise program.

Several medication interactions can occur. Care should be taken to review all medications taken with Ace inhibitors. For example, NSAIDs reduce the medication's effectiveness, potassium supplements cause hyperkalemia, and lithium levels may be increased when taken with Ace inhibitors (Woo & Wynne, 2011).

B-adrenergic (beta) blockers reduce blood pressure by blocking the effects of epinephrine. This blocker helps the heart relax. The beats slower, the left ventricle fills more completely, vessels become more open, and the heart uses less force to work (Woo & Wynne, 2011). Cardiac output is reduced, causing a decrease in peripheral vascular resistance and a decrease in renin activity (Zisaki et al., 2015).

Common agents include:

• Acebutolol (Sectral)
• Atenolol (Tenormin)
• Metoprolol (Lopressor)
• Labetalol (Trandate)
• Propranolol (Inderal)
• Bisoprolol (Zebeta)
• Nadolol (Corgard)

Beta-blockers are, for the most part, absorbed in the GI tract, metabolized by the liver and excreted through the renal system. Some beta-blockers, such as propranolol and metoprolol, are more highly bound to protein than the others in this class (Zisaki et al., 2015).

It is important to note that several medications interact with beta-blockers:

• Antacids can delay absorption
• NSAIDs can decrease the hypotensive effects
• Lidocaine toxicity can occur
• Diabetic medications may need to be altered

Also, adverse reactions include bradycardia, angina, heart failure, arrhythmias, fainting, fluid retention, peripheral edema, nausea and vomiting, diarrhea, and difficulty breathing due to bronchiole constriction (Nursing, 2016).

Atenolol (Tenormin) initial IV dosage is 1.25 to 5 mg every 6-12 hours, have been used in the short-term management of patients unable to take oral tabs. MI early treatment: 5 mg slow IV over 5 minutes; may repeat in 10 minutes. If both doses are tolerated, may start oral atenolol 50 mg every 12 hours or 100 mg/day for 6-9 days post-myocardial infarction. Oral: Follow IV dose with 100 mg/day or 50 mg twice daily for 6 to 9 days post-myocardial infarction (Global, 2018).

Esmolol (Brevibloc) used for supraventricular tachycardia or gradual control of postoperative tachycardia/hypertension IV loading dose: 500 mcg/kg over 1 minute; follow with a 50 mcg/kg/minute infusion for 4 minutes; response to this initial infusion rate may be a rough indication of the responsiveness of the ventricular rate. The infusion may be continued at 50 mcg/kg/minute or, if the response is inadequate, titrated upward in 50 mcg/kg/minute increments (increased no more frequently than every 4 minutes) to a maximum of 200 mcg/kg/minute (Global, 2018).

To achieve a more rapid response, following the initial loading dose and 50 mcg/kg/minute infusion, re-bolus with a second 500 mcg/kg loading dose over 1 minute, and increase the maintenance infusion to 100 mcg/kg/minute for 4 minutes. If necessary, a third (and final) 500 mcg/kg loading dose may be administered before increasing to an infusion rate of 150 mcg/minute. After 4 minutes of the 150 mcg/kg/minute infusion, the infusion rate may be increased to a maximum rate of 200 mcg/kg/minute (without a bolus dose) (Global, 2018).

Supraventricular tachycardias (SVT) IV dose range: Usual dosage range is 50-200 mcg/kg/minute with average dose of 100 mcg/kg/minute (Global, 2018).

Labetalol (Normodyne) use in hypertensive emergency dose is 20mg IV slow injection, then 40-80 mg IV every 10 minutes as needed. (up to 300 mg total dose) until desired BP is reached or start continuous infusion: 2 mg/min (range: 1 to 3 mg/min)–titrate to BP.

Metoprolol (Lopressor) use in Hypertension/ventricular rate control IV dose (in patients having nonfunctioning GI tract): Initial: 1.25-5 mg every 6-12 hours; titrate initial dose to the response. Initially, low doses may be appropriate to establish response; however, up to 15 mg every 3-6 hours has been employed. Use in MI, initial IV dose 5 mg every 2 minutes for 3 doses in the early treatment of myocardial infarction; after that, give 50 mg orally every 6 hours 15 minutes after last IV dose and continue for 48 hours; then administer a maintenance dose of 100 mg twice daily. When administered acutely for cardiac treatment, monitor ECG and blood pressure (Global, 2018).

