Provigil Cannabis Interaction Profile: What You Need to Know Before Combining Modafinil and Weed

What is known about modafinil and cannabis together?

Modafinil is approved to improve wakefulness in adults with excessive sleepiness from narcolepsy, obstructive sleep apnea or shift work disorder, and it is a Schedule IV controlled substance available by prescription [2]. The label's drug interactions section covers CYP3A4/5 substrates (steroidal contraceptives, cyclosporine, midazolam, triazolam), CYP2C19 substrates (phenytoin, diazepam, propranolol, omeprazole, clomipramine), warfarin and MAO inhibitors [2]. Cannabis, THC and CBD are not named in that section [2].

The direct human evidence is a single crossover study, run to test modafinil as a possible treatment for cannabis use at a time when no medication had been proven effective for it [1].

What did the modafinil-plus-THC study find?

Twelve men and women who used cannabis occasionally completed four outpatient sessions in random order: 400 mg modafinil plus placebo, 15 mg oral THC plus placebo, 400 mg modafinil plus 15 mg THC, and double placebo, under double-blind conditions [1]. The study measured heart rate, blood pressure, performance on a rapid visual information processing task, the Hopkins Verbal Learning Test and subjective ratings [1]. Oral THC raised heart rate and increased ratings of feeling 'high', 'sedated' and euphoric; modafinil alone raised the vigor and tension subscales of the Profile of Mood States [1]. The authors wrote that the findings supported the safety of modafinil in combination with THC, and that the effects of modafinil with a range of THC doses still had to be determined [1].

Two limits matter. The modafinil dose was 400 mg, twice the 200 mg once-daily dose the label recommends for narcolepsy, sleep apnea or shift work disorder [2]. The cannabis was a single 15 mg oral THC dose, not smoked flower, a vape or a concentrate, and the design did not include CBD [1].

What does the label say about the heart?

The Provigil label's pooled placebo-controlled trials (934 patients on modafinil at 200, 300 or 400 mg and 567 on placebo) reported palpitation in 2% vs 1%, hypertension 3% vs 1% and chest pain 3% vs 1% [2]. More modafinil patients needed new or increased blood-pressure medicine: 2.4% vs 0.7% overall, and 3.4% vs 1.1% in the sleep apnea studies [2]. The label says to consider increased monitoring in patients with known cardiovascular disease, and that modafinil is not recommended in left ventricular hypertrophy or in mitral valve prolapse syndrome previously triggered by a CNS stimulant [2].

Cannabis has its own cardiovascular signal. French addictovigilance centres collected 35 reports of serious cardiovascular complications linked to cannabis use between 2006 and 2010, which was 1.8% of 1,979 cannabis-related reports: 20 acute coronary syndromes, 10 peripheral arterial complications and 3 cerebral events, with 9 deaths [3]. Of these patients 85.7% were men, and the average age was 34.3 years [3]. Spontaneous reports like these show that events occurred; they cannot give a rate per user.

Anxiety, insomnia and psychiatric symptoms

In the same pooled trials the label reports anxiety in 5% vs 1%, nervousness in 7% vs 3% and insomnia in 5% vs 1% [2]. Anxiety and nervousness each led to discontinuation in about 1% of patients, and insomnia in under 1% [2]. Postmarketing reports include mania, delusions, hallucinations, suicidal ideation and aggression, some requiring hospitalization, and many but not all of those patients had a prior psychiatric history [2]. The label says to use caution in patients with a history of psychosis, depression or mania and to consider discontinuing if psychiatric symptoms develop [2]. Hypersensitivity to modafinil, armodafinil or the inactive ingredients is the only listed contraindication [2]; a psychiatric history is not one.

Cannabis adds its own association. The EU-GEI case-control study compared 901 people with first-episode psychosis to 1,237 population controls across 11 sites: daily cannabis use carried an adjusted odds ratio of 3.2 (95% CI 2.2 to 4.1) for psychotic disorder compared with never use, and daily use of high-potency cannabis (THC 10% or more) an adjusted odds ratio of 4.8 (95% CI 2.5 to 6.3) [4]. Those are associations from a case-control design, not a measured risk for any one person who uses both drugs.

Liver enzymes and blood levels

Modafinil is a CYP3A4/5 inducer and a CYP2C19 inhibitor, about 90% of a dose is cleared by liver metabolism, and its effective half-life is roughly 15 hours after multiple doses [2]. The label's interaction section does not list cannabis, THC or CBD under either enzyme effect [2]. The 12-person study recorded heart rate, blood pressure, cognition and subjective effects, not plasma concentrations, so it does not show whether the two drugs change each other's blood levels [1].

Who is most exposed to a problem?

Two groups are named directly in the label. People with known cardiovascular disease are the ones singled out for increased monitoring, and people with a history of psychosis, depression or mania are the ones for whom caution is advised [2]. Modafinil also does not always restore normal wakefulness, so the label says patients should be reassessed for sleepiness and advised to avoid driving or other potentially dangerous activity when appropriate [2].

The label's abuse section states that modafinil is a Schedule IV controlled substance and says physicians should follow patients closely, particularly those with a history of drug or stimulant abuse, watching for dose increases or drug-seeking behavior [2]. It also says doses up to 400 mg are tolerated, with no consistent evidence of added benefit over 200 mg [2].