Palatal mucosa as a route for systemic drug delivery: A review.

Rapid developments in the field of molecular biology and gene technology resulted in generation of many macromolecular drugs including peptides, proteins, polysaccharides and nucleic acids in great number possessing superior pharmacological efficacy with site specificity and devoid of untoward and toxic effects. However, the main impediment for the oral delivery of these drugs as potential therapeutic agents is their extensive pre-systemic metabolism, instability in acidic environment resulting into inadequate and erratic oral absorption. Parenteral route of administration is the only established route that overcomes all these drawbacks associated with these orally less/inefficient drugs. But, these formulations are costly, have least patient compliance, require repeated administration, in addition to the other hazardous effects associated with this route. Over the last few decades pharmaceutical scientists throughout the world are trying to explore transdermal and transmucosal routes as an alternative to injections. Historically, oral transmucosal drug delivery has received intensive interest since ancient times for the most widely utilized route of administration for the systemic delivery of drugs. In more recent years, better systemic bioavailability of many drugs has been achieved by oromucosal route. Among the various transmucosal sites available, soft-palatal mucosa was also found to be the most convenient and easily accessible novel site for the delivery of therapeutic agents for systemic delivery as retentive dosage forms, because it has abundant vascularization and rapid cellular recovery time after exposure to stress. Smooth surface of the soft palate and its good flexibility are prerequisites to prevent mechanical irritation and local discomfort. The objective of this review is to provide an update on the most promising advances in novel non-invasive soft-palatal route and the conceptual and technical approaches to the design and formulation of soft-palatal drug delivery systems. In this area, the development of mucoadhesive delivery systems appears to be the most promising strategy.

Orotransmucosal drug delivery systems: a review.

Oral mucosal drug delivery is an alternative method of systemic drug delivery that offers several advantages over both injectable and enteral methods and also enhances drug bioavailability because the mucosal surfaces are usually rich in blood supply, providing the means for rapid drug transport to the systemic circulation and avoiding, in most cases, degradation by first-pass hepatic metabolism. The systems contact with the absorption surface resulting in a better absorption, and also prolong residence time at the site of application to permit once or twice daily dosing. For some drugs, this results in rapid onset of action via a more comfortable and convenient delivery route than the intravenous route. Not all drugs, however, can be administered through the oral mucosa because of the characteristics of the oral mucosa and the physicochemical properties of the drug. Although many drugs have been evaluated for oral transmucosal delivery, few are commercially available. The clinical need for oral transmucosal delivery of a drug must be high enough to offset the high costs associated with developing this type of product. Transmucosal products are a relatively new drug delivery strategy. Transmucosal drug delivery promises four times the absorption rate of skin. Drugs considered for oral transmucosal delivery are limited to existing products, and until there is a change in the selection and development process for new drugs, candidates for oral transmucosal delivery will be limited. The present papers intend to overview a wide range of orotransmucosal routes being potentially useful for transmucosal drug delivery and remind us of the success achieved with these systems and the latest advancement in the field.

Asymmetric membrane in membrane capsules: a means for achieving delayed and osmotic flow of cefadroxil.

In the present study, both disintegrating and non-disintegrating polymeric capsular system in achieving delayed as well as improved osmotic flow for the model drug cefadroxil was developed. Asymmetric membrane in membrane capsule (AMMC) was prepared on a glass mold pin via phase inversion process in two steps. Step 1 included formation of a non-disintegrating, asymmetric membrane capsule (AMC) and step 2 involved formation of a pH sensitive, disintegrating, asymmetric membrane (AM) formed over the non-disintegrating membrane. The effects of different formulation variables were studied namely, level of osmogen, membrane thickness, and level of pore former. Effects of varying osmotic pressure, agitational intensity and intentional defect in the inner membrane on drug release were also studied. Membrane characterization by scanning electron microscopy showed dense regions with less pores on the outer surface of the disintegrating membrane and porous regions on the inner surface of the non-disintegrating asymmetric membrane. In vitro release studies for all the prepared formulations were done (n=6). The drug release was independent of pH, agitational intensity and intentional defect on the membrane but dependent on the osmotic pressure of the dissolution medium. The release kinetics followed the zero order and the mechanism of release was Fickian diffusion.