Drug Interactions1
CNS-active drugs: An immediate-release formulation of zolpidem tartrate was evaluated in healthy volunteers in single-dose interaction studies for several CNS drugs. A study involving haloperidol and zolpidem tartrate revealed no effect of haloperidol on the pharmacokinetics or pharmacodynamics of zolpidem. Imipramine in combination with zolpidem tartrate produced no pharmacokinetic interaction other than a 20% decrease in peak levels of imipramine, but there was an additive effect of decreased alertness. Similarly, chlorpromazine in combination with zolpidem tartrate produced no pharmacokinetic interaction, but there was an additive effect of decreased alertness and psychomotor performance. The lack of a drug interaction following single-dose administration does not predict a lack following chronic administration.
An additive effect on psychomotor performance between alcohol and zolpidem tartrate was demonstrated.
A single-dose interaction study with zolpidem tartrate 10 mg and fluoxetine 20 mg at steady-state levels in male volunteers did not demonstrate any clinically significant pharmacokinetic or pharmacodynamic interactions. When multiple doses of zolpidem tartrate and fluoxetine at steady-state concentrations were evaluated in healthy females, the only significant change was a 17% increase in the zolpidem half-life. There was no evidence of an additive effect in psychomotor performance.
Following five consecutive nightly doses of zolpidem tartrate 10 mg in the presence of sertraline 50 mg (17 consecutive daily doses, at 7:00 am, in healthy female volunteers), zolpidem Cmax was significantly higher (43%) and Tmax was significantly decreased (53%). Pharmacokinetics of sertraline and N-desmethylsertraline were unaffected by zolpidem.
Since the systematic evaluations of Ambien CR in combination with other CNS active drugs have been limited, careful consideration should be given to the pharmacology of any CNS-active drug to be used with zolpidem. Any drug with CNS-depressant effects could potentially enhance the CNS-depressant effects of zolpidem.
Drugs that affect drug metabolism via cytochrome P450: A randomized, doubleblind, crossover interaction study in ten healthy volunteers between itraconazole (200 mg once daily for 4 days) and a single dose of an immediate-release formulation of zolpidem tartrate (10 mg) given five hours after the last dose of itraconazole resulted in a 34% increase in AUC0-8 of zolpidem. There were no significant pharmacodynamic effects of zolpidem on subjective drowsiness, postural sway, or psychomotor performance.
A randomized, placebo-controlled, crossover interaction study in eight healthy female volunteers between five consecutive daily doses of rifampin (600 mg) and a single dose of an immediate-release formulation of zolpidem tartrate (20 mg) given 17 hours after the last dose of rifampin showed significant reductions of the AUC (–73%), Cmax (–58%), and T1/2 (–36%) of zolpidem together with significant reductions in the pharmacodynamic effects of zolpidem.
Other drugs: A study involving cimetidine/zolpidem tartrate and ranitidine/ zolpidem tartrate combinations revealed no effect of either drug on the pharmacokinetics or pharmacodynamics of zolpidem. Zolpidem had no effect on digoxin kinetics and did not affect prothrombin time when given with warfarin in normal subjects. Zolpidem’s sedative/hypnotic effect was reversed by flumazenil; however, no significant alterations in zolpidem pharmacokinetics were found.
Drug/Laboratory test interactions: Zolpidem is not known to interfere with commonly employed clinical laboratory tests. In addition, clinical data indicate that zolpidem does not cross-react with benzodiazepines, opiates, barbiturates, cocaine, cannabinoids, or amphetamines in two standard urine drug screens.
Important safety information:
AMBIEN CR is indicated for the treatment of insomnia.
In elderly or debilitated patients, or patients with hepatic insufficiency, the recommended dose is 6.25 mg and patients should be closely monitored. Due to its rapid onset of action, patients should take AMBIEN CR right before going to bed and when ready for sleep.
Patients should not take AMBIEN CR unless they are prepared to get a full night's sleep (7 to 8 hours) to avoid residual effects.
Until they know how it will affect their physical or mental performance upon awakening, patients should not drive or operate hazardous machinery after taking AMBIEN CR or any other sleep medication. Complex behaviors such as somnambulism, including driving or eating while not fully awake, with amnesia for the event, have been reported in patients who have taken a sedative hypnotic. Discontinuation of AMBIEN CR should be strongly considered for patients reporting such complex behaviors. Rare cases of angioedema have been reported in patients after taking sedative hypnotics. Patients who develop angioedema should not be rechallenged. The most commonly observed adverse effects in controlled clinical trials were headache, somnolence, and dizziness. Because individuals with a history of addiction or substance abuse are at increased risk of habituation and dependence, they should be under careful surveillance when receiving AMBIEN CR or any o ther hypnotic. AMBIEN CR is a Schedule IV controlled substance. US clinical trial experience from zolpidem does not reveal any clear evidence for withdrawal syndrome.
Please refer to the full prescribing information.
References:
1 AMBIEN CR Prescribing Information.