Some drugs are available in different formulations. When changing to a different formulation it may be necessary to change the dosage regimen. Simply using the same amount of drug can result in therapeutic problems.


Examples of different formulations: oral suspension, rapid release, delayed release



(1) bioavailability and absorption

(2) rate of drug release


If a new formulation has better absorption/bioavailability than a current one, then the same dose of the new formulation will result in high drug levels, possibly causing toxicity.


If a new formulation has a lowe absorption then the same dose could cause a subtherapeutic dose.


If a drug has a slower release than another, then the drug concentration will probably be more constant.


If a drug has a faster release, then there may be wider swings in drug concentration. Use of a smaller dose more often may be necessary.


If one formulation has similar bioavailability and a rate of drug release to another, then the same dose can be used. Else problems may occur.


To read more or access our algorithms and calculators, please log in or register.