Propranolol (Inderal) use in life-threatening arrhythmia dose is usually 1- 3 mg (maximum rate: 1 mg/min)-may dilute in 50 mL D5W. May repeat 1 mg dose every 5 minutes to a maximum of 5 mg total. Use subsequent doses no sooner than 4 hours. May start IV infusion: usual rate: 2 to 3 mg/hr. Titrate to HR/BP (Global, 2018).

Nursing Consideration

1. Check apical pulse. Some medications, such as metoprolol, should be held if the apical pulse is less than 60 beats/minute.
2. Educate the patient not to stop this medication suddenly. Stopping this medication can cause angina, arrhythmia, and MI.
3. Monitor renal and liver laboratory results.
4. Assess for adverse reactions.
5. Educate the patient on medication interactions.

Calcium channel blockers act on three calcium channels in the heart that control contractility and heart rate; the peripheral vascular system controls blood pressure and the brain's vascular system. The medication prevents calcium from entering these areas, resulting in increased oxygen to the heart and decreased contractility. The medications also slow the heart rate by suppressing the sinoatrial node and the atrioventricular node. Some of the medications in this category also dilate the peripheral vascular system and stop vasospasms in the brain. Because these medications cause vasodilation, headache is the most common complaint. Hypotension can also be common, along with dizziness, headache, dysrhythmias, edema, fatigue, drowsiness and flushing (Woo & Wynne, 2011).

Common agents include:

• Diltiazem (Cardizem, Tiazac)
• Felodipine (Plendil)
• Nifedipine (Procardia)
• Verapamil (Calan)
• Amlodipine (Norvasc)

Interactions can occur when administered with beta-blockers since both types of medication interfere with the AV node resulting in bradycardia, heart block and asystole. Calcium channel blockers should not be taken with grapefruit juice or cimetidine (Zantac), which may decrease cardiac output and hypotension. Furthermore, Dilantin and Tegretol may also interfere with the calcium channel blocker to work and may cause hypertension and angina. These medications may alter the effects of other medications such as theophylline, digoxin and cyclosporine (Woo & Wynne, 2011).

Clevidipine (Cleviprex) is indicated to reduce blood pressure when oral therapy is not feasible or not desirable. It is a milky white injectable emulsion; the initial dose is 1-2 mg/hour. To titrate, initially double the dose at short (90 second) intervals. As the blood pressure approaches the goal, increase the dose by less than doubling and lengthen the time between dose adjustments to every 5-10 minutes. An increase of approximately 1-2 mg/hour will generally produce an additional 2-4 mmHg decrease in systolic pressure. Most patients will achieve the desired therapeutic response at approximately 4-6 mg/hour. Most patients have received maximum doses of 16 mg/hour or less. There is limited experience with short-term dosing as high as 32 mg/hour. Because of lipid load restrictions, no more than 1000 mL or an average of 21 mg/hour of Cleviprex infusion is recommended per 24-hour period.

Cleviprex is in ready-to-use 50 mL or 100 mL vials. Invert the vial gently several times before use to ensure emulsion uniformity prior to administration. Administer using an infusion device allowing calibrated infusion rates. Cleviprex should not be administered in the same line as other medications. It should not be diluted, but it can be administered with the following (Global, 2018):

• Water for Injection, USP
• Sodium Chloride (0.9%) Injection, USP
• Dextrose (5%) Injection, USP
• Dextrose (5%) in Sodium Chloride (0.9%) Injection, USP
• Dextrose (5%) in Ringers Lactate Injection, USP
• Lactated Ringers Injection, USP
• 10% amino acid

Diltiazem (Cardizem) initial IV bolus is 0.25 mg/kg (or 20 mg) over 2 minutes; if inadequate response, may give second bolus 0.35 mg/kg (25 mg) after 15 min. For IV continuous infusion, the initial dose is 5-10 mg/hr; increase in 5 mg/hr increments up to 15 mg/hr maintained for up to 24 hr (Global, 2018).

Nicardipine (Cardene) initial IV dose is 5 mg/hour, increased by 2.5 mg/hour every 15 minutes to a maximum of 15 mg/hour; consider reduction to 3 mg/hour after the response is achieved. Monitor and titrate to the lowest dose necessary to maintain stable blood pressure (Global, 2018).

Verapamil (Isoptin) for arrhythmias, supraventricular IV bolus is 5-10 mg (0.075-0.15 mg/kg) over 2 min. May give an additional 10 mg after 30 minutes if there is no response (Global, 2018).

