Allergic reactions can develop to tetrazepam and it is considered to be a potential allergen. Drug rash and drug-induced eosinophilia with systemic symptoms is a known complication of tetrazepam exposure. These hypersensitive allergic reactions can be of the delayed type. Drowsiness is a common side effect of tetrazepam. A reduction in muscle force can occur. Myasthenia gravis, a condition characterised by severe muscle weakness is another potential adverse effect from tetrazepam. Cardiovascular and respiratory adverse effects can occur with tetrazepam similar to other benzodiazepines. Prolonged use, as with all benzodiazepines, should be avoided, as tolerance occurs and there is a risk of benzodiazepine dependence and a benzodiazepine withdrawal syndrome after stopping or reducing dosage. Tetrazepam (is marketed under the following brand names, Clinoxan, Epsipam, Myolastan, Musaril, Relaxam and Spasmorelax) is a benzodiazepine derivative with anticonvulsant, anxiolytic, hypnotic and muscle relaxant properties. It is used mainly in Austria, France, Belgium, Germany and Spain to treat muscle spasm, anxiety disorders such as panic attacks, or more rarely to treat depression, premenstrual syndrome or agoraphobia. Tetrazepam has relatively little sedative effect at low doses while still producing useful muscle relaxation and anxiety relief. Tetrazepam is an unusual benzodiazepine in its molecular structure as it has cyclohexenyl group which has substituted the typical 5-phenyl moiety seen in other benzodiazepines. Tetrazepam, is rapidly absorbed after oral administration, within 45 mins and reaches peak plasma levels in less than 2 hours. It is classed as an intermediate acting benzodiazepine with an elimination half-life of approximately 15 hours. It is primarily metabolised to the inactive metabolites 3-hydroxy-tetrazepam and norhydroxytetrazepam. The pharmacological effects of tetrazepam are significantly less potent when compared against diazepam, in animal studies. Tetrazepam is a benzodiazepine site agonist and binds unselectively to type 1 and type 2 benzodiazepine site types as well as to peripheral benzodiazepine receptors. The muscle relaxant properties of tetrazepam are most likely due to a reduction of calcium influx. Small amounts of diazepam as well as the active metabolites of diazepam are produced from metabolism of tetrazepam. The metabolism of tetrazepam has led to false accusations of prisoners prescribed tetrazepam of taking illicit diazepam; this can lead to increased prison sentences for prisoners. Tetrazepam, like other benzodiazepines is a drug which is very frequently used in overdoses. These overdoses are often mixed overdoses, i.e. a mixture of other benzodiazepines or other drug classes with tetrazepam.