Not every drug can be safely or effectively compounded.
For those that can, properties, including pharmacokinetics and pharmacodynamics, can be altered.1 In some instances (eg, when using transdermal methimazole), efficacy can be evaluated with clinical monitoring (in this case, a thyroid panel). It is important to evaluate each drug and discuss the options with a compounder before choosing a compounded product.
A big misconception about compounding is that it is synonymous with use of a generic drug.
A generic drug, like its brand name counterpart, is a manufactured drug. Manufactured drugs are made on a large-scale, regulated by the FDA, and intended to be distributed to many patients. Compounding, however, is done on a much smaller scale, is not directly regulated by the FDA, and is intended for individual patients. For example, tramadol 50-mg tablets are commercially available from many manufacturers, either as the brand name or as the generic tramadol HCl identified by a National Drug Code. However, the tablet strength is too high for many smaller patients, so a tramadol 10-mg/mL suspension offers a safer option. The suspension formulation, however, is not available from a large-scale manufacturer and therefore would have to be formulated by a compounding pharmacy and customized on an individual patient basis.