Nursing Considerations

1. Monitor apical pulse. Report an irregular beat or a rate below 60 beats/minute.
2. Assess for edema, crackles, dyspnea, weight gain, and jugular distention.
3. Assess for hypotension and bradycardia.
4. Educate the patient on orthostatic hypotension and how to rise slowly.
5. Review diet and exercise plan as sodium may need to be reduced.
6. Assess blood pressure. If systolic is below 90mm HG, report to the prescriber.

Diuretics cause increased fluid excretion through the kidneys, thus reducing the circulating blood volume and ultimately reducing blood pressure (Kaufman, 2014).

They inhibit the reabsorption of electrolytes such as sodium back into the circulatory system. There are three classes of diuretics; loop diuretics, thiazide diuretics, and potassium-sparing diuretics. Each type works at a different site within the kidney. Although these medications are widely used and cost-effective, care should be taken with special populations such as the elderly. Side effects can include electrolyte problems, especially hypokalemia, and sodium, potassium, hydrogen, and magnesium problems. Careful management through laboratory tests needs to be maintained (Kaufman, 2014).

Acetazolamide (Diamox) for glaucoma, the IV dose is 250-500 mg, may repeat in 2-4 hours to a maximum of 1 g/day. For edema, the IV dose is 250-375 mg once daily.

Bumetanide (Bumex) for edema associated with congestive heart failure, hepatic and renal disease, including the nephrotic syndrome IV bolus dose is 0.5-1 mg/dose over 1-2 minutes; may repeat in 2-3 hours for up to 2 doses if needed (maximum dose: 10 mg/day). Continuous infusion rate is 0.9 to 1 mg/hour.

Chlorothiazide (Diuril) IV dose is 500 mg to 1 g once or twice daily.

Ethacrynic Acid (Edecrin) IV dose is 50mg x 1 (0.5-1 mg/kg/dose). The maximum is 100 mg/dose. Usually, only one dose is necessary; occasionally, a second dose may be required. Use a new injection sit for the second dose to avoid possible thrombophlebitis, A single intravenous dose not exceeding 100 mg has been used in critical situations. Dilute in D5W or NS (1 mg/mL) and infuse over several minutes.

Furosemide (Lasix) for edema/CHF initial IV bolus is 20-40 mg over 1-2 min. May repeat in 1 to 2 hours or may be increased by 20 mg until desired response. This individually determined dose may be given once or twice daily. The initial IV bolus is 40 mg IV over 1-2 minutes for acute pulmonary edema. If not adequate, may increase the dose to 80 mg. Continuous infusion initial IV bolus dose of 0.1 mg/kg followed by continuous IV infusion doses of 0.1 mg/kg/hour doubled every 2h to a maximum of 0.4 mg/kg/hour if urine output is <1 ml/kg/hour. Other studies have used a rate of 4 mg/minute as a continuous IV infusion. For the elderly, the initial IV dose is 20 mg/day; increase slowly to the desired response. High doses (up to 1-3 g/day) for acute renal failure have been used to initiate the desired response. Avoid use in oliguric states. Replace parenteral therapy with oral therapy as soon as possible (Global, 2018).

Torsemide (Demadex) for CHF initial IV bolus is10-20 mg daily. Edema (liver disease) initial IV bolus is 5-10 mg. Edema (renal failure) initial IV bolus is 20 mg daily. May increase by doubling the dose. Maximum: 200 mg daily.

Nursing Considerations

1. Diuretics should be taken early in the day to prevent nocturia.
2. Monitor blood pressure, pulse, weight.
3. Monitor patients for the lupus-like syndrome. (sore throat, fever, muscle ache, joint aches, rash).
4. Assess for dizziness, orthostatic hypotension, general malaise, muscle or joint pain, and chest pain. Use diuretics with caution in the elderly because electrolyte disturbances and dehydration can occur rapidly.
5. The nursing assessment should include a daily weight, intake and output, and a check of skin turgor for dehydration.
6. Monitor for signs of metabolic alkalosis, including drowsiness and restlessness.
7. Monitor for signs of hypokalemia, including postural hypotension, malaise, fatigue, tachycardia, leg cramps and weakness., confusion, anuria.
8. Monitor electrolytes.
9. Thiazide can exacerbate diabetes and gout (JFC, 2013).
10. Avoid potassium supplements with a potassium-sparing diuretic.
11. Avoid Ace inhibitors with potassium-sparing diuretics.

