Intestine Lab Report

1. INTRODUCTION
Oral drug administration is by far the most preferable route for taking medications. However, their short circulating half-life and restricted absorption via a defined segment of intestine limits the therapeutic potential of many drugs. Such a pharmacokinetic limitation leads in many cases to frequent dosing of the medication to achieve therapeutic effect. This results in pill burden and consequently, patient complains. The phenomenon of absorption via a limited part of the GIT has been termed the narrow absorption window; once this dosage form passes the absorption window the drug will be neither bioavailable nor effective. In extreme cases drugs that are insufficiently absorbed due to narrow absorption window cannot be delivered

Gastrointestinal utility and emptying of food:
The process of gastric emptying occurs both during fasting and fed states, however the pattern of motility differs markedly in the two states. During fasting state an interdigestive series of electrical events take place, which cycle both through the stomach and intestine every 2 to 3 hours (Table 1.1). This is recognized as interdigestive myeloelectric cycle or migrating myeloelectric cycle (MMC), which is further divided into four consecutive phases as explained by Wilson and Washington (Wilson CG, 1989).
 Phase I (Basal phase), the quiescent period, lasts from 40 to 60 minutes and is characterized by a lack of secretary, electrical and contractile activity.
 Phase II (Preburst phase) lasts for 40 to 60 minutes with intermittent action potential and contractions. As the phase progresses, the intensity and frequency also increases gradually.
 Phase III (Burst phase) is a short period of intense large regular contractions, termed as ‘house keeper waves’ that sweep off undigested food and lasts for 4 to 6

Ninan Ma et al., (2013) developed a type of multi-unit floating alginate (Alg) microspheres by the ionotropic gelation method with calcium carbonate (CaCO3) being used as gas-forming agent.
Parmar et al., (2011) prepared floating microspheres of acyclovir to prolong residence time in stomach and to sustain the release of acyclovir.
Masareddy et al., (2011) developed the floating alginate based microsphere system of Metformin HCL.
Sharma et al., (2011) developed a multiparticulate floating pulsatile drug delivery system using porous calcium silicate and sodium alginate, for time- and site-specific drug release of meloxicam.
Reddy et al., (2011) developed the floating microspheres of Cyclobenzaprine HCl by emulsion solvent diffusion technique using Ethyl cellulose polymer to achieve an extended retention in upper GIT and there by improved bioavailability.
Streubel et al., (2011) developed floating microparticles composed of polypropylene foam, Eudragit S, ethyl cellulose (EC), and polymethyl metha acrylate (PMMA) and were prepared by solvent evaporation