Morphine can be given orally, rectally, intravenously, subcutaneously, or intramuscularly. It comes in tablet, suppository, and parenteral solution. Morphine also comes in a controlled release form, a sustained-release form, and an extended-release form. Morphine should not be used in those with a hypersensitivity to morphine, those with toxin-mediated diarrheal disease, and those with severe/acute asthma, paralytic ileus, or severe respiratory depression. The extended-release form should not be used in those with GI obstruction. The extended-release forms of morphine are not interchangeable. Changing from one drug to another should be done only by those with experience.
Fentanyl can be given as an injection, transdermal patch (Duragesic®), an oral transmucosal lozenge (Actiq®), a sublingual tablet (Abstral®), a sublingual spray (Subsys®), a buccal tablet (Fentora®), a buccal film (Onsolis®) and a nasal spray (Lazanda®). The transdermal patch is used in opioid-tolerant patients with moderate to severe pain and is changed every 72 hours. Fentanyl transmucosal and intranasal is indicated for cancer pain. The transdermal patch is for around-the-clock pain management in those with severe chronic pain.
Contraindications include hypersensitivity, toxin-mediated diarrheal disease, and paralytic ileus. It should not be used for short-term pain or post-operative pain and should not be used for those who have severe respiratory disease. The transmucosal and nasal forms of fentanyl are typically only used by specialists for opioid-tolerant cancer patients.
The patch form should not be exposed to external heat, as this may increase the absorption of the drug. Also, patients with a fever may notice an increase in the absorption of the drug. The patch should only be applied to intact skin, contains aluminum and must be removed before an MRI. Caution should be taken to remove a previous patch before applying a new patch to avoid overdose. Cutting patches can sometimes be done, depending on patch type, but may adversely affect their adhesiveness. In the case of reservoir patches, such as fentanyl, it can potentially lead to harmful immediate drug release.
Oxycodone is a schedule II-controlled substance available in controlled and Immediate release tablets. It also comes as an oral concentrate and oral solution. Oxycodone is often combined with NSAIDs. Oxycodone is contraindicated in those with paralytic ileus, significant respiratory depression, hypercarbia, acute or severe bronchial asthma, and GI obstruction. Caution should be used in those with biliary tract impairment, such as acute pancreatitis, as it may lead to constriction of the sphincter of Oddi. It may lead to an elevation of intracranial pressure (ICP) and should be used carefully for those with intracranial lesions, elevated ICP, or a head injury.
Hydrocodone is a Schedule II Controlled Substance. It is available as a combination pill with a non-narcotic analgesic and by itself in an extended-release form. The combination pill has a short-acting version of hydrocodone. Contraindications to hydrocodone include paralytic ileus, severe asthma, severe respiratory depression, and hypercarbia.
Tramadol is a schedule IV substance. It is indicated for those who do not need a rapid onset of pain relief. When prescribing tramadol to older adults, use the lower end of the dosage range and titrate slowly. Those over 75 years old utilize extreme caution with the extended-release form. Patients may experience withdrawal symptoms from tramadol, including nausea, diarrhea, anxiety, pain, sweating, tremor, and rigors. Decrease the dosage slowly to reduce the risk of withdrawal symptoms. Tramadol has been shown to increase the risk of seizures. This risk is increased in those who take serotonin reuptake inhibitors, tricyclic antidepressants, neuroleptics, other opioids, or drugs that lower the seizure threshold. The risk may also be increased in those with seizures or who are at risk for seizures, such as those with a CNS infection, cancer, history of head trauma, or while patients are going through drug or alcohol withdrawal.
Oxymorphone is a schedule II substance. It can be given intravenously, subcutaneously, intramuscularly, or orally. Hydromorphone can be given orally, rectally, subcutaneously, intramuscularly, or intravenously. The oral drug comes in standard and extended-release forms. Parental and oral doses are not equivalent. The parenteral dose is five times more potent than the oral dose. The long-acting form (Exalgo) is used for opioid-tolerant patients with chronic severe pain.
Methadone can be given intravenously, subcutaneously, intramuscularly, or orally. Methadone is at a high risk of overdose. It has a half-life of up to five days and may accumulate in the body. Methadone may also prolong the QT interval leading to cardiac arrhythmias, especially at doses higher than 120 mg daily. Methadone should be used for severe pain that has not been responsive to other agents and only by clinicians with specific training in using methadone. Methadone is also used in detoxification.
Tapentadol (Nucynta®, Nucynta® ER) is available in immediate-release and extended-release. It is indicated for diabetic peripheral neuropathy. Propoxyphene has been taken off the US market as it has been linked with fatal cardiac arrhythmias. Meperidine (Demerol) is not recommended as a first-line agent for chronic pain as it is associated with high central nervous system toxicity rates.