Centrally acting alpha 2 antagonists are used to treat mild hypertension and are generally the second line of defense when other medications are ineffective (Woo & Wynne, 2011). However, methyldopa is the first-line medication for hypertension in pregnancy. These medications work by activating the alpha 2 receptors, inhibiting the cardio acceleration and vasoconstriction process in the brain. This reduction in sympathetic function, in turn, causes a decrease in peripheral norepinephrine and decreases peripheral resistance, renal vascular resistance, heart rate and blood pressure. These medications can cause sodium retention and are often given with a diuretic (Edmunds & Mayhew, 2013).

Common agents include:

• Clonidine (Catapres)
• Guanabenz (Wytensin)
• Guanfacine (Tenex, Intuniv)
• Methyldopa
• Clonidine/chlorthalidone (Clorpres) includes a thiazide diuretic.

Clonidine is absorbed via the GI tract and the skin. It is also lipid soluble and enters the brain from circulation. Guanabenz and guanfacine are also absorbed this way. However, methyldopa is only absorbed by about 50% in the GI tract. This medication enters the brain through amino acid transporters. Metabolism occurs in the liver and is excreted in urine (Woo & Wynne, 2011).

IV Methyldopate (Aldomet) add the desired dose to 100 mL of D5W. Alternatively, the desired dose may be given in D5W at a 100 mg/10 mL concentration. Give this intravenous infusion slowly for 30 to 60 minutes. Adult IV dosage is 250 mg to 500 mg at six-hour intervals. The maximum recommended intravenous dose is 1 gram every six hours.

Nursing Considerations

1. Review liver and renal function laboratory tests.
2. Assess for side effects including drowsiness, dry mouth, constipation, urinary tract infection, impotence, nightmare and insomnia with clonidine.
3. Assess for hypotension, chest pain, bradycardia.
4. GI symptoms are associated with guanabenz, including nausea, vomiting, anorexia, abdominal pain.
5. Assess for gynecomastia with guanabenz and clonidine.
6. Assess for pruritic rash.
7. Review medications for interactions such as beta-blockers.

Peripherally acting antiadrenergic inhibit sympathetic vasoconstriction by inhibiting the release of norepinephrine or depleting norepinephrine stores in adrenergic nerve endings (Woo & Wynne, 2011).

Common agents include:

• Prazosin (Minipress)
• Reserpine
• Terazosin (Hytrin)

Nursing Consideration

1. Assess blood pressure and pulse.
2. Be aware that the elderly are more sensitive to hypotensive effects.
3. Assess for dizziness, dry mouth, suddenly standing.
4. Monitor liver and renal functions in laboratory tests.
5. Review medication list for medication interactions. Diuretics may cause increased dizziness.
6. Review any herbs or over-the-counter medications used.

Peripheral vasodilators act with direct relaxation and dilation of the arteriolar smooth muscle. This action reduces peripheral vascular pressure and increases the pulse and cardiac output (Edmunds & Mayhew, 2013).

Common agents include:

• Diazoxide (Hyperstat IV)
• Hydralazine (Apresoline)
• Minoxidil (Loniten)

Fenoldopam Mesylate (corlopam) starting dose of 0.1 to 0.3 mcg/kg/minute. The dose is titrated at 15-minute intervals, depending on the BP response. It may be increased in increments of 0.05 to 0.1 mcg/kg/minute every 15 minutes until the target blood pressure is reached. Maximal infusion rate reported in clinical studies: 1.6 mcg/kg/minute. Onset/duration: 5-10 minutes/~ 1 hour (Global, 2018).

Hydralazine (Apresoline) Initial (Acute hypertension): 10 mg slow IV bolus (maximum dose being 20 mg) every 4 to 6 hours as needed. May increase to 40 mg/dose (generally speaking – do not exceed 20mg/dose). Change to oral therapy as soon as possible. The fall in blood pressure begins within 10 to 30 minutes and lasts 2 to 4 hours (Global, 2018).

Nesiritide (Natrecor) IV bolus of 2 mcg/kg (over 1 minute) followed by a continuous infusion of 0.01 mcg/kg/min. Withdraw the bolus dose from the infusion bag. Higher initial dosages are not recommended. At intervals of 3 hours, the dosage may be increased by 0.005 mcg/kg/minute (preceded by a bolus of 1 mcg/kg) up to a maximum of 0.03 mcg/kg/minute (Global, 2018).

Nicardipine (Cardene) The initial dose is 5 mg/hour and can be increased to a maximum of 15 mg/hour. Effects seen within 15 minutes. The initial 5 mg/hr dose can be increased by 2.5 mg/hour every 15 minutes to the previously listed maximum of 15 mg/hour. Consider reduction to 3 mg/hour after the response is achieved. Monitor and titrate to the lowest dose necessary to maintain stable blood pressure. Preparation: Dilute to 0.1 mg/ml (25 mg in D5W 250 ml) (Global, 2018).

