Marinol

Dronabinol is a synthetic cannabinoid and a Schedule III controlled substance used primarily to treat chemotherapy-induced nausea and vomiting (CINV) and AIDS-related anorexia. It acts as an agonist at cannabinoid receptors to stimulate appetite and reduce emesis.

Dosing of Dronabinol must be carefully individualized, as the therapeutic window is narrow and patient response varies significantly.

Chemotherapy-Induced Nausea and Vomiting (CINV)

• Initial Dose: The standard starting dose is 5 mg/m², administered 1 to 3 hours prior to the administration of chemotherapy.
• Maintenance: The dose is then repeated every 2 to 4 hours after chemotherapy, for a total of 4 to 6 doses per day.
• Titration: If the 5 mg/m² dose is not effective and side effects are tolerated, the dose may be increased in increments of 2.5 mg/m² up to a maximum of 15 mg/m² per dose. However, caution is advised at higher doses due to the increased frequency of central nervous system (CNS) side effects.

AIDS-Related Anorexia

• Initial Dose: The typical starting dose is 2.5 mg orally twice daily, administered one hour before lunch and one hour before dinner.
• Titration: If the patient cannot tolerate 5 mg/day, the dose may be reduced to 2.5 mg once daily, administered in the evening or before bedtime to minimize daytime sedation. Conversely, if increased appetite is desired and side effects are minimal, the dose can be increased to 5 mg (2.5 mg before lunch and 2.5 mg before dinner) or up to 10 mg twice daily. Most patients respond well to 2.5 mg to 5 mg twice daily.

The safety and effectiveness of Dronabinol in pediatric patients have not been established. While it has been used off-label in some pediatric oncology cases, there are no standardized FDA-approved dosing guidelines for children. Healthcare providers must weigh the potential benefits against the significant risks of CNS effects in developing brains.

Renal Impairment

The pharmacokinetics of Dronabinol have not been extensively studied in patients with renal insufficiency. However, since renal excretion is a minor pathway for the parent drug, dosage adjustments may not be strictly required, though close monitoring for toxicity is essential.

Hepatic Impairment

Dronabinol is extensively metabolized by the liver. Patients with hepatic impairment may experience increased plasma concentrations and prolonged half-lives of the drug. Healthcare providers should initiate therapy at the lowest possible dose and monitor closely for adverse effects.

Elderly Patients

Elderly patients (65 years and older) are more sensitive to the psychoactive and cardiovascular effects of cannabinoids. It is recommended to start at the lower end of the dosing range (e.g., 2.5 mg once daily for anorexia) and titrate slowly while monitoring for confusion, dizziness, or falls.

• Consistency with Food: Dronabinol can be taken with or without food, but it should be taken consistently. Taking it with a high-fat meal can significantly increase absorption, which may lead to unexpected side effects.
• Oral Solution (Syndros): Use the provided calibrated oral dosing syringe to measure the dose accurately. Do not use a household teaspoon. The solution should be taken 1 hour before meals for appetite stimulation.
• Capsules: Swallow capsules whole. Do not crush, chew, or break them, as they contain sesame oil which is necessary for the drug's stability and absorption.
• Storage: Capsules should be stored in a cool environment (8°C to 15°C or 46°F to 59°F) or refrigerated. The oral solution should be refrigerated and discarded 90 days after opening.

If you miss a dose, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and resume your regular schedule. Do not double the dose to catch up, as this increases the risk of significant CNS depression or psychosis.

Signs of Dronabinol overdose include severe drowsiness, euphoria, heightened sensory awareness, altered time perception, reddened eyes, dry mouth, tachycardia (rapid heart rate), and orthostatic hypotension (dizziness upon standing). In severe cases, panic attacks, hallucinations, or seizures may occur.

In the event of a suspected overdose, contact your local poison control center or seek emergency medical attention immediately. Treatment is primarily supportive, focusing on maintaining airway patency and managing cardiovascular stability.

> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking the medication without medical guidance, as sudden discontinuation after prolonged use can lead to withdrawal symptoms.

Because Dronabinol is a psychoactive substance, side effects involving the central nervous system (CNS) are very common. These are often dose-related and may diminish as the patient develops tolerance over several days of therapy.

• Dizziness and Lightheadedness: Many patients feel a spinning sensation or instability, especially when moving from a sitting to a standing position.
• Euphoria: A feeling of being "high," exaggerated well-being, or inappropriate laughter is common. While some find this pleasant, others may find it distressing.
• Somnolence (Drowsiness): Significant sleepiness or lethargy is frequently reported, particularly during the first few days of treatment.
• Abdominal Pain: Some patients experience cramping or general discomfort in the stomach area.

Dronabinol is a potent psychoactive medication that requires careful medical supervision. It should only be used for the indications specifically approved by the FDA or as directed by a specialist. Patients should be aware that Dronabinol can significantly impair the mental and physical abilities required for driving or operating heavy machinery.

There are no FDA black box warnings for Dronabinol as of 2026. However, the medication carries significant warnings regarding its CNS effects and its potential for abuse.

• Psychiatric Risks: Dronabinol can cause or worsen psychiatric symptoms, including mania, depression, or schizophrenia. Patients with a personal or family history of these conditions should use Dronabinol with extreme caution. Symptoms like hallucinations or paranoia may require immediate discontinuation.

• Disulfiram and Metronidazole: The oral solution (Syndros) contains 50% alcohol. Taking it with disulfiram (Antabuse) or metronidazole (Flagyl) can cause a disulfiram-like reaction, characterized by severe nausea, vomiting, flushing, and tachycardia. This combination must be avoided within 14 days of using these medications.

• CNS Depressants: Medications such as benzodiazepines (e.g., diazepam, lorazepam), barbiturates, opioids, and sedating antihistamines can have additive effects with Dronabinol. This can lead to profound sedation, respiratory depression, and impaired motor skills.
• CYP3A4 and CYP2C9 Inhibitors: Drugs that inhibit these enzymes (e.g., ketoconazole, clarithromycin, ritonavir, amiodarone) can increase the plasma concentration of Dronabinol, significantly increasing the risk of toxicity and psychoactive side effects.

There are certain conditions and circumstances where Dronabinol must NEVER be used due to the risk of life-threatening complications:

• Hypersensitivity to Dronabinol: Any patient with a known history of severe allergic reaction to synthetic delta-9-THC or any component of the formulation.
• Sesame Oil Allergy (Capsules): The capsule formulation contains sesame oil. Patients with a sesame allergy are at risk of anaphylaxis.
• Alcohol Sensitivity (Solution): The oral solution contains 50% alcohol. It is contraindicated in patients who must avoid alcohol for medical or personal reasons.
• Recent Disulfiram or Metronidazole Use: Due to the alcohol content in the oral solution, it should not be used by patients who have taken disulfiram or metronidazole within the past 14 days.

Dronabinol is classified as Pregnancy Category C (under the older FDA system). There are no adequate and well-controlled studies in pregnant women. Animal studies have shown that THC can cross the placenta and may result in fetal growth restriction, skeletal abnormalities, and neurodevelopmental issues. Use during pregnancy should only be considered if the potential benefit justifies the potential risk to the fetus. It is generally recommended to avoid Dronabinol during pregnancy, especially in the first trimester.

Dronabinol and its metabolites are excreted in human milk. Cannabinoids can remain in breast milk for long periods. Because of the potential for serious adverse effects in the nursing infant (including developmental delays and sedation), the use of Dronabinol is generally not recommended for breastfeeding mothers. A decision should be made whether to discontinue nursing or discontinue the drug.

The safety and efficacy of Dronabinol in children have not been established. The pediatric brain is still developing, and the long-term impact of cannabinoid exposure on cognitive and emotional development is a significant concern. While it may be used in rare, refractory cases of pediatric CINV, this is always done under the strict guidance of a pediatric oncologist.

Dronabinol is an orally active cannabinoid which, like other cannabinoids, has complex effects on the central nervous system (CNS). It is a direct agonist at the CB1 and CB2 receptors. The antiemetic effect is believed to be caused by the activation of CB1 receptors in the dorsal vagal complex of the brainstem, which modulates the vomiting reflex. The appetite-stimulant effect is mediated through CB1 receptors in the hypothalamus and the mesolimbic reward system, enhancing the palatability of food and the drive to eat.

The effects of Dronabinol are dose-related. Low doses primarily produce appetite stimulation, while higher doses are required for antiemetic effects. The onset of action for appetite stimulation typically occurs within 30 to 60 minutes, with peak effects at 2 to 4 hours. The duration of action for CNS effects is generally 4 to 6 hours, although appetite stimulation can last for 24 hours or longer.

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