While testing a hypolipidemic drug, serum lipid levels were tested both before and after its use. Which test is best suited for the statistical analysis of the result?

Paired T-test: is applied to paired data when each individual gives a pair of observation, such as when observations are made both before and after the play of a factor, e.g. Pulse rate before and after administration of a drug. In the question above serum lipid levels were tested both before and after administering a hypolipidemic drug. A paired t-test therefore is most suitable in this case. Ref: Fundamentals of Bio statistics, 2nd Edition By Rastogi V. B, Page 280