Nipride (nitroprusside) is considered the most effective parenteral medication for most hypertensive emergencies, except for myocardial ischemia or renal impairment. The initial IV dose is 0.3-0.5 mcg/kg/minute. Increase in increments of 0.5 mcg/kg/minute, titrating to the desired hemodynamic effect or the appearance of headache or nausea. The usual dose is 3 mcg/kg/minute. Maximum dosage is 10 mcg/kg/minute (Global, 2018).

Epoprostenol (PGI2, prostacyclin) is used for long-term intravenous treatment of primary pulmonary hypertension and pulmonary hypertension associated with the scleroderma (Global, 2018).

The initial IV dose is 2 ng/kg/min IV. Titrate upward in increments of 2 ng/kg/min every 15 min or longer until dose-limiting pharmacological effects are elicited or until tolerance develops. Reconstitute only with supplied diluent; do not give with other parenteral medications. Infuse continuous chronic infusion via a central venous catheter with an ambulatory infusion pump. Epoprostenol may be administered peripherally until a central catheter is established. Avoid abrupt withdrawal. Anticipate the need for periodic dose adjustments (Global, 2018).

Antiarrhythmic medications are used to treat disturbances in normal heart rhythms. Careful monitoring must be observed as these medications can worsen conditions in the heart. There are 4 classes of antiarrhythmic. The desired endpoint of this therapy includes eliminating the dysrhythmias, controlling the heart rate and preventing the dysrhythmias from returning. Monitoring EKGs and the heart rate are integral parts of the therapy (Woo & Wynne, 2011).

Common adverse effects are faintness, syncope, hypotension, nausea, vomiting, diarrhea and abdominal pain. Symptoms of overdosage are hypokalemia, seizures and tachydysrhythmias (Nursing, 2016).

This class includes quinidine, disopyramide phosphate (Norpace), and procainamide hydrochloride (Pronestyl). These medications are quickly absorbed and metabolized. There are extended-release versions to prolong their effects. Quinidine does cross the blood-brain barrier. All are metabolized by the living and excreted thru the kidneys. Class 1A Antiarrhythmic works by blocking sodium channels, which change the impulses and cardiac cells. This effect occurs during different phases of the heart action potential. They also block parasympathetic stimulation of the Sinoatrial and AV nodes, increasing the AV node's conduction. These medications increase action potential duration and the refractory period and slow the conduction velocity. Class 1A medications treat premature ventricular contractions, ventricular tachycardia, atrial fibrillation, atrial flutter, and paroxysmal atrial tachycardia. Side effects particular to this class of medications are GI symptoms and a bitter taste (Zisaki et al., 2015).

IV Quinidine 80 mg/mL should be diluted to 50 mL (16 mg/mL) with D5W. An infusion of quinidine must be delivered slowly with a pump, no faster than 0.25 mg/kg/min (1 mL/kg/hour). During the first few minutes of the infusion, the patient should be monitored especially closely for possible hypersensitive or idiosyncratic reactions. Most arrhythmias that respond to intravenous quinidine will respond to a total dose of less than 5 mg/kg, but some patients may require as much as 10 mg/kg. If conversion to sinus rhythm has not been achieved after a 10 mg/kg infusion, the infusion should be discontinued (Global, 2018).

This class of medications includes mexiletine (Mexiletine) and lidocaine. These medications block sodium influx during the depolarization phase, especially in the Purkinje fiber system. This blocking results in a decreased refractory period and reduces the risk of arrhythmia. Class 1B medication is used only on ventricular arrhythmias. Side effects of this class of medications are drowsiness, lightheadedness, parenthesis, hypotension, and bradycardia. Particular to mexiletine are AV block, confusion, ataxia, double vision, nausea, vomiting, and tremors. Lidocaine can cause seizures and respiratory and cardiac arrest (Edmunds & Mayhew, 2013).

Lidocaine (Xylocaine) for ventricular arrhythmia 1-1.5 mg/kg IV bolus over 2-3 minutes; may repeat doses of 0.5-0.75 mg/kg in 5-10 minutes up to a total of 3 mg/kg; continuous infusion: 1-4 mg/minute (Global, 2018).

