Morphineinteractions

Table 1 includes clinically significant drug interactions with morphine sulfate.

Table 1: Clinically Significant Drug Interactions with morphine sulfate Benzodiazepines and Other Central Nervous System (CNS) Depressants Clinical Impact: Due to additive pharmacologic effect, the concomitant use of benzodiazepines or other CNS depressants, including alcohol, can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.

Intervention: Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate. Limit dosages and durations to the minimum required. Follow patients closely for signs of respiratory depression and sedation. If concomitant use is warranted, consider prescribing naloxone for the emergency treatment of opioid overdose.

Examples: Benzodiazepines and other sedative hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, other opioids, alcohol.

Serotonergic Drugs Clinical Impact: The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.

Intervention: If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dose adjustment. Discontinue morphine sulfate if serotonin syndrome is suspected.

Examples: Selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, drugs that effect the serotonin neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), monoamine oxidase (MAO) inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue). Monoamine Oxidase Inhibitors (MAOIs) Clinical Impact: MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity (e.g., respiratory depression, coma).

Intervention: Do not use morphine sulfate in patients taking MAOIs or within 14 days of stopping such treatment.

Examples: phenelzine, tranylcypromine, linezolid Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics Clinical Impact: May reduce the analgesic effect of morphine sulfate and/or precipitate withdrawal symptoms.

Intervention: Avoid concomitant use.

Examples: butorphanol, nalbuphine, pentazocine, buprenorphine Muscle Relaxants Clinical Impact: Morphine may enhance the neuromuscular blocking action of skeletal muscle relaxants and produce an increased degree of respiratory depression.

Intervention: Evaluate patients for signs of respiratory depression that may be greater than otherwise expected and decrease the dosage of morphine sulfate and/or the muscle relaxant as necessary. Due to the risk of respiratory depression with concomitant use of skeletal muscle relaxants and opioids, consider prescribing naloxone for the emergency treatment of opioid overdose Examples: Cyclobenzaprine, metaxalone Cimetidine Clinical Impact: The concomitant use of cimetidine can potentiate morphine effects and increase risk of hypotension, respiratory depression, profound sedation, coma, and death.

Intervention: Evaluate patients for signs of respiratory depression that may be greater than otherwise expected and decrease the dosage of morphine sulfate and/or cimetidine as necessary.

Diuretics Clinical Impact: Opioids can reduce the efficacy of diuretics by inducing the release of antidiuretic hormone.

Intervention: Evaluate patients for signs of diminished diuresis and/or effects on blood pressure and increase the dosage of the diuretic as needed.

Anticholinergic Drugs Clinical Impact: The concomitant use of anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.

Intervention: Evaluate patients for signs of urinary retention or reduced gastric motility when morphine sulfate is used concomitantly with anticholinergic drugs. P-Glycoprotein (P-gp) Inhibitors Clinical Impact: The concomitant use of PGP-inhibitors can increase the exposure to morphine by about two-fold and can increase risk of hypotension, respiratory depression, profound sedation, coma, and death.

Intervention: Evaluate patients for signs of respiratory depression that may be greater than otherwise expected and decrease the dosage of morphine sulfate and/or the PGP-inhibitor as necessary.

Example: Quinidine Serotonergic Drugs: Concomitant use may result in serotonin syndrome. Discontinue morphine sulfate if serotonin syndrome is suspected. Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics: Avoid use with morphine sulfate because they may reduce analgesic effect of morphine sulfate or precipitate withdrawal symptoms.