(US Adopted Name, rINN)
What Is Dronabinol?
Dronabinol is a synthetic form of delta-9-tetrahydrocannabinol (THC), the active component found in marijuana (Cannabis sativa). It is used for medicinal purposes and is often prescribed to manage specific conditions.
Dronabinol is primarily prescribed to manage chemotherapy-related nausea and vomiting in cancer patients who do not respond well to other antiemetic medications. It also stimulates appetite in people with HIV/AIDS who experience weight loss.
THC, the active ingredient in dronabinol, acts on the endocannabinoid system in the brain, which regulates various physiological processes, including appetite and nausea.
Dronabinol is available in capsule form and is typically taken orally. The capsules contain a specific amount of synthetic THC.
Common side effects of dronabinol include dizziness, drowsiness, euphoria, changes in mood, and increased appetite. It can also cause cognitive impairment, so individuals taking dronabinol should use caution when operating machinery or engaging in activities that require alertness.
Dronabinol is contraindicated in individuals with a known hypersensitivity to cannabinoids or sesame oil, which is used as a component in the formulation.
The safety of dronabinol during pregnancy and breastfeeding is not well established, and its use in these situations is generally avoided.
Dronabinol can interact with other medications, especially those that cause drowsiness or have potential CNS depressant effects. It’s crucial to inform healthcare providers about all medications being taken to avoid potential interactions.
Like other cannabinoids, dronabinol has the potential for abuse, and its use should be closely monitored, especially in individuals with a history of substance abuse.
Dronabinol is typically prescribed when other conventional treatments are ineffective, and healthcare providers carefully monitor its use. Individuals must communicate openly with their healthcare team about any side effects or concerns while using dronabinol.
Pharmacokinetics
After oral doses, dronabinol is slowly and erratically absorbed from the gastrointestinal tract. The bioavailability of an oral dose is about 10 to 20% due to extensive first-pass metabolism. Peak plasma concentrations of dronabinol and its 11-hydroxy metabolite are achieved about 2 to 4 hours after a dose by mouth. It is widely distributed and is extensively protein-bound, with a volume of distribution of about 10 liters/kg. Elimination is biphasic, with an initial half-life of about 4 hours and a terminal half-life of about 25 to 36 hours.
Dronabinol is extensively metabolized, mainly in the liver, by cytochrome P450 isoenzymes, the primary metabolite, 11 -hydroxydronabinol, is also active. The 11-hydroxy metabolite is converted to other, more polar and acidic compounds, which are excreted in feces via the bile and in the urine. About 50% of an oral dose is recovered in feces within 72 hours and 10 to 15% in urine. Many metabolites have relatively prolonged half-lives, and accumulation may occur with repeated dosage. Dronabinol is distributed into breast milk and crosses the placenta.
Uses and Administration
Dronabinol, the primary psychoactive constituent of cannabis, has antiemetic properties and controls nausea and vomiting associated with cancer chemotherapy in patients who have failed to respond adequately to conventional antiemetics.
The usual initial oral dose of dronabinol is 5 mg/m given 1 to 3 hours before the first dose of the antineoplastic drug, with subsequent doses being given every 2 to 4 hours after chemotherapy to a maximum of 4 to 6 doses daily. If necessary, the dose may be increased by increments of 2.5 mg/m to a maximum dose of 15 mg/m if adverse effects permit.
Dronabinol also has appetite-stimulant effects and is used in treating anorexia associated with weight loss in patients with AIDS. For this purpose, 2.5 mg may be taken twice daily, before lunch and supper, and reduced to a single 2.5 mg dose in the evening in patients who tolerate the drug poorly. If necessary, and if adverse effects permit, doses may also be increased up to 20 mg daily in divided doses.
Dronabinol is used with cannabidiol, another cannabinoid, in a buccal spray preparation as an adjunctive treatment for the symptomatic relief of neuropathic pain in multiple sclerosis in adults; this combination is also used as adjunctive analgesic treatment in adult patients with advanced cancer and is under investigation for some other conditions.
Alzheimer’s Disease
There is some suggestion that dronabinol may decrease agitation in patients with Alzheimer’s disease.
Anorexia
Dronabinol is used for the management of anorexia in patients with HIV-associated wasting. However, although dronabinol may stimulate appetite and prevent weight loss, it does not appear to produce significant weight gain and may produce less benefit than megestrol acetate. Benefits were also less than from megestrol in patients with anorexia associated with malignant disease.
Multiple Sclerosis
Anecdotal evidence has suggested that cannabinoids might improve symptoms in patients with multiple sclerosis, but a review considered evidence of effectiveness is lacking. In a large placebo-controlled study, treatment with dronabinol or oral cannabis extract had no benefit on objective assessment of spasticity; however, there were improvements in walking time and subjective improvements in both spasticity and pain. A subsequent small controlled study found dronabinol to have a modest but clinically relevant effect on central neuropathic pain in patients with multiple sclerosis. Dronabinol is used with cannabidiol, another cannabinoid, in a buccal spray preparation for the symptomatic relief of neuropathic pain in multiple sclerosis in adults.
Tourette’s Syndrome
Preliminary studies indicate that dronabinol may reduce tic severity in Tourette’s syndrome.
Adverse Effects and Precautions
As for Nabilone. The most frequent adverse effects of dronabinol include abdominal pain, nausea and vomiting, dizziness, euphoria, paranoid reactions, and drowsiness. Seizures and seizure-like activity have been reported; dronabinol should be used with caution in those with a history of seizure disorders, and therapy should be stopped if seizures occur.
Abuse
The abuse liability of dronabinol was rated as substantially lower than that of cannabis.
Breastfeeding
US-licensed product information states that dronabinol is concentrated in breast milk and recommends that it should not be used in breastfeeding mothers.
Drug Nomenclature
Pharmacopoeias. In US.
The United States Pharmacopeia 31, 2008 (Dronabinol). Store at a temperature between 8° and 15° in airtight glass containers in an inert atmosphere. Protect from light.
Preparations
The United States Pharmacopeia 31, 2008: Dronabinol Capsules.
Proprietary Preparations
Canada: Marinol
Israel: Ronabin
South Africa: Elevat
USA: Marinol
Multi-ingredient
Canada: Sativex
Jennifer is a clinical pharmacologist. She helps doctors of all medical specialties choose medications. Jennifer consults about drug dosage, interactions, and side effects.