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Medication Safety Issues
Sound-alike/look-alike issues:
Dronabinol may be confused with droperidol
Pronunciation
(droe NAB i nol)
U.S. Brand Names
Index Terms
Generic Available
No
Canadian Brand Names
Pharmacologic Category
Use
Chemotherapy-associated nausea and vomiting refractory to other antiemetic(s); AIDS-related anorexia
Use: Unlabeled/Investigational
Cancer-related anorexia
Restrictions
C-III
Pregnancy Risk Factor
C
Lactation
Enters breast milk/contraindicated
Contraindications
Hypersensitivity to dronabinol, cannabinoids, sesame oil, or any component of the formulation, or marijuana; should be avoided in patients with a history of schizophrenia
Warnings/Precautions
Concerns related to adverse effects:
• CNS depression: May impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).
Disease-related concerns:
• Drug abuse: Use with caution in patients with a history of drug abuse or acute alcoholism; potential for drug dependency exists (drug is psychoactive substance in marijuana). Tolerance, psychological and physical dependence may occur with prolonged use.
• Hepatic impairment: Use with caution in patients with hepatic impairment; reduce dosage with severe impairment.
• Psychiatric disorders: Use with caution in patients with mania, depression, or schizophrenia; careful psychiatric monitoring is recommended.
• Seizure disorder: Use with caution in patients with a history of seizure disorder; may lower seizure threshold.
Concurrent drug therapy issues:
• CNS depressants: Effects may be potentiated when used with other psychoactive drugs, sedatives and/or ethanol.
Special populations:
• Elderly: Use with caution in the elderly; may cause postural hypotension.
• Pediatrics: Safety and efficacy have not been established in children.
Other warnings/precautions:
• Withdrawal: May cause withdrawal symptoms upon abrupt discontinuation.
Adverse Reactions
Frequency not always specified.
>1%:
Cardiovascular: Palpitations, tachycardia, vasodilation/facial flushing
Central nervous system: Euphoria (8% to 24%, dose related), abnormal thinking (3% to 10%), dizziness (3% to 10%), paranoia (3% to 10%), somnolence (3% to 10%), amnesia, anxiety, ataxia, confusion, depersonalization, hallucination
Gastrointestinal: Abdominal pain (3% to 10%), nausea (3% to 10%), vomiting (3% to 10%)
Neuromuscular & skeletal: Weakness
<1%, postmarketing, and/or case reports: Conjunctivitis, depression, diarrhea, fatigue, fecal incontinence, flushing, hypotension, myalgia, nightmares, seizure, speech difficulties, tinnitus, vision difficulties
Drug Interactions
CNS depressants: Sedative effects may be additive with CNS depressants; includes barbiturates, opioid analgesics, and other sedative agents; monitor for increased effect.
Phenothiazines (prochlorperazine): Combinations may result in additive or synergistic effects (as antiemetics), but sedation must be monitored.
Ethanol/Nutrition/Herb Interactions
Ethanol: Avoid ethanol (may increase CNS depression).
Food: Administration with high-lipid meals may increase absorption.
Herb/Nutraceutical: St John's wort may decrease dronabinol levels.
Storage
Store under refrigeration (or in a cool environment) between 8°C and 15°C (46°F and 59°F). Protect from freezing.
Mechanism of Action
Unknown, may inhibit endorphins in the brain's emetic center, suppress prostaglandin synthesis, and/or inhibit medullary activity through an unspecified cortical action. Some pharmacologic effects appear to involve sympathimometic activity; tachyphylaxis to some effect (eg, tachycardia) may occur, but appetite-stimulating effects do not appear to wane over time. Antiemetic activity may be due to effect on cannabinoid receptors (CB1) within the central nervous system.
Pharmacodynamics/Kinetics
Onset of action: Within 1 hour
Peak effect: 2-4 hours
Duration: 24 hours (appetite stimulation)
Absorption: Oral: 90% to 95%; 10% to 20% of dose gets into systemic circulation
Distribution: Vd: 10 L/kg; dronabinol is highly lipophilic and distributes to adipose tissue
Protein binding: 97% to 99%
Metabolism: Hepatic to at least 50 metabolites, some of which are active; 11-hydroxy-delta-9-tetrahydrocannabinol (11-OH-THC) is the major metabolite; extensive first-pass effect
Half-life elimination: Dronabinol: 25-36 hours (terminal); Dronabinol metabolites: 44-59 hours
Time to peak, serum: 0.5-4 hours
Excretion: Feces (50% as unconjugated metabolites, 5% as unchanged drug); urine (10% to 15% as acid metabolites and conjugates)
Dosage
Refer to individual protocols. Oral:
Antiemetic: Children and Adults: 5 mg/m2 1-3 hours before chemotherapy, then 5 mg/m2/dose every 2-4 hours after chemotherapy for a total of 4-6 doses/day; increase doses in increments of 2.5 mg/m2 to a maximum of 15 mg/m2/dose.
