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Volume 23: debated on Tuesday 4 May 1982

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asked the Secretary of State for Social Services (1) whether there has been liaison between his Department and the Netherlands national adverse reaction monitoring centre and the Netherlands Ministry of Health regarding the drug triazolam (Halcion); whether the Committee on Safety of Medicines has been given details of the adverse reaction reports which led to the banning of Halcion in the Netherlands; whether the Committee on Safety of Medicines has been told of the proportion of cases, for which there was an adverse reaction report, which involved dosage at levels recommended in Great Britain; and if so, what was the proportion;(2) how often and in what way the Committee on Safety of Medicines has given advice regarding dosage levels for the drug triazolam (Halcion);(3) if he will make a statement regarding the Committee on Safety of Medicines view of the balance of risk and advantage involved in the use of the drug triazolam (Halcion);(4) for how long the drug triazolam (Halcion) has been available on the British market; how many yellow card adverse reaction reports have been received by the Committee on Safety of Medicines during this period; whether there is any evidence of a higher notification rate for this drug than for other comparable hypnotics; and what type of adverse reactions possibly due to the drug have been reported;(5) whether the Committee on Safety of Medicines has consulted the American Food and Drug Association regarding the balance of risk and advantage involved in the use of the drug triazolam (Halcion); and whether the drug is available on the American market;(6) whether the Committee on Safety of Medicines has received any reports of adverse reactions following withdrawal of the drug triazolam (Halcion);(7) what response there was to the request by the Committee on Safety of Medicines in the February 1981 edition of "Current Problems" for doctors to inform it of suspected adverse reactions to triazolam (Halcion) and to other benzodiazepines;(8) whether the Committee on Safety of Medicines has made a specific study of the drug triazolam (Halcion); if so, what research studies were considered; what was the number of cases and controls in each study; and what was the conclusion of the studies.

[pursuant to his reply, 27 April 1982, Vol. 22, c. 239]: Triazolam (Halcion) was licensed in accordance with the advice of the Committee on Safety of Medicines and made available for prescription by doctors in the United Kingdom in early 1979. Detailed prescribing information, in particular guidance on dosage and warnings, is included in the data sheet which is made available to all medical practitioners by the company concerned.In the summer of 1979 the CSM was informed by the Netherlands Regulatory Authority of reports it had received of serious psychiatric adverse effects associated with treatment with triazolam. The committee reviewed the safety of the drug in the light of these reports and other relevant scientific evidence, including the confidential toxicological and clinical studies submitted with the original application, adverse reaction reports to the CSM itself, and the experience of use of the drug in other countries. It was noted that the experience in the Netherlands appeared to be unique, that the dose in general use there was at least double that recommended in the United Kingdom and often considerably higher, and that the extent and reporting of psychotic symptoms in the Netherlands might have been influenced by the very extensive publicity the matter had received. The CSM drew doctors' attention to the experience in the Netherlands and advised that the recommended maximum dose should not be exceeded; this advice was published in "Current Problems No. 5—February 1981—and doctors were invited to report suspected reactions to Halcion or other benzodiazepines.Since the drug was marketed, the CSM has received 152 reports of adverse reactions associated with triazolam, though these reports should not be interpreted as necessarily establishing a causal relationship. Suspected reactions reported include rashes, disorders of the central nervous system, psychiatric disorders and gastro-intestinal disorders. The few reports of psychiatric disorders similar to those reported in the Netherlands relate to cases where the recommended dose was known or suspected to have been exceeded. The committee has received no reports of reactions following the withdrawal of long-term treatment with triazolam; however, such effects have been reported in association with other drugs in this group. The nature of the reactions associated with triazolam is similar to those for other benzodiazepines and the reporting rate for triazolam is within the range found with drugs in this class. There has been no increase in reporting, either in relation to triazolam or other benzodiazepines, since "Current Problems No. 5" was published in February 1981. The committee has therefore no reason to alter its evaluation of the risk-benefit ratio for triazolam if it is used in accordance with the dosage, indications and precautions in the current data sheet.The Committee on Review of Medicines has reviewed all the benzodiazepines and has recommended the inclusion in the data sheets of additional statements on adverse reactions, including reports of abnormal psychological reactions. I understand that a revised data sheet on triazolam taking account of these recommendations will shortly be available to doctors.Triazolam is not at present marketed in the United States of America, and the CSM has had no reason to consult the Federal Food and Drug Administration about this drug.