§ Mrs. Renée Short
asked the Secretary of State for Social Services (1) in which countries the use of the drug clioquinol is banned; and for what reasons;
(2) what evidence has been submitted to the Committee on Safety of Medicines in the last five years about the adverse effects of the drug clioquinol; what action has been taken as a result; and if he is satisfied that its continued use is safe;
(3) for what uses the Committee on Safety of Medicines licenses the use of the drug clioquinol; and under what name it is sold in the United Kingdom.
§ Dr. Vaughan
[pursuant to his reply, 10 February 1981, c 317]: The information is as follows:
- Adults diarrhoea Mixture
- Entro Valodan tablets
- Entro-Vioform tablets
- Entox tablets
- lodochlorhydroxyquinoline tablets
- Oralcer pellets
- Tablets to Formula A49
- Unidiarea capsules
- Barquinol HC cream
- Betnovate C cream and Ointment
- Cor-tar-quin 0.5 per cent. cream
- Dioderm cream
- Haelan C cream and Ointment
- Locorten-Vioform products
- Nystaform products
- Propaderm C cream and Ointment
- Synalar-C cream and Ointment
- Vioform powder
- Vioform cream and Ointment
- Vioform Hydro-cortisone cream and Ointment
These products are used in the treatment of a number of conditions but the ointments are primarily indicated for infected dermatological conditions and the oral products for the treatment of gastro-intestinal illnesses caused by bacterial infection. All the oral products—except Oralcer which contains a very low dose of clioquinol—are available on prescription only.
The Committee on Safety of Medicines (CSM) has received 28 reports of adverse reactions to products containing clioquinol since 1975. In 1973 and July 1977 the committee reviewed the evidence relating to the occurrence of serious adverse effects associated with the use of the oral products containing clioquinol. It came to the conclusion in 1977 that the hazard of sub-acute myelo optic neuropathy (SMON) was insignificant at the approved dosages. However, in view of the unproven efficacy of clioquinol in the treatment of travellers' diarrhoea for which it was widely used, the committee was of the view that even a very small risk was unacceptable in the treatment of a minor condition. Acting on its advice, therefore, the licensing authority has taken action to 308W remove this indication for use from the product licences of the oral products containing clioquinol. In view of the other uses of clioquinol, the committee advised that it should remain available to doctors but on prescription only.
No confirmed case of SMON in the United Kingdom has been reported to the CSM and I am advised on the basis of the present evidence that, provided clioquinol is prescribed in accordance with the provision of the product licence, the benefits to patients far outweigh any possible risk.
Complete information is not available on the licensing position in other countries and this could be obtained only at disproportionate cost. I understand, however, that the drug has been compulsorily withdrawn from use completely in Japan, France, Norway and Sweden, because of the alleged association with SMON, and is no longer marketed in the United States. It is available on a restricted basis elsewhere in Western Europe and is widely available throughout the Third world.