The colon is a site where both local and systemic delivery of drugs can take place. Local delivery allows topical treatment of inflammatory bowel disease. However, treatment can be made effective if the drugs can be targeted directly into the colon, thereby reducing the systemic side effects. This review, mainly compares the primary approaches for CDDS (Colon Specific Drug Delivery) namely prodrugs, pH and time dependent systems, and microbially triggered systems, which achieved limited success and had limitations as compared with newer CDDS namely pressure controlled colonic delivery capsules, CODESTM, and osmotic controlled drug delivery which are unique in terms of achieving in vivo site specificity, and feasibility of manufacturing process.

Transdermal drug technology specialists are continuing to search for new methods that can effectively and painlessly deliver larger molecules in therapeutic quantities to overcome the difficulties associated with the oral route, namely poor bioavailability due to hepatic metabolism (first pass) and the tendency to produce rapid blood level spikes (both high and low). Transdermal delivery can improve the therapeutic efficacy and safety of drugs by more precise (i.e., site-specific) way but spatial and temporal placement within the body is required to reduce both the size and number of doses necessary to achieve the objective of systemic medication through topical application to the intact skin surface. Modulation of formulation excipients and addition of chemical enhancers can increase drug flux but that is not sufficient to ensure delivery of pharmacologically effective concentration of drug therefore, several new active rate controlled TDDS technologies (electrically-based, structure-based, velocity-based, etc.) have been developed and commercialized for the transdermal delivery of 'troublesome' drugs. This review article covers most of the new active transport technologies involved in enhancing the transdermal permeation into an effective DDS. In-depth analysis, formulation approaches, applications, advantages and disadvantages of these newer technologies are discussed.

A multiple unit, non-disintegrating asymmetric polymeric capsular system was used to deliver highly water-soluble drug in a controlled manner. A highly water-soluble drug, metformin hydrochloride (MHCl), was selected as a model drug to demonstrate how the controlled release could be generated in vitro by changes in the core as well as the coating formulation. Formation of asymmetric capsule wall membrane involved wet phase inversion process, in which the asymmetric membrane (AM) was precipitated on glass mold pins by dipping the mold pins into a coating solution containing the good and bad solvents for the polymer followed by quenching in an aqueous quench bath. The study optimized by 23 factorial design evaluates the influence of coating formulation namely concentration of ethylcellulose and pore former (glycerol) and core component namely controlled release potassium chloride crystals. Scanning Electron Microscopy (SEM) showed the presence of outer dense non porous region and inner, thick, porous region for the prepared AM. Statistical test were applied at P > 0.05 on all the formulations undergoing in vitro release studies. Results showed the solubility of MHCl to have been modulated (reduced) over an extended period of time with pH independent, and osmotic pressure dependant drug release. The release kinetics was found to be zero order.

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Drugs for several diseases are still given without regard to the time of the day. Variation in dosing time is generally related with the effectiveness and toxicity of many drugs. On the other hand, several drugs affect the circadian clock. The knowledge of interactions between the circadian clock and drugs is valuable in clinical practice. The pharmacodynamics and pharmacokinetics of the medication influence the chronopharmacological phenomena and recent advances in it have made the traditional goal of pharmaceutics rather outdated. Enhanced progress in chronopharmacotherapy can be achieved if an identification of a rhythmic marker for selecting dosing time is done. However, technology involved in development of drug delivery systems (DDS) that match the circadian rhythm, and the unraveling of the relationship between circardian clock and pathology may be the hindrance in its prosperity for now. The Chronopharmaceutical Drug Delivery System (CDDS) has emerged during the last decade as a possible drug delivery system against several diseases, which may lead to the creation of a sub-disciple of pharmaceutics to be explored called 'chronopharmaceutics'. The review addresses the approaches to this sub-discipline, call attention to potential disease-targets, identifies existing technologies, hurdles and future of chropharmaceuticals. Chronopharmaceuticals coupled with nanotechnology could be the future of DDS, and lead to safer and more efficient disease therapy in the future.