**2.5 Single versus multiple dose study design**

If the dosage forms are to be evaluated only for bioequivalence purposes, single dose studies are sufficient. This is because the relative bioavailability of most tablets and capsules can be determined on a single dose basis and usually this is predictive of multiple dose levels. Dosage forms determined for a single dose administration for a therapeutic benefit such as analgesic for the relief of head ache needs only single dose studies [19]. However, certain dosage forms designed to achieve special release profiles of drugs may require multiple dose studies like time release products, enteric-coated preparations, and some intramuscular injections. Even the drugs that undergo the first pass metabolism do need a multiple dose study.
