Sustained and controlled drug delivery system release the drug at a substantially steady rate of release per unit of time. However, there are instances where maintaining a constant blood level of a drug is not desirable. In such cases a pulsatile drug delivery may be more advantageous. 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. Diseases wherein PDDS are promising include asthma, peptic ulcer cardiovascular diseases, arthritis attention deficit syndrome in children, and hypercholesterolemia. PDDS can be classified into time controlled systems wherein the drug release is controlled primarily by the delivery system; stimuli induced PDDS in which release is controlled by the stimuli, like the pH or enzymes present in the intestinal tract or enzymes present in the drug delivery system and externally regulated system where release is programmed by external stimuli like magnetism, ultrasound, electrical effect and irradiation. The current article focuses on the diseases requiring PDDS, methodologies involved for the existing systems, current situation and future scope, recent advances in PDDS and PDDS product currently available in the market.

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Pulsatile Drug Delivery System-A Review

Hollow microspheres (microballoons), loaded with drug in their outer polymer shells, were prepared by a novel emulsion-solvent diffusion method. The ethanol:dichloromethane solution of drug (tranilast or ibuprofen) and an enteric acrylic polymer were poured into an agitated aqueous solution of polyvinyl alcohol that was thermally controlled at 40 degrees C. The gas phase generated in the dispersed polymer droplet by the evaporation of dichloromethane formed an internal cavity in the microsphere of the polymer with the drug. The drugs incorporated in the solidified shell of the polymer were found to be partially or completely amorphous. The flowability and packability of the resultant microballoons were much improved compared with the raw crystals of drug. The microballoons floated continuously over the surface of acidic dissolution media containing surfactant for greater than 12 h in vitro. The drug release behavior of the microballoons was characterized as an enteric property, and drug release rates were drastically reduced depending on the polymer concentration at pH 6.8.

Hollow Microspheres for Use as a Floating Controlled Drug Delivery System in the Stomach.

Background—Oxidative stress has been implicated in the pathogenesis of heart failure. However, direct evidence of oxidative stress generation in the human failing myocardium has not been obtained. Furthermore, the effect of carvedilol, a vasodilating &bgr;-blocker with antioxidant activity, on oxidative stress in human failing hearts has not been assessed. This study was therefore designed to determine whether levels of lipid peroxides are elevated in myocardia of patients with dilated cardiomyopathy (DCM) and whether carvedilol reduces the lipid peroxidation level. Methods and Results—Endomyocardial biopsy samples obtained from 23 patients with DCM and 13 control subjects with normal cardiac function were studied immunohistochemically for the expression of 4-hydroxy-2-nonenal (HNE)-modified protein, which is a major lipid peroxidation product. Expression of HNE-modified protein was found in all myocardial biopsy samples from patients with DCM. Expression was distinct in the cytosol of cardiac myocytes. Myocardial HNE-modified protein levels in patients with DCM were significantly increased compared with the levels in control subjects (P <0.0001). Endomyocardial biopsy samples from 11 patients with DCM were examined before and after treatment (mean, 9±4 months) with carvedilol (5 to 30 mg/d; mean dosage, 22±8 mg/d). After treatment with carvedilol, myocardial HNE-modified protein levels decreased by 40% (P <0.005) along with amelioration of heart failure. Conclusions—Oxidative stress is elevated in myocardia of patients with heart failure. Administration of carvedilol resulted in a decrease in the oxidative stress level together with amelioration of cardiac function.

Carvedilol Decreases Elevated Oxidative Stress in Human Failing Myocardium

The present investigation deals with the formulation and evaluation of sodium alginate and pectin based In situ gel of Losartan Potassium. Sodium alginate and guar gum were used as a polymer and CaCO3 was used as a crosslinking agent. The formulation of gel depends upon factors like temperature modulation, pH changes, presence of ions and ultra-violet irradiation, from which drug gets released in sustained and controlled manner. The objective of this study was to develop a novel in- situ gel. The system utilizes polymers that exhibit sol-to-gel phase transition due to change in specific Physico-chemical parameters. In-situ gel was formed at a biological pH. In vitro release studies were conducted in simulated gastric fluid and cumulative amount of drug release was analyzed by spectrophotometry. From designed set of experiments, it was evident that formulation containing 2% of sodium alginate and 1.5% of Guar gum control the release of drug for longer duration. The in-situ gel exhibited the expected, viscosity, drug content, pH, in vitro gelling capacity, in vitro floating ability and sustained drug release. The drug release from the in situ gels follows the Fickian diffusion type of release.

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Formulation and evaluation of floating in situ gelling system of losartan potassium

Among the HIV / AIDS infected, individuals contract fungal infections of which many die as a direct consequence of these infections. In this study, the antifungal activity of ten extracts (stem bark) from Terminalia mantaly H. Perrier was evaluated on the in vitro growth of clinical isolate of pathogenic fungi (Cryptococcus neoformans). Agar double dilution method in slope tubes was adopted to determine anticryptococcal activity. All extracts exhibited antifungal activity in dose-response relationship. The residue extracts T4-2 obtained after degreasing the hydro-alcoholic extract T0 (MFC = 24.37μg/Ml; IC50 = 5.87μg/mL) is the most active extract. Moreover, for a given concentration it is said that there are not significant differences between the different tests for each extract (P< 0.05). Therefore, using the hydro-alcoholic solvent (70% ethanol) followed by removal of oil is the best way to obtain an optimally concentrated Research Article International Journal of Biochemistry Research & Review, 3(1): 63-73, 2013 64 active ingredient from Terminalia mantaly. The present study justifies the traditional use of this plant for the treatment of fungal infections.

Antifungal Activity of Terminalia mantaly on the in vitro Growth of Cryptococcus neoformans

DNA Microarray is the emerging technique in Biotechnology. The many varieties of DNA microarray or DNA chip devices and systems are described along with their methods for fabrication and their use. It also includes screening and diagnostic applications. The DNA microarray hybridization applications include the important areas of gene expression analysis and