Recent Advances in Oral Pulsatile Drug Delivery

Abstract

Pulsatile drug delivery aims to release drugs on a programmed pattern i.e.: at appropriate time and/or at appropriate site of action. Currently, it is gaining increasing attention as it offers a more sophisticated approach to the traditional sustained drug delivery i.e: a constant amount of drug released per unit time or constant blood levels. Technically, pulsatile drug delivery systems administered via the oral route could be divided into two distinct types, the time controlled delivery systems and the site-specific delivery systems. The simplest pulsatile formulation is a two layer press coated tablet consisted of polymers with different dissolution rates. Homogenicity of the coated barrier is mandatory in order to assure the predictability of the lag time. The disadvantage of such formulation is that the rupture time cannot be always adequately manipulated as it is strongly correlated with the physicochemical properties of the polymer. Gastric retentive systems, systems where the drug is released following a programmed lag phase, chronopharmaceutical drug delivery systems matching human circadian rhythms, multiunit or multilayer systems with various combinations of immediate and sustained-release preparation, are all classified under pulsatile drug delivery systems. On the other hand, site-controlled release is usually controlled by factors such as the pH of the target site, the enzymes present in the intestinal tract and the transit time/pressure of various parts of the intestine. In this review, recent patents on pulsatile drug delivery of oral dosage forms are summarized and discussed.

Circadian Timing in Cancer Treatments

“…However, optimal chronotherapeutic delivery at night when the patient is sleeping requires adaptive drug delivery technologies. Novel oral pulsatile drug delivery systems release active drug principles after a predetermined lag time following ingestion and have proven their clinical relevance for chronotherapeutics (123,124). Such systems could critically improve the safety and efficacy of orally dosed anticancer medications through circadian optimization of drug exposure.…”

QBD-Based Development and Evaluation of Enteric Coated Mucoadhesive Microcapsules of Amoxicillin Trihydrate as a Novel Chronotherapeutic Approach for Treatment of Bacterial Infections

“…Carr's Index and Hausner's ratio were determined by tapping method. The microcapsules were tapped using USP tapped density tester (Electrolab-1020, Mumbai, India) for 1000 taps in a cylinder and the change in volume was measured [2,16]. The angle of repose, Carr's index and Hausner's ratio were calculated by formulae (5-7): …………….…”

“…It is primarily active against gram positive bacteria by inhibiting their cell wall synthesis [1,2]. It exhibits lower stability in gastric acid due to cleavage of C≡N bond of the β-lactam ring which leads to loss of potency with reduced oral bioavailability [3].…”

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“…This is possible by filling an additional magnetic component into capsules or tablets. The speed of travel through the stomach and intestines can then be slowed down at specific positions by an external magnet, thus changing the timing and/or extent of drug absorption into stomach or intestines [23][24][25]26 .…”