Ambien (Zolpidem). Dosage, Side Effects, Interactions
Zolpidem is indicated for the short-term treatment of insomnia in adults and should only be used for insomnia of clinically significant severity.
Before prescribing a hypnotic, an underlying medical condition should be evaluated and treated. If there is no improvement in the sleep disorder after 7 to 14 days of treatment, the patient should be evaluated for possible primary mental or physical disorders.
Zolpidem is approved on the US market in the form of film-coated tablets in strengths of 5 mg and 10 mg. The film-coated tablet should be taken with sufficient liquid immediately before going to bed.
1. Use only when clearly indicated
2. Use of the smallest possible dose
3. Use over the shortest possible period
4. No abrupt discontinuation
5. Contraindications must be observed
How Ambien Zolpidem works
Chemically, the active substance zolpidem is a cyclopyrrolone derivative. It interacts with the α and γ subunits of the GABAA receptor. The consequence of this interaction with the GABAA receptor is the enhancement of the responses to GABA, which could be shown by electrophysiological methods. Zolpidem and zaleplon possess some selectivity for the α1 subunit of the GABAA receptor, but this has not been described for zopiclone .
Zolpidem has the following effects:
• Muscle relaxant
Compared to benzodiazepines, Z-substances apparently have less of an impact on sleep architecture, and the REM sleep phases in particular appear to be less affected.
Zolpidem is rapidly absorbed and has a rapid hypnotic effect. Bioavailability after oral administration is 70 percent. Zolpidem shows linear kinetics in the therapeutic dose range. The therapeutic plasma level is between 80 and 200 ng/ml. The peak plasma concentration is reached between 0.5 and 3 hours.
The volume of distribution is 0.54 l/kg in adults and is reduced to 0.34 l/kg in the elderly. Plasma protein binding is 92 percent. First-pass metabolism in the liver is approximately 35 percent. Repeat dosing did not result in a change in protein binding, suggesting that zolpidem is not displaced from protein binding by the metabolites.
The elimination half-life is short, averaging 2.4 hours with a duration of action of up to 6 hours. All metabolites are pharmacologically inactive and are excreted in the urine (56%) and faeces (37%). According to studies, zolpidem is not dialyzable.
Dosage of Ambien Zolpidem
The recommended daily dose for adults is 10 mg in the evening just before bedtime. However, the lowest effective dose should be used and the daily dose should not exceed 10 mg.
The duration of treatment should be as short as possible. It should generally range from a few days to 2 weeks and should not exceed 4 weeks, including the gradual withdrawal phase.
In pharmacokinetic studies, eight hours after taking zolpidem, women, unlike men, showed plasma concentrations at which impaired driving ability is to be expected. The US Food and Drug Administration (FDA) therefore recommended a daily dose of 5 mg for women.
Side effects of Ambien
The following side effects were common (≥ 1/100 to < 1/10) when using zolpidem:
- Upper and lower respiratory tract infections
- Hallucinations, agitation, nightmares, depression
- Drowsiness, headache, dizziness, increased insomnia, cognitive disorders such as anterograde amnesia
- Diarrhea, nausea, vomiting, abdominal pain
- Back pain
The following interactions should be considered when using zolpidem:
- Alcohol ► the sedative effect of zolpidem may be increased. The ability to drive and use machines is also affected by this combination.
- Centrally depressant drugs ( antipsychotics , hypnotics, anxiolytics/sedatives, antidepressants , narcotic analgesics, antiepileptics , narcotics and sedating antihistamines) ► Enhancement of the central depressant effect possible. There may be increased drowsiness and, the following day, psychomotor disturbances, including reduced ability to drive
- Antidepressants such as bupropion , desipramine, fluoxetine , sertraline , and venlafaxine ► isolated cases of visual hallucinations have been reported.
- Fluvoxamine ► Blood levels of zolpidem may be increased, so co-administration is not recommended.
- Narcotic analgesics ► Simultaneous use of narcotic analgesics can increase euphoria, which can accelerate the development of psychological dependence.
- Inhibitors and inducers of CYP450 ► Zolpidem is metabolised by some enzymes of the CYP450 enzyme system, in particular by the enzyme CYP3A4. Rifampicin accelerates zolpidem metabolism by enzyme induction (60% reduction in peak plasma concentrations and limitation of effect).
- CYP3A4 Inhibitors ► Increase in plasma concentrations of zolpidem and an increase in efficacy. However, co-administration of zolpidem with itraconazole (CYP3A4 inhibitor) does not result in any significant pharmacokinetic or pharmacodynamic changes. The clinical relevance of this is unknown.
- Ciprofloxacin ► Blood levels of zolpidem may be increased, so co-administration is not recommended.
Zolipdem must not be used in:
- Hypersensitivity to the active substance
- severe hepatic insufficiency
- sleep apnea syndrome
- Myasthenia gravis
- severe respiratory failure
- Children and young people under the age of 18
Although no teratogenic or embryotoxic effects have been demonstrated in animal studies, safety in human pregnancy has not been established. Therefore zolpidem should not be used, especially during the first trimester. If zolpidem is administered for compelling medical reasons during late pregnancy or during labour, effects on the neonate such as hypothermia, hypotension and mild respiratory depression are expected based on the pharmacological properties.
Zolpidem passes into breast milk in small amounts and should therefore not be taken during breast-feeding as there are no studies on the effects on the infant.
Zolpidem has major influence on the ability to drive and use machines.
Patients should be warned that there may be a possible risk of drowsiness, prolonged reaction time, dizziness, drowsiness, blurred/double vision and reduced alertness and impaired ability to drive the morning after ingestion. To minimize this risk, at least 8 hours should elapse between taking zolpidem and driving, using machines, or working at heights. Patients should also be warned not to drink alcohol or take any other psychoactive substances while using zolpidem.
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