Critical Reviews in Therapeutic Drug Carrier Systems · 2001 · 218 citations · 0 references
PharmacyPharmaceuticsPharmacologyDrug DeliveryMucosal Drug DeliveryOral Drug DeliveryControlled Release MechanismsControlled Release Oral Dosage FormsControlled-release SystemsDrug Delivery SystemsDrug Release From Dosage FormsDrug Release KineticsColonic Drug ReleaseControlled ReleaseDrug Release MechanismsOral Drug Delivery FormulationsOral Drug Delivery SystemsOral Pulsatile Release SystemsPulsatile Drug ReleaseSite-specific Release Systems
Pulsatile drug‑delivery systems, which release medication after a lag time and then rapidly, are increasingly studied for drugs with high first‑pass effects or chronopharmacological needs, and are classified as site‑specific systems triggered by intestinal pH or enzymes, or time‑controlled devices that release the drug after a defined period independent of the environment. This review surveys single‑ and multi‑unit oral pulsatile drug‑delivery systems, emphasizing time‑controlled release mechanisms. Time‑controlled pulsatile systems release the drug after a predetermined lag period, governed by the device rather than environmental factors.
Delivery systems with a pulsatile-release pattern are receiving increasing interest for the development of drugs for which conventional controlled drug-release systems with a continuous release are not ideal. These drugs often have a high first-pass effect or special chronopharmacological needs. A pulsatile-release profile is characterized by a time period of no release (lag time) followed by a rapid and complete drug release. Pulsatile drug-delivery systems can be classified into site-specific systems in which the drug is released at the desired site within the intestinal tract (e.g., the colon), or time-controlled devices in which the drug is released after a well-defined time period. Site-controlled release is usually controlled by environmental factors, like the pH or enzymes present in the intestinal tract, whereas the drug release from time-controlled systems is controlled primarily by the delivery system and, ideally, not by the environment. This review covers various single- and multiple-unit oral pulsatile drug-delivery systems with an emphasis on time-controlled drug-release systems.