Appetite stimulant: Adults: Initial: 2.5 mg twice daily (before lunch and dinner); titrate up to a maximum of 20 mg/day.
Monitoring Parameters
CNS effects, heart rate, blood pressure, behavioral profile
Reference Range
Antinauseant effects: 5-10 ng/mL
Test Interactions
Decreased FSH, LH, growth hormone, and testosterone
Dietary Considerations
Capsules contain sesame oil.
Patient Education
Do not take any new medication during therapy unless approved by prescriber (especially barbiturates and benzodiazepines). Take exactly as directed; do not increase dose or take more often than prescribed. Avoid alcohol. May cause psychotic reaction, impaired coordination or judgment, faintness, dizziness, or drowsiness (do not drive or engage in activities that require alertness and coordination until response to drug is known); or clumsiness, unsteadiness, or muscular weakness (change position slowly and use caution when climbing stairs). Report excessive or persistent CNS changes (euphoria, anxiety, depression, memory lapse, bizarre thought patterns, excitability, inability to control thoughts or behavior, fainting); respiratory difficulties; rapid heartbeat; or other adverse reactions. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to become pregnant. Do not breast-feed.
Geriatric Considerations
Elderly patients may be more sensitive to the CNS effects and postural hypotensive effects of dronabinol. Titrate the dose slowly and monitor for adverse effects.
Dental Health: Effects on Dental Treatment
Key adverse event(s) related to dental treatment: Xerostomia (normal salivary flow resumes upon discontinuation) and orthostatic hypotension
Dental Health: Vasoconstrictor/Local Anesthetic Precautions
No information available to require special precautions
Mental Health: Effects on Mental Status
Drowsiness, anxiety, confusion, and mood changes are common; may cause depression or hallucinations
Mental Health: Effects on Psychiatric Treatment
Concurrent use with barbiturates and benzodiazepines produce additive sedation
Nursing: Physical Assessment/Monitoring
Use caution in the presence of heart disease, hepatic disease, or seizure disorders. Assess potential for interactions with other pharmacological agents or herbal products patient may be taking. Assess effectiveness of therapy according to purpose for use. Monitor closely for adverse psychotic reactions; this drug is the psychoactive substance in marijuana. Teach patient appropriate use, possible side effects/appropriate interventions, and adverse symptoms to report.
Oncology: Emetic Potential
Very low (<10%)
Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, gelatin:
Marinol®: 2.5 mg, 5 mg, 10 mg [contains sesame oil]
Pricing: U.S. (www.drugstore.com)
Capsules (Marinol)
2.5 mg (30): $200.01
10 mg (30): $723.16
References
Anderson PO and Muire GG, “Delta-9-Tetrahydrocannabinol as an Antiemetic,” Am J Hosp Pharm, 1981, 38:639-46.
Cat LK and Coleman RL, “Treatment for HIV Wasting Syndrome,” Ann Pharmacother, 1994, 28(5):595-7.
Plasse TF, Gorter RW, Krasnow SH, et al, "Recent Clinical Experience with Dronabinol," Pharmacol Biochem Behav, 1991, 40(3):695-700.
Struwe M, Kaempfer SH, Geiger CJ, et al, “Effect of Dronabinol on Nutritional Status in HIV Infection,” Ann Pharmacother, 1993, 27(7-8):827-31.
Tramer MR, Carroll D, Campbell FA, et al, “Cannabinoids for Control of Chemotherapy Induced Nausea and Vomiting: Quantitative Systematic Review,” BMJ, 2001, 323(7303):16-21.
Voth EA and Schwartz RH, “Medicinal Applications of Delta-9-Tetrahydrocannabinol and Marijuana,” Ann Intern Med, 1979, 126(10):791-8.
International Brand Names
Lexi-Comp.com
Last full review/revision April 2008
Content last modified April 2008
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