Retard tablets or extended-release tablets are solid oral dosage forms that have been specifically formulated in such manner as to contain its active ingredient and release it over an extended period of time after administration. These kinds of dosage forms are also referred to as prolonged-action, repeat-action and sustained-release tablets.
Because of its extended-release formulation, the active ingredient contained in a tablet is released slowly over a given period of time, until the next dosage is administered. For example, an extended release vitamin C tablet will release its active ingredient, vitamin c, in consistent amounts for about 24 hours, until the next tablet is taken.
This method of drug release is advantageous for many drugs, such as those which require frequent administration (the drug can to be taken instead of, letís say every 4 hours, can be taken once a day, leading to higher patient compliance), drugs that cannot be taken in sudden, large amounts (for example, a drug that must be taken in slow, moderate and continuous amounts), and drugs that require continuous amounts.