Prevention of ventricular fibrillation IV bolus: 0.5 mg/kg; repeat every 5-10 minutes to a total dose of 2 mg/kg. Refractory ventricular fibrillation: Repeat 1.5 mg/kg bolus may be given 3-5 minutes after initial dose (Global, 2018).

Class 1C antiarrhythmics are used to treat severe, resistant ventricular arrhythmias. Medications include flecainide acetate (Tambocor) and propafenone (Rythmol). These medications slow the conduction rate but do not have much of an effect on the action potential. Side effects include the development of new arrhythmias and aggravation of current arrhythmia, palpitations, shortness of breath, chest pain, heart failure and cardiac arrest.

Class II antiarrhythmics are beta-adrenergic blockers. These medications block beta-adrenergic receptors in the conduction system of the heart. This medication slows the firing of the SA Node and the AV Node, which decreases conductivity. These medications also reduce the strength of the contractions, so less force is needed with each beat, and therefore less oxygen is required. Class II medications are used for atrial flutter, atrial fibrillation, and paroxysmal atrial tachycardia. Medications include Propanolol, Timolol, Metoprolol, and Atenolol. Side effects include arrhythmia, bradycardia, heart failure, hypotension, GI reactions, bronchoconstriction and fatigue (Edmunds & Mayhew, 2013).

IV administration is discussed under the antihypertensive section.

Class III medications treat ventricular arrhythmias. These medications bind and block the potassium channels for phase 3 repolarization. This medication delays repolarization and increases potential action time in the effective refractory period. Medications in this class are amiodarone (Cordarone), sotalol (Betapace), bretylium tosylate (Bretylium) ibutilide (Corvert). Side effects include aggravation of current arrhythmia, hypotension, bradycardia, nausea, and anorexia. Amiodarone can cause vision issues. Ibutilide may sustain QT interval, and sotalol may cause AV block, bradycardia, bronchospasm and hypotension (Edmunds & Mayhew, 2013).

Amiodarone IV first 24 hours (Global, 2018):

1. Rapid infusion of 150 mg over 10 minutes (15 mg/min). Add 3 ml of Amiodarone (150 mg) to 100 ml D 5 W. Infuse 100 ml over 10 minutes.
2. Followed by Slow: 360 mg over the NEXT 6 hours (1 mg/min). Add 18 ml of Amiodarone IV (900 mg) to 500 ml D 5 W (conc = 1.8 mg/ml).
3. Maintenance infusion: 540 mg over the remaining 18 hours (0.5 mg/min).

After the first 24 hours, the maintenance infusion rate of 0.5 mg/min (720 mg/24 hours) should be continued utilizing a concentration of 1 to 6 mg/ml. In the event of breakthrough episodes of VF or hemodynamically unstable VT, give 150-mg/100 ml D5W over 10 minutes to minimize the potential for hypotension. The maintenance infusion rate may be increased to achieve effective arrhythmia suppression. The initial infusion rate should not exceed 30 mg/min (Global, 2018).

Amiodarone IV concentrations greater than 2 mg/ml should be administered via a central venous catheter.

Bretylium tosylate for immediate life-threatening ventricular arrhythmias, ventricular fibrillation, unstable ventricular tachycardia IV bolus 5 mg/kg the shock. Repeat in 5 minutes at 10 mg/kg (maximum total: 30 to 35 mg/kg). Side effects: Bradycardia, hypotension, N&V. Continuous infusion: 1 to 2 mg/min (Range: 0.5 to 4 mg/min). Add 1 gram to 250ml of D5W or normal saline (Global, 2018).

Ibutilide for acute termination of A-flutter/A-fib infuse 1mg IV over 10min. May repeat one time in 10 minutes if needed. It may be an alternative to cardioversion. Monitor ECG for at least 4hr. Effective in @30% of patients (Global, 2018).

For major adverse reactions: proarrhythmic events: VT, PVCs, BC, AV block, torsades de pointes, etc. IV piggyback 0 to 1 mg/50 ml D5W or NS over 10 minutes. If patient is < 60kg give 0.01 mg/kg over 10 minutes. May repeat once (Global, 2018).

Class IV medications are calcium channel blockers used to treat supraventricular arrhythmias. These medications block calcium ions in cardiac and smooth muscle cells, decreasing contractility. This medication decreases oxygen requirements and dilates coronary arteries and arterioles. Examples of Class IV medications are verapamil (Calan, Covera-HS, Verelan) and diltiazem (Cardizem) (Edmunds & Mayhew, 2013).

IV administration is discussed under the antihypertensive section.

