NABILONE Drug Interactions: What You Need to Know

Drug Interactions Potential interactions between Cesamet 2 mg, and diazepam 5 mg; sodium secobarbital 100 mg; alcohol 45 mL (absolute laboratory alcohol); or codeine 65 mg, were evaluated in 15 subjects. Only a single combination was utilized at any one time. The subjects were evaluated according to physiologic (i.e., heart rate and blood pressure), psychometric, psychomotor, and subjective parameters. In this study, as expected, the depressant effects of the combinations were additive. Psychomotor function was particularly impaired with concurrent use of diazepam. Caution must thus be used when administering nabilone in combination with any CNS depressant. Nabilone is purportedly highly bound to plasma proteins, and therefore, might displace other protein-bound drugs. Therefore, practitioners should monitor patients for a change in dosage requirements when administering nabilone to patients receiving other highly protein-bound drugs. Published reports of drug-drug interactions involving cannabinoids are summarized in the following table. CONCOMITANT DRUG CLINICAL EFFECT(S) Amphetamines, cocaine, other sympathomimetic agents Additive hypertension, tachycardia, possibly cardiotoxicity Atropine, scopolamine, antihistamines, other anticholinergic agents Additive or super-additive tachycardia, drowsiness Amitriptyline, amoxapine, desipramine, other tricyclic antidepressants Additive tachycardia, hypertension, drowsiness Barbiturates, benzodiazepines, ethanol, lithium, opioids, buspirone, antihistamines, muscle relaxants, other CNS depressants Additive drowsiness and CNS depression Disulfiram A reversible hypomanic reaction was reported in a 28 y/o man who smoked marijuana; confirmed by dechallenge and rechallenge Fluoxetine A 21 y/o female with depression and bulimia receiving 20 mg/day fluoxetine X 4 wks became hypomanic after smoking marijuana; symptoms resolved after 4 days Antipyrine, barbiturates Decreased clearance of these agents, presumably via competitive inhibition of metabolism Theophylline Increased theophylline metabolism reported with smoking of marijuana; effect similar to that following smoking tobacco Opioids Cross-tolerance and mutual potentiation Naltrexone Oral THC effects were enhanced by opioid receptor blockade.

Alcohol

Increase in the positive subjective mood effects of smoked marijuana Animal Pharmacology and/or Toxicology Monkeys treated with Cesamet at doses as high as 2 mg/kg/day for a year experienced no significant adverse events. This result contrasts with the findings in a planned 1-year dog study that was prematurely terminated because of deaths associated with convulsions in dogs receiving as little as 0.5 mg/kg/day. The earliest deaths, however, occurred at 56 days in dogs receiving 2 mg/kg/day. The unusual vulnerability of the dog to Cesamet is not understood; it is hypothesized, however, that the explanation lies in the fact that the dog differs markedly from other species in its metabolism of Cesamet.

CONTRAINDICATIONS Cesamet is contraindicated in any patient who has a history of hypersensitivity to any cannabinoid.

WARNINGS

• The effects of Cesamet may persist for a variable and unpredictable period of time following its oral administration. Adverse psychiatric reactions can persist for 48 to 72 hours following cessation of treatment.
• Cesamet has the potential to affect the CNS, which might manifest itself in dizziness, drowsiness, euphoria “high”, ataxia, anxiety, disorientation, depression, hallucinations and psychosis.
• Cesamet can cause tachycardia and orthostatic hypotension.
• Because of individual variation in response and tolerance to the effects of Cesamet, patients should remain under supervision of a responsible adult especially during initial use of Cesamet and during dose adjustments.
• Patients receiving treatment with Cesamet should be specifically warned not to drive, operate machinery, or engage in any hazardous activity while receiving Cesamet.
• Cesamet should not be taken with alcohol, sedatives, hypnotics, or other psychoactive substances because these substances can potentiate the central nervous system effects of nabilone.