Benzodiazepines are a group of drugs that slow down the central nervous system and decrease neuronal excitation.

Although there are different types, these drugs are mainly used as anxiolytics, hypnotics and muscle relaxants. Temazepam is an example of a benzodiazepine used to help people fall asleep and reduce nighttime awakening.

In this article we explain what temazepam is, what its main characteristics and clinical uses are, its mechanism of action, and the side effects, interactions and contraindications that we must take into account when using this medication.

Temazepam: characteristics and clinical uses

Temazepam is a drug from the benzodiazepine group used mainly in the treatment of insomnia and severe or disabling sleep disorders. This drug is also used in anxiety disorders, since in addition to having a hypnotic effect, it has an anxiolytic and sedative action. Its half-life is approximately 10 hours, so it is appropriate for treating maintenance insomnia.

This compound was patented in 1962, and marketed for medical use in 1969 under the name “Restoril”. In 1982 it was approved by the Food and Drug Administration (FDA), and several pharmaceutical companies now manufacture it in its generic form.

Studies in sleep laboratories have shown that temazepam significantly reduces the number of nighttime awakenings, although it has a distorting effect on normal sleep patterns. Temazepam is usually given orally and the effects begin 60 minutes later, lasting up to eight hours.

The prescription and consumption of benzodiazepines is widespread in the population , especially among the elderly. And although temazepam is a relatively safe and effective drug, its consumption quickly generates tolerance to its hypnotic and anxiolytic effects, which causes the dose to be increased. Prescription guidelines usually limit the use of this type of drug to two to four weeks, due to tolerance and dependency problems.

Because benzodiazepines can be abused, their use should be avoided by people in certain high-risk groups, such as people with a history of alcohol or other drug dependence, people with emotional problems, and patients with severe mental disorders.

Mechanism of action

Temazepam, like many other similar benzodiazepines, acts as a modulator of gamma-aminobutyric acid (GABA) and is capable of causing a variety of effects including: sedation, hypnosis, skeletal muscle relaxation, anticonvulsant activity and anxiolytic action.

GABA is considered the main inhibitory neurotransmitter in the human body. When this neurotransmitter binds to GABAA receptors found at neuronal synapses, chloride ions are conducted through the cell membranes of the neurons via an ion channel at the receptors. With sufficient chloride ions, the membrane potentials of the associated local neurons become hyperpolarized, making it more difficult or less likely for the action potentials to be triggered, resulting in reduced excitation of the neurons .

Although the main pharmacological activity of temazepam is to increase the effect of the neurotransmitter GABA, in animal studies (specifically in rats) it has also been shown that the drug triggers the release of vasopressin in the paraventricular nucleus of the hypothalamus and decreases the release of the adrenocorticotropic hormone under conditions of stress.

Interactions and contraindications

As with other benzodiazepines, temazepam produces central nervous system depressant effects when given in conjunction with other drugs that also produce this depressant effect, such as barbiturates, alcohol, opiates, tricyclic antidepressants, non-selective MAO inhibitors, phenothiazines and other antipsychotics, muscle relaxants, antihistamines and anaesthetics.

The administration of theophylline or aminophylline has been shown to reduce the sedative effects of temazepam and other benzodiazepines . Unlike many other benzodiazepines, pharmacokinetic interactions involving cytochrome P450 have not been observed with temazepam.

Also, temazepam does not show significant interaction with cytochrome CYP3A4 inhibitors, and oral contraceptives may decrease the effectiveness of this drug and speed up its elimination half-life. On the other hand, the use of temazepam should be avoided, as much as possible, in people with these conditions:

  • Ataxia (inability to coordinate muscle movements)

  • Severe hypoventilation

  • Severe liver deficiencies, such as hepatitis or cirrhosis

  • Severe kidney disorders (e.g., dialysis patients)

  • Closed-angle glaucoma

  • Sleep Apnea

  • Severe depression, especially if accompanied by suicidal tendencies

  • Acute intoxication with alcohol and other psychoactive substances

  • Myasthenia gravis

  • Hypersensitivity or allergy to benzodiazepines

Side effects

The consumption of temazepam is not exempt from possible side effects and adverse reactions . The most common and shared by the vast majority of benzodiazepines are related to central nervous system depression and include: drowsiness, sedation, drunkenness, dizziness, fatigue, ataxia, headache, lethargy, impaired memory and learning.

There may also be impaired motor functions and coordination, slurred speech, decreased physical performance, emotional numbness, decreased alertness, muscle weakness, blurred vision, and lack of concentration. Rarely, a state of euphoria has been reported following the consumption of temazepam. In addition, cases of retrograde amnesia and respiratory depression have been reported at high doses.

A 2009 meta-analysis found a 44% increase in the rate of occurrence of mild infections, such as pharyngitis and sinusitis , in people who had taken temazepam or other hypnotic medications compared to those who took a placebo.

On the other hand, cases of hyperhidrosis, hypotension, burning eyes, increased appetite, changes in libido, hallucinations, fainting, nystagmus, vomiting, itching, gastrointestinal disorders, nightmares, palpitations and paradoxical reactions such as restlessness, aggression, violence, overstimulation and agitation have been reported (in less than 0.5% of cases).

Bibliographic references:

  • Mitler, M. M., Mary A. Carskadon, R. L. Phillips, W. R. Sterling, V. P. Zarcone, R. Spiegel Jr, C. Guilleminault, & W. C. Dement. “Hypnotic efficacy of temazepam: a long-term sleep laboratory evaluation.” British journal of clinical pharmacology 8, no. Suppl 1 (1979): 63S.

  • Ruben, S. M., & Morrison, C. L. (1992). Temazepam misuse in a group of injecting drug users. British Journal of Addiction, 87(10), 1387-1392.

  • Schwarz, H. J. (1979). Pharmacokinetics and metabolism of temazepam in man and several animal species. British journal of clinical pharmacology, 8(Suppl 1), 23S.