Ambien, also known by the generic name zolpidem, enhances inhibitory signaling in the brain by binding to a particular subclass of chemical receptors called benzodiazepine-GABA receptors. Physicians prescribe the drug for the treatment of insomnia, a condition where people find themselves unable to fall and stay asleep. Ambien comes in two forms: Ambien and Ambien CR, or controlled-release. Each form has specific advantages or disadvantages, but both medications should be taken with caution and under a doctor's supervision.

What is the Difference Between Ambien and Ambien CR?

According to the pharmaceutical company Sanofi-Aventis, Ambien CR is an extended- or modified-release version of the original Ambien formulation 12. Ambien CR tablets have two layers 1. The first dissolves rapidly to cause sedation, which facilitates the induction of sleep within 30 minutes. The second dissolves much more slowly over the evening to maintain slumber. Because of Ambien’s inconsistent effects on sleep maintenance, Ambien CR remains the only version of Ambien approved by the U.S. Food and Drug Administration for preventing spontaneous nighttime awakenings 2.

Advantages of Ambien CR vs. Ambien

Ambien CR exhibits steady concentrations in the blood for more than 3 hours after oral administration and has a longer duration of action than Ambien. Due to how fast the drug achieves and sustains certain levels in the body over time, doctors tend to prescribe Ambien CR at lower doses than Ambien. Unlike Ambien, Ambien CR can be prescribed for long-term as well as short-term use.

Advantages of Ambien vs. Ambien CR

Generic versions of Ambien--zolpidem tartrate--are available and cheaper than Ambien CR, which remains a proprietary formulation from Sanofi-Aventis 12. Interestingly, despite some of its strengths, Ambien CR might present unique side effects not presented by generic Ambien 2. For example, in the “Journal of Clinical Sleep Medicine,” Drs 34. Chiang and Krystal at Duke University Medical Center report that people using Ambien CR might have greater potential for exhibiting unconscious episodes of sleep-related eating than those taking the original formulation.

Shared Side Effects

Both Ambien and Ambien CR produce adverse effects typically observed with benzodiazepine medication, including headache, drowsiness, temporary amnesia, and dizziness or impaired balance 2. They can also cause psychological and physical dependence in some users. The likelihood of addiction grows the longer the drugs are taken.

General Safety Information: Drug Interactions

Researchers at Virginia Commonwealth University School of Pharmacy warn that alcohol and imipramine, a tricyclic antidepressant drug, can augment the clinical effects and toxicity of Ambien and Ambien CR 2. Ketoconazole, used in some dandruff shampoos and as an oral mediation to treat fungal infection, can also impair Ambien metabolism. Those seeking medical attention for insomnia should inform their doctors if they are using antifugal or antidepressant drugs.