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  • Define modified-release drug products.

  • Differentiate between conventional, immediate-release, extended-release, delayed-release, and targeted drug products.

  • Explain the advantages and disadvantages of extended-release drug products.

  • Describe the kinetics of extended-release drug products compared to immediate-release drug products.

  • Explain when an extended-release drug product should contain an immediate-release drug dose.

  • Explain why extended-release beads in capsule formulation may have a different bioavailability profile compared to an extended-release tablet formulation of the same drug.

  • Describe several approaches for the formulation of an oral extended-release drug product.

  • Explain why a transdermal drug product (patch) may be considered an extended-release drug product.

  • Describe the components of a transdermal drug delivery system.

  • Explain why an extended-release formulation of a drug may have a different efficacy profile compared to the same dose of drug given in as a conventional, immediate-release, oral dosage form in multiple doses.

  • List the studies that might be required for the development of an extended-release drug product.

  • List the several advantages of drug devices based on modified-release drug design.


Most conventional (also called immediate release [IR]) oral drug products, such as tablets, capsules, and solutions, are formulated to release the active pharmaceutical ingredient (API) immediately after oral administration. In the formulation of conventional drug products, no deliberate effort is made to modify the drug release rate. IR products generally provide relatively rapid drug absorption and onset of accompanying pharmacodynamic (PD) effects, but not always. In the case of conventional oral products containing prodrugs, the PD activity may be altered due to the time for conversion from prodrugs to the active drug by hepatic or intestinal metabolism or by chemical hydrolysis. Alternatively, in the case of conventional oral products containing poorly soluble (lipophilic drugs), drug absorption may be gradual due to slow dissolution in or selective absorption across the GI tract, also resulting in a delayed onset time.

To achieve a desired therapeutic objective and/or better patient compliance, the pattern of drug release from modified-release (MR) dosage forms is deliberately changed from that of a conventional (also called immediate-release, IR) dosage formulation. MR drug products are often a more effective therapeutic alternative to conventional or IR dosage forms. The objective of MR drug products for oral administration is to prolong the therapeutic effect of the active drug by controlling the rate of drug absorption from the gastrointestinal (GI) tract. MR formulations release a drug in a controlled manner during the absorption period, so they have advantages over IR formulas such as fewer pills to be taken and less peak−trough fluctuations of drug concentration in serum which may be associated with decreased adverse effects. Types of MR drug products include but are not limited to extended-release (ER), delayed-release (eg, enteric coated), targeted-release, and orally disintegrating tablets (ODT).

The term modified-release (MR) drug product is used to describe products that are formulated to alter the ...

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