These 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 The ones in this list have largely been superseded by newer, safer, drugs, including beta-blockers (see below).
These 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.
These drugs are sometimes also used to treat rheumatic conditions.
These drugs, which are used to relax and reduce the activity of the bladder and bowels, act by opposing the action of acetyl-choline (whereas drugs like mestinon promote it), and therefore carry a warning against their use in patients with MG. In fact, theoretically, they should not interfere with the action of acetyl-choline on muscle, and in practice there have been no reports of adverse effects in MG - perhaps because the warning has been so effective!
These drugs are used for the treatment of angina and other forms of heart disease, high blood pressure, migraine, and, occasionally, anxiety. They commonly produce a feeling of fatigue or muscle weakness, which tends to improve with continued treatment, and, rarely, have been reported to induce MG.
This is always listed among drugs which can precipitate MG, but actual reports of problems are rare.
A. Chlorpromazine and related drugs. These drugs are used in a wide variety of conditions. The original members of the group, chlorpromazepine and promazine, were reported to aggravate, or even to precipitate MG, but there are now a lot of newer analogues, and reports of trouble from these are rare. However it is probably still wise to use them cautiously.
These drugs are designed to cause muscle paralysis and are used almost exclusively by anaesthetists. For this reason, I consider it unnecessary to list them individually. There are two classes of muscle-relaxants: curare-like drugs, which must not be used in MG, and depolarising relaxants, which can sometimes be used. Both types must be distinguished from drugs such as the minor tranquillisers, which are often called "muscle-relaxants", although their effects are entirely non-specific.