What is the problem with fixed-dose combinations?
Q: I am 54 years old and generally keep good health. I do take medicines for BP which are Stamlobeta and Ecosprin 75mg. Since the last couple of months, I have found that I have become more susceptible to infections viz. getting loose motions and recently swelling in eyes with throat infection. When my doctor prescribes medicines with tetracycline for this problem, I get loose motions after taking it for 3 days or more. This generally happens after I come back from my work tour of 2 days. Could you please advise any specific check up as there is nothing abnormal in my regular health check up package which was done recently?
A:Stamlo-beta is the brand name of a product that contains two drugs in fixed dose - atenolol 50mg and amlodipine 5mg. The problem with fixed-dose combinations (FDCs) is that one cannot change the dose of individual drugs. For example, a patient may need 100mg of atenolol and 2.5mg of amlodipine. Such a dosage adjustment cannot be done with an FDC. Hence in western countries, such FDCs are not legally permitted and are classified as Irrational Fixed-Dose Combinations. The other problem with FDCs is that side effects have an additive effect and it becomes very difficult to locate the exact cause of a side effect. For example amlodipine can cause altered bowel movements such as diarrhoea while atenolol can cause indigestion. It would be worth taking the two agents separately such as atenolol 50mg (e.g. Atecard or Aten or Tensimin) in the morning and amlodipine 5mg (e.g. Amlodac) in the evening not only for scientific reasons but also to see if your symptoms improve. Tetracycline needs to be avoided because the drug itself causes loose stools as a known side effect. Ecosprin 75 mg is fine. I do not think you need any tests.