Medazepam

Medazepam is a drug which is a benzodiazepine derivative. It possesses anxiolytic, anticonvulsant, sedative and skeletal muscle relaxant properties.

It is known by the following brand names: Nobrium®, Rudotel®, Raporan®,Ansilan® .^[1] Medazepam is a long acting benzodiazepine drug. The half life of medazepam is 36 - 200 hours.^[2]

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Pharmacology

Medazepam and other benzodiazepines may influence neurosteroid metabolism and altering levels of progesterone which in turn may adversely influence the functions of the brain and reproductive system. The pharmacological actions of benzodiazepines at the GABAa receptor are similar to those of neurosteroids. Neuroactive steroids are positive allosteric modulators of the GABAa receptor, enhancing GABA function. Many benzodiazepines (diazepam, medazepam, estazolam, flunitrazepam and nitrazepam) potently inhibit the enzymes involved in the metabolism of neurosteroids. Long-term administration of benzodiazepines may influence the concentrations of endogenous neurosteroids, and thereby would modulate the emotional state. Factors which effects benzodiazepines ability to alter neurosteroid levels depend on the molecular make up of the individual benzodiazepine molecule. Presence of a substituent at N1 position of the diazepine ring and/or the chloro or nitro group at position 7 of the benzene ring contribute to potent inhibition of the isoenzymes, and in turn a bromo group at position 7 (for bromazepam) and additional substituents (3-hydroxy group for oxazepam and tetrahydroxazole ring for cloxazolam and oxazolam) decrease the inhibitory potency of benzodiazepines on neurosteroids.^[3] Benzodiazepine drugs including medazepam increase the inhibitory processes in the cerebral cortex.^[4]

Overdose

Medazepam is a drug which is very frequently involved in drug intoxication, including overdose.^[5]

The Committee on the Review of Medicines

The Committee on the Review of Medicines (UK) carried out a review into benzodiazepines due to significant concerns of tolerance, drug dependence and benzodiazepine withdrawal problems and other adverse effects. The committee found that benzodiazepines do not have any antidepressant or analgesic properties and are therefore unsuitable treatments for conditions such as depression, tension headaches and dysmenorrhoea. Benzodiazepines are also not beneficial in the treatment of psychosis due to a lack of efficacy. The committee also recommended against benzodiazepines being used in the treatment of anxiety or insomnia in children. The committee was in agreement with the Institute of Medicine (USA) and the conclusions of a study carried out by the White House Office of Drug Policy and the National Institute on Drug Abuse (USA) that there was little evidence that long term use of benzodiazepine hypnotics were benefitial in the treatment of insomnia due to the development of tolerance. Benzodiazepines tended to lose their sleep promoting properties within 3 - 14 days of continuous use and in the treatment of anxiety the committee found that there was little convincing evidence that benzodiazepines retained efficacy in the treatment of anxiety after 4 months continuous use due to the development of tolerance. The committee found that the regular use of benzodiazepines caused the development of dependence characterised by tolerance to the therapeutic effects of benzodiazepines and the development of the benzodiazepine withdrawal syndrome including symptoms such as anxiety, apprehension, tremor, insomnia, nausea, and vomiting upon cessation of benzodiazepine use. Withdrawal symptoms tended to develop within 24 hours on the cessation of a short acting benzodiazepine and within 3 - 10 days after the cessation of a more short acting benzodiazepine. Withdrawal effects could occur after treatment lasting only 2 weeks at therapeutic dose levels however withdrawal effects tended to occur with habitual use beyond 2 weeks and were more likely the higher the dose. The withdrawal symptoms may appear to be similar to the original condition. The committee recommended that all benzodiazepine treatment be withdrawn gradually and recommended that benzodiazepine treatment be used only in carefully selected patients and that therapy be limited to short term use only. It was noted in the review that alcohol can potentiate the central nervous system depressant effects of benzodiazepines and should be avoided. The central nervous system depressant effects of benzodiazepines may make driving or operating machinery dangerous and the elderly are more prone to these adverse effects. In the neonate high single doses or repeated low doses have been reported to produce hypotonia, poor sucking, and hypothermia in the neonate and irregularities in the fetal heart. Benzodiazepines should be avoided in lactation. Withdrawal from benzodiazepines should be gradual as abrupt withdrawal from high doses of benzodiazepines may cause confusion, toxic psychosis, convulsions, or a condition resembling delirium tremens. Abrupt withdrawal from lower doses may cause depression, nervousness, rebound insomnia, irritability, sweating, and diarrhoea.^[6]

References

1. ^ http://www.drug-encyclopedia.eu/DW_EN/benzodiazepines.shtml
2. ^ Professor heather Ashton (April 2007). BENZODIAZEPINE EQUIVALENCY TABLE. Retrieved on Sept 23, 2007.
3. ^ Usami N; Yamamoto T, Shintani S, Ishikura S, Higaki Y, Katagiri Y, Hara A. (Apr 2002). "Substrate specificity of human 3(20)alpha-hydroxysteroid dehydrogenase for neurosteroids and its inhibition by benzodiazepines." (pdf). Biol Pharm Bull. 25 (4): 441-5. PMID 11995921.
4. ^ Zakusov VV; Ostrovskaya RU, Kozhechkin SN, Markovich VV, Molodavkin GM, Voronina TA. (Oct 1977). "Further evidence for GABA-ergic mechanisms in the action of benzodiazepines." 229 (2): 313-26. PMID 23084.
5. ^ Zevzikovas A; Kiliuviene G, Ivanauskas L, Dirse V. (2002). "[Analysis of benzodiazepine derivative mixture by gas-liquid chromatography]". Medicina (Kaunas). 38 (3): 316-20. PMID 12474705.
6. ^ Committee on the Review of Medicines (29). "Systematic review of the benzodiazepines. Guidelines for data sheets on diazepam, chlordiazepoxide, medazepam, clorazepate, lorazepam, oxazepam, temazepam, triazolam, nitrazepam, and flurazepam. Committee on the Review of Medicines." (pdf). Br Med J. 280 (6218): 910-2. PMID 7388368.