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Pulsatile drug delivery systems (PDDS) are gaining importance as these systems deliver the drug at specific time as per the pathophysiological need of the disease, resulting in improved patient therapeutic efficacy and compliance. These systems are beneficial for the drugs having chronopharmacological behaviour (where night time dosing is required), firstpass effect and having specific site of absorption in gastro intestinal tract (GIT). From the viewpoint of therapeutic optimization, maintaining a constant blood level for a drug in the human body is questionable.1) Long-term constant drug concentration exposed in blood and tissues may induce many problems such as tolerance of drug and activation of physiological system.2) Recently, chronotherapy has been extensively applied in clinical therapy by modulating the dosing regimen of drug administration according to physiological needs.3) Diseases wherein PDDS are promising include asthma, peptic ulcer, cardiovascular diseases, arthritis, and hypercholesterolemia. The pathophysiology of arthritis and patients with osteoarthritis tend to have less pain in the morning and more at night; while those with rheumatoid arthritis, have pain that usually peaks in the morning and decreases throughout the day. 4)A dry-coated tablet was recently renewed as a novel system to deliver a drug in a pulsatile way, at predetermined times following oral administration. 4,5) This novel system is not only rate controlled but is also time controlled. The dry-coated tablets were prepared by a direct compression method. This compression method eliminates the time-consuming and complicated coating or granulation processes and also improves the stability of the drug by protecting it from moisture. 6)There are various problems with pH dependent drug delivery; however the pH in the gastrointestinal tract varies between and within individuals. [7][8][9] It is affected by diet and disease.10) During acute stage of inflammatory bowel disease colonic pH has been found to be significantly lower than normal.11) In ulcerative colitis pH values 2.3-4.7 have been measured in the proximal parts of the colon.12)The purpose of this study was to develop press coated tablets for pulsatile drug delivery of ketoprofen. The oral press coated tablet was developed to achieve the time-controlled disintegrating or rupturing function with a distinct predetermined lag time. Press-coated tablet containing ketoprofen and other excipients in the inner core was formulated with an outer shell by different weight ratios of hydrophobic polymer (micronized ethylcellulose powder) and hydrophilic polymers (glycinemax husk, sodium alginate). Ethylcellulose (EC) is a well-known water-insoluble polymer that has been used as a rate-controlling membrane to regulate drug release. EC powder with different micronized sizes has been directly compressed to form compact EC in which plastic deformation is the predominant consolidation mechanism.13) Glycinemax containing dry matter (DM), crude protein (CP), crude fiber (CF), ether extract ...

The aim of the present study was to develop fast-release enteric-coated tablets for pulsatile drug delivery to the colon. The novelty of this work is a combination of pH- and time-dependant enteric polymers as a single coating. Eudragit S100 was used as a pH-dependant polymer and eudragit RL100 was used as a time-dependant polymer. Theophylline was taken as a model drug. Dissolution studies of enteric-coated tablets were performed with different media having a pH of 1.2, 7.4, and 6.8. Results of the dissolution data show that drug release in the colon could be controlled by using eudragit RL100 eudragit S100. The lag time prior to the drug release was highly affected by a combination of two factors: The percentage of eudragit RL100 and coating level. The optimum formulation was found to be one containing eudragit RL100 and eudragit S100 with a ratio of 60:40 of polymer and coating level of 4.66% w/w. The present study demonstrates that the theophylline enteric-coated tablets could be successfully formulated as a pulsatile drug delivery by the design of a time- and pH-dependant modified chronopharmaceutical formulation. In conclusion, pulsatile drug release over a period of 2-12 hours, consistent with the requirements for chronopharmaceutical drug delivery, can be achieved by using time- and pH-dependant polymers.

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an online international journal allowing free unlimited access to abstract and full-text of published articles. The journal is devoted to the promotion of health sciences and related disciplines (including medicine, pharmacy, nursing, biotechnology, cell and molecular biology, and related engineering fields). It seeks particularly (but not exclusively) to encourage multidisciplinary research and collaboration among scientists, the industry and the healthcare professionals. It will also provide an international forum for the communication and evaluation of data, methods and findings in health sciences and related disciplines. The journal welcomes original research papers, reviews and case reports on current topics of special interest and relevance. All manuscripts will be subject to rapid peer review. Those of high quality (not previously published and not under consideration for publication) will be published without delay. The maximum length of manuscripts should normally be 10,000 words (20 single-spaced typewritten pages) for review, 6,000 words for research articles, 3,000 for technical notes, case reports, commentaries and short communications. Submission of Manuscript:The International Journal of Health Research uses a journal management software to allow authors track the changes to their submission. All manuscripts must be in MS Word and in English and should be submitted online at http://www.ijhr.org. Authors who do not want to submit online or cannot submit online should send their manuscript by e-mail attachment (in single file) to the editorial office below. Submission of a manuscript is an indication that the content has not been published or under consideration for publication elsewhere. Authors may submit the names of expert reviewers or those they do not want to review their papers. Enquiries Original Research Article Effect of Curing Time on pH and Time Dependant Coated PelletsReceived: 29-Dec-08Revised: 10-Jan-09 Accepted: 11-Jan-09Abstract PURPOSE: The drug release from coated pellets depends on many process and formulation variables, including plasticization, curing treatment, and properties of the core. In this study, effect of currying on eudragit coated pellets was investigated. METHODS: Theophylline loaded pellets were coated with a non aqueous time and pH dependant eudragit solution. The coated pellets were cured at constant process parameters (45°C) for different time periods (05, 10, or 20 min) and the drug release profile and other characteristics of formulation were evaluated. RESULTS:In vitro release studies shows retardation of drug release from the coated pellets. The DSC thermogram revealed no interaction between the polymer and drug in the formulation. The SEM data shows no change in the surface topography after 20 min curing. CONCLUSION:In general, curing reduced the drug release and resulted in stable drug release profiles.