Nursing Considerations and Patient Education

1. Monitor EEG, vital signs and apical pulse.
2. Monitor medication levels when indicated.
3. Monitor liver function and renal function laboratory results.
4. Assess for adverse reaction.
5. Educate patients on side effects.
6. Monitor weight as required.
7. Monitor fluid intake and output when indicated.

Cardiac glycosides are used to treat heart failure. The main ingredient is Digitalis purpurea. Digitalis (Lanoxin) cardiac works by increasing muscle contraction and slowing the heart rate. Because it is a heart stimulant, digoxin acts indirectly as a diuretic by promoting greater perfusion of blood through the kidneys. Furthermore, digoxin acts on the central nervous system to slow heart rate.

Adverse side effects of cardiac glycosides include dysrhythmias, anorexia, nausea, vomiting, bradycardia and headache (Woo & Wynne, 2011).

Digoxin getting once-daily IV maintenance doses can be treated on a regular unit. IV loading regimens (multiple doses) are restricted to patients on a monitor in the critical care area.

loading doses (Global, 2018):

• CHF: 8-12 mcg/ Normally, give 50% of the total digitalizing dose in the initial dose, then give 25% of the total dose in each of the two subsequent doses at 8 to 12 hr intervals. Obtain an EKG 6 hours after each dose to assess potential toxicity. Infuse IV Bolus over at least 5 min.
• Renal insufficiency dose 6 to 10 mcg/kg IBW.
• A-fib: 10 to 15 mcg/kg ideal body weight (IBW) kg in divided doses (every 4-8h) over 12 to 24 hours.

PSVT, for patients not on digoxin, give 0.25 to 0.5 mg IV. May follow with 0.125 to 0.25 mg IV every 2-6h until 0.75 to 1.5 mg is given over 24 hours. Digoxin is considered a 3rd line medication in stable patients who fail to respond to adenosine/verapamil/esmolol. Not the preferred medication for PSVT because it may take up to 60 minutes to be effective.

Digoxin maintenance dose depends on digoxin clearance, monitoring by maintaining blood samples at least 4 hours after IV dose.

Nursing Consideration and Patient Education

1. Prior to giving every digoxin dose, an apical heart rate must be taken. If the heart rate has slowed or a change in rhythm is detected, the dose should be withheld, and the physician should be notified. A heart rate of 60 or below is usually used to decide to hold the medication.

Antianginal agents reduce oxygen demand, increasing the oxygen to the heart or both. At therapeutic doses, they reduce systolic, diastolic and mean arterial blood pressures and improve coronary circulation. There are three classes of these medications: nitrates, Calcium channel blockers, and beta-adrenergic blockers (Edmunds & Mayhew, 2013).

Nitrates decrease peripheral vascular resistance or afterload and decrease preload. They also cause vasodilation and are typically used for acute angina as they have a rapid onset. Side effects are typically headaches, dizziness, orthostatic hypotension, flushing, and palpitations. Medications in this class are amyl nitrate, isosorbide dinitrate, isosorbide mononitrate, and nitroglycerin. These medications are given sublingually, chewable, or aerosol (Woo & Wynne, 2011).

IV administration is discussed under the antihypertensive section except for nitroglycerin.

IV nitroglycerin is caustic to normal plastic. Use glass bottles or specially made bags, Excel® or PAB®. The initial infusion rate is 5 mcg/min. May increase by 5 mcg/min every 3 to 5 minutes until response. If 20 mcg/minute is inadequate, increase by 10 to 20 mcg/min every 3 to 5 minutes. Maximum dose: 400 mcg/minute. Nitroglycerine is not for direct bolus. It must be diluted with D5W or NS.

Beta-adrenergic medications are used for the long-term prevention of angina. These include atenolol, metoprolol, nadolol, and propranolol. These medications reduce oxygen demand as it causes a decrease in heart rate and reduces the contraction force. Side effects include fainting, fluid retention, peripheral edema, GI disturbances, and constriction of bronchioles.

IV administration is discussed under the antihypertensive section.

Calcium channel blockers prevent angina that does not respond to the other antianginal medications. These medications include amlodipine, diltiazem, nifedipine and verapamil. These medications block the calcium ions from entering the cell membrane and smooth muscle cells, causing dilation of peripheral and coronary arteries. The heart decreases the contraction force of the heart and decreases afterload, increasing the oxygen supply. Side effects include orthostatic hypotension, dizziness, headache, weakness, flushing, peripheral edema, hypotension, bradycardia, and AV block (Nursing, 2016).

IV administration is discussed under the antihypertensive section.

Nursing Considerations and Patient Education

1. Assess for adverse reactions.
2. Assess apical pulse and vital signs.
3. Monitor serum medication levels.
4. Monitor liver function and renal function laboratory tests.
5. Monitor ECG as required.
6. Educate patient to change positions slowly, avoid alcohol and report side effects.

The Institute of Medicine recommends the following (Pham et al., 20102):

1. Routinely reconcile medication at admission, discharge or patient transfer
2. Avoid verbal orders except in emergencies
3. Assess all medications the patient is currently using
4. Keep medication records accurate and up-to-date
5. Assess for allergic reactions
6. Educate patients on all medications prescribed
7. Assess refill history and compliance
8. Review all side effects
9. Prescribe electronically when possible
10. Use read back with any orders
11. Avoid abbreviations
12. State patient age and weight if required for dosing
13. Nurses, pharmacists and prescribers should work as a team
14. Adhere to formularies and clinical guidelines
15. Use precautions as indicated with high-risk medications
16. Consult electronic references for the most up-to-date, evidence-based practices
17. Standardize patient transfers between units and facilities
18. Monitor patient for responses to medication changes
19. Minimize the use of samples

Charts of medication information are usually available on a unit or on the internet. Critical care areas usually have charts very specific to critical medications. Newer IV pumps have medication-specific information pre-programmed.

A meta-analysis of high-risk medications revealed that seven medications or classes caused approximately 47% of serious medication errors. These medications are methotrexate, warfarin, nonsteroidal anti-inflammatory medications (NSAIDs), digoxin, opioids, acetylic salicylic acid, and beta-blockers. It is estimated that over 70% of all medications identified were involved in fatal events.

The Institute for Safe Medication Practices reports the medications that are considered Look-Alike-Sound-Alike and high-risk medications. The list is extensive and should be reviewed periodically. The Institute recommends that the review include storage and dispensing procedures to help in decreasing sentinel events that involve medication errors (Institutional high alert meds). The most recent list can be found at www.ismp.org/tools/institutionalhighAlert.asp

The following is the list of high-risk IV medications (ISMP, 2018)

• adrenergic agonists, IV (e.g., Epinephrine, phenylephrine, norepinephrine)
• adrenergic antagonists, IV (e.g., propranolol, metoprolol, labetalol)
• anesthetic agents, general, inhaled and IV (e.g., propofol, ketamine)
• antiarrhythmics, IV (e.g., lidocaine, amiodarone)
• anticoagulants (e.g., warfarin, low molecular weight heparin, unfractionated heparin)
• chemotherapeutic agents
• dextrose, hypertonic, 20% or greater
• dialysis solutions
• moderate sedation agents, IV (e.g., dexmedetomidine, midazolam, Lorazepam)
• opioids
• neuromuscular blocking agents (e.g., succinylcholine, rocuronium, vecuronium)
• parenteral nutrition preparations
• sodium chloride for injection, hypertonic, greater than 0.9% concentration
• sterile water for injection, inhalation and irrigation (excluding pour bottles) in containers of 100 mL or more

Automation in pharmacy and nursing unit medication dispensing appears to decrease the number of medication errors. The evidence to support a computerized entry system as the ideal way to decrease medication error is marginal at best (Radley et al., 2013). Nevertheless, health care systems have moved to a more automated method of patient care, including computerized order entry, automated clinical decision support systems, and electronic health records (Wolcott et al., 2007). Barcoding systems for medication administration help identify the right patient, medication, dose, route, and time. This system has lowered the errors in the administration phase (Saedder et al., 2014). However, the transcription phase must be correct for the barcode to be effective.

Some physicians' orders are handwritten and then manually transcribed to a medication administration record. This method leaves many opportunities for errors. A computerized physician order entry, in which the physician must enter all orders by computer, eliminates handwriting and transcription errors but may not reduce administration errors (Wolcott et al., 2007). It also makes it possible to automatically check doses, medication interactions, allergies and significant patient data, like impaired renal function. Automation is very dependent upon each phase being correct. If one step is missed or is incorrect due to human inaccuracy, the risk of an adverse effect due to a medication error is significantly increased.

Automated systems can present several problems. There is a significant expense that smaller facilities may not be able to afford. Cost prohibitions or lack of space may limit the number of PCs because practitioners have long wait times for computer access. It also seems slow and inconvenient at times. In addition, less computer-savvy physicians may be resistant to fully implementing the system. Human error is also a factor. Education and communication are again the keys to decreasing medication errors.