nabilone

Action

Unclear. Drug has complex effects on CNS, including relaxation, drowsiness, and euphoria; antiemetic effect may result from interaction with cannabinoid receptor system in neural tissues.

Availability

Capsules: 1 mg

Indications and dosages

➣ Nausea and vomiting associated with cancer chemotherapy in patients who respond inadequately to conventional antiemetics

Adults: 1 to 2 mg P.O. twice daily; give initial dose 1 to 3 hours before chemotherapy. Maximum daily dose, 6 mg given in divided doses three times daily.

Contraindications

• Hypersensitivity to drug or other cannabinoids

Precautions

Use cautiously in:

• hepatic or renal impairment, hypertension, cardiac disease, QT interval prolongation, psychiatric disorders (current or previous)

• history of substance abuse

• concurrent use of sedatives, hypnotics, other psychoactive drugs, or CNS depressants

• concurrent alcohol use

• pregnant or breastfeeding patients

• elderly patients

• children (safety and efficacy not established).

Administration

• On day of chemotherapy, give 1 to 3 hours before chemotherapeutic drug is administered.

• To minimize adverse reactions, give recommended lower starting dosage and increase dosage as necessary.

• Know that drug may be given two or three times daily during entire course of each chemotherapy cycle and, if needed, for 48 hours after last dose of each chemotherapy cycle.

Adverse reactions

CNS: drowsiness, euphoria, dysphoria, inebriated feeling, mood swings, irritability, fatigue, malaise, ataxia, headache, poor concentration, disorientation, anxiety, depersonalization, depersonalization syndrome, speech disorder or disturbance, insomnia, abnormal dreams, vertigo, light-headedness, dizziness, orthostatic dizziness, twitching, depression, confusion, asthenia, sedation, hallucinations, paresthesia, memory disturbance, perception disturbance, seizures, dystonia, numbness, akathisia, tremor, incoordination, toxic psychosis, paranoia, apathy, thought disorder, panic disorder, withdrawal, nervousness, phobic neurosis, emotional disorder, hyperactivity, hypotonia, sinus headache

CV: orthostatic hypotension

EENT: visual disturbances, pharyngitis, nasal congestion, dry throat, dry nose, nosebleed, voice change, thick tongue sensation

GI: nausea, dry mouth

GU: increased or decreased urination, urinary retention, urinary frequency

Metabolic: thirst

Musculoskeletal: muscle pain, back pain, neck pain, joint pain

Respiratory: dyspnea, wheezing, cough

Skin: excessive sweating, pruritus, rash, photosensitivity

Other: taste changes, increased appetite, fever, hot flashes, chills, unspecified pain, bacterial infection, chest pain, allergic reaction

Interactions

Drug-drug. Amitriptyline, amoxapine, desipramine, other tricyclics: additive tachycardia, hypertension, drowsiness

Amphetamines, cocaine, other sympathomimetics: additive hypertension, tachycardia, possible cardiotoxicity

Anticholinergics, antihistamines, tri-cyclic antidepressants: increased tachycardia and hypertension

Antihistamines, atropine, scopolamine, other anticholinergics: additive or superadditive tachycardia, drowsiness

Antihistamines, barbiturates, benzodiazepines, buspirone, lithium, muscle relaxants, opioids, other CNS depressants: additive drowsiness and CNS depression

Antipyrine, barbiturates: decreased clearance of these drugs

Disulfiram, fluoxetine: reversible hypomanic reaction

Opioids: cross-tolerance and mutual potentiation

Naltrexone: enhanced nabilone effects

Theophylline: increased theophylline metabolism

Drug-behaviors. Alcohol use: increased positive mood effects, increased CNS depression

Sun exposure: increased risk of skin reactions

Patient monitoring

• Ensure that patient remains under supervision of responsible adult, especially during initial use and dosage adjustments.

• Monitor vital signs for orthostatic hypotension and tachycardia.

Check for adverse CNS reactions. Report significant depression, paranoid reaction, or emotional lability. Be aware that adverse psychiatric reactions can last for 48 to 72 hours after treatment ends.

• Monitor for excessive use, abuse, or misuse of drug.

• Monitor patient's nutritional and hydration status.

Patient teaching

• Instruct patient to take drug on day of chemotherapy 1 to 3 hours before chemotherapeutic drug is scheduled.

• Teach patient about significant CNS side effects (especially mood changes) and cardiovascular side effects. Stress importance of taking drug only as prescribed and needed.

• Inform patient that drug may cause additive CNS depression if used with alcohol or other CNS depressants (such as sleeping pills, tranquilizers, or anxiolytics).

Advise patient, family member, or caregiver to immediately report depression, suicidal thoughts, paranoid reactions, and other serious CNS reactions.

• Caution patient to avoid driving and other hazardous activities until drug effects are known.

• Instruct breastfeeding patient not to use drug while breastfeeding.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs and behaviors mentioned above.