Dronabinol
(Delta-9-tetrahydro-cannabinol)
Dronabinol (Marinol)
Delta-9-tetrahydro-cannabinol (Marinol)
Dronabinol
(droh- NAB-ih-nohl)
Pregnancy Category: C Marinol (C-III) (Rx)

Classification: Antinauseant

Action/Kinetics: As the active component in marijuana, significant psychoactive effects may occur. (See Side Effects.) In therapeutic doses, the drug also causes conjunctival injection and an increased HR. Antiemetic effect may be due to inhibition of the vomiting center in the medulla. Peak plasma levels: 2-3 hr. Significant first-pass effect. The 11-hydroxytetrahydrocannabinol metabolite is active. t 1/2, biphasic: 4 hr and 25-36 hr. t 1/2, 11-hydroxy-THC: 15-18 hr. Metabolized in the liver and mainly excreted in the feces. Cumulative toxicity using clinical doses may occur. Highly bound to plasma proteins and may thus displace other protein-bound drugs.

Uses: Nausea and vomiting associated with cancer chemotherapy, especially in clients who have not responded to other antiemetic treatment. To stimulate appetite and prevent weight loss in AIDS clients.

Contraindications: Nausea and vomiting from any cause other than cancer chemotherapy. Lactation. Hypersensitivity to sesame oil.

Special Concerns: Monitor pediatric and geriatric clients carefully due to an increased risk of psychoactive effects. Use with caution in clients with hypertension, occasional hypotension, syncope, tachycardia; those with a history of substance abuse, including alcohol abuse or dependence; clients with mania, depression, or schizophrenia (the drug may exacerbate these illnesses); clients receiving sedatives, hypnotics, or other psychoactive drugs (due to the potential for additive or synergistic CNS effects).

Side Effects: CNS: Side effects are due mainly to the psychoactive effects of the drug and, in addition to those listed in the preceding, include dizziness, muddled thinking, coordination difficulties, irritability, weakness, headache, ataxia, cannabinoid ``high,'' paresthesia, hallucinations, visual distortions, depersonalization, confusion, nightmares, disorientation, and confusion. CV: Palpitations, tachycardia, vasodilation, facial flush, hypotension. GI: Abdominal pain, N&V;, diarrhea, dry mouth, fecal incontinence, anorexia. Respiratory: Cough, rhinitis, sinusitis. Other: Asthenia, conjunctivitis, myalgias, tinnitus, speech difficulty, vision difficulties, chills, headache, malaise, sweating, elevated hepatic enzymes.
Symptoms of Abstinence Syndrome: An abstinence syndrome has been reported following discontinuation of doses greater than 210 mg/day for 12-16 days. Symptoms include irritability, insomnia, and restlessness within 12 hr; within 24 hr, symptoms include ``hot flashes,'' sweating, rhinorrhea, loose stools, hiccoughs, and anorexia. Disturbed sleep may occur for several weeks.

Overdose Management: Symptoms: Extension of the pharmacologic effects. Symptoms of mild overdose include: drowsiness, euphoria, heightened sensory awareness, altered time perception, reddened conjunctiva, dry mouth, and tachycardia. Symptoms of moderate toxicity include impaired memory, depersonalization, mood alteration, urinary retention, and reduced bowel motility. Severe intoxication includes decreased motor coordination, lethargy, slurred speech, and postural hypotension. Seizures may occur in clients with existing seizure disorders. Hallucinations, psychotic episodes, respiratory depression and coma have been reported. Treatment: Clients with depressive, hallucinatory, or psychotic reactions should be placed in a quiet environment and provided supportive treatment, including reassurance. Diazepam (5-10 mg PO) may be used for extreme agitation. Hypotension usually responds to IV fluids and Trendelenburg position. In unconscious clients with a secure airway, administer activated charcoal (30-100 g in adults and 1-2 g/kg in children); this may be followed by a saline cathartic.

Drug Interactions: Amphetamine / Additive hypertension, tachycardia, possibly cardiotoxicity Anticholinergics / Additive/super additive tachycardia; drowsiness CNS depressants / Additive depression Cocaine / See Amphetamine Antidepressants, tricyclic / Additive tachycardia, hypertension, drowsiness Ethanol / During subchronic dronabinol use, lower and delayed peak alcohol blood levels Sympathomimetics / See Amphetamine Theophylline / Possible increased drug metabolism

How Supplied: Capsule: 2.5 mg, 5 mg, 10 mg

Dosage
?Capsules Antiemetic.
Adults and children, initial: 5 mg/m ² 1-3 hr before chemotherapy; then, 5 mg/m ² q 2-4 hr for a total of four to six doses/day. If ineffective, this dose may be increased by 2.5 mg/m ² to a maximum of 15 mg/m ²/dose. However, the incidence of serious psychoactive side effects increases dramatically at these higher dose levels.
Appetite stimulation.
Initial: 2.5 mg b.i.d. before lunch and dinner. If unable to tolerate 5 mg/day, reduce the dose to 2.5 mg/day as a single evening or bedtime dose. If side effects are absent or minimal and an increased effect is desired, the dose may be increased to 2.5 mg before lunch and 5 mg before dinner (or 5 mg at lunch and 5 mg after dinner). The dose may be increased to 20 mg/day in divided doses. The incidence of side effects increases at higher doses.