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Ambien vs. Ambien CR

author image Fabian Fernandez, Ph.D.
Based in Miami, Fabian Fernandez has been writing science- and health-related articles since 2004. His work has appeared in several prestigious academic magazines including "Nature" and ”Proceedings of the National Academy of Sciences." Fernandez received a National Science Foundation (NSF) Graduate Fellowship in 2003, and a Research Service Award from the NIH in 2007. He holds a Ph.D. in neurosciences from Stanford University.
Ambien vs. Ambien CR
Ambien and Ambien CR are used to treat insomnia.

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.

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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. Ambien CR tablets have two layers. 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.

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. Interestingly, despite some of its strengths, Ambien CR might present unique side effects not presented by generic Ambien. For example, in the “Journal of Clinical Sleep Medicine,” Drs. 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. 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. 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.

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