What information should a rheumatologist give if their patient wants to try using medical marijuana to treat their rheumatic disease?
• Cannabinoid absorption is dependent on the route of administration. Inhaled/vaporized (10%–35% absorption) has rapid onset of effects (minutes) compared with oral (6% absorption, 2–6 hours to peak concentration). Transmucosal preparations have better absorption (15%) than oral ingestion. Most of an orally or transmucosally ingested cannabinoid is metabolized to an inactive form by its first-pass through the liver. This is why oral formulations are not very effective in rheumatic diseases.
• In spite of better absorption and rapid onset, smoking marijuana (cannabis) daily cannot be recommended due to multiple harmful compounds in marijuana smoke that can cause health issues including bronchitis, cardiovascular, and mental health issues. THC can have psychoactive effects, which impairs alertness and reaction time. Patients who smoke marijuana should not drive for up to 24 hours after consuming herbal cannabis.
• Medical cannabis should not be used in children, adolescents, pregnant women, or patients with previous abuse of psychoactive or pain medications.
• If the patient insists on trying medical cannabis, recommending vaporized CBD oil or topical formulations may be safest. However, the caveat remains that there is little standardization or regulation assuring product formulations and degree of bioavailability.
• Recently, the Food and Drug Administration approved Epidiolex, which is a liquid formulation of CBD used for childhood epilepsy syndromes. It is a schedule V medication that costs $32,000/year.
• Pain-management options other than medical cannabis are available with better evidence for safety and effectiveness. Most physicians agree that medical cannabis/cannabinoids should only be considered after all other measures for pain control have been tried.