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Drugs which may aggravate MG Dr Stanley Freedman The important word in the title of this article is "may". Just as myasthenics differ widely in the sites and severity of their weakness, so they differ in their susceptibility to the effects of drugs, as, indeed, do non-myasthenics. There are, therefore, no absolute prohibitions, apart possibly from some of the drugs used in anaesthesia, and no need to panic if you are taking, or have taken, one of the drugs listed below without any ill-effects. If your MG is well-controlled, these drugs are very unlikely to have any ill-effects, and it is important not to deny yourself their benefits. Decisions about whether or not to take a drug must be made in consultation with your doctor. It should also be emphasised that while these drugs may make the symptoms of MG worse, none of them affects the basic disease process, apart from penicillamine. From the doctor's viewpoint, problems arise because information on the drugs, in reference books as well as in the packaging, is often inaccurate. Some drugs, temazepam being a good example, are labelled as being absolutely contra-indicated in MG, when in fact they do not affect it at all, while on the other hand, some drugs which commonly aggravate MG do not carry a warning. Further problems arise for doctor and patient, because of the profusion of available drugs. For example, no fewer than 15 different "beta-blockers" are licensed for use in the UK, and any one of these may be marketed by several companies under different brand names. In this article, I have listed drugs according to their class, and provided both "official" name, in bold, and trade names, where these are different, in italic. Popular mixtures which contain the offending drug are listed (in brackets). I have attempted a brief outline of how they may affect MG. As well as tablets and injections, I have listed preparations used locally in the eye, as significant amounts of drug can be absorbed into the bloodstream when given by this route. Also, beware of laxatives, which can impair the absorption, and therefore the effectiveness, of all your drugs, but particularly of pyridostigmine (mestinon). 1. ANTI-ARRHYTHMICSThese are used to treat and prevent irregular heart beat. The ones in this list have largely been superseded by newer, safer, drugs, including beta-blockers (see below).
· Quinidine Kinidin Durules 2. ANTIBIOTICSThese are used to prevent and treat bacterial infections. One group (A), which contains six members, affects transmission between nerve and muscle, and therefore can make MG worse. They are chiefly given by injection, and you are therefore most likely to come across them in hospital. You are more likely to encounter those in groups B, which are usually given as tablets, often for chest infections, but which are much less likely to upset your MG, and C, which are commonly used for bladder and kidney infections. Group D is now used very rarely.
3. ANTI-MALARIALSThese drugs are sometimes also used to treat rheumatic conditions.
4. ANTI-RHEUMATIC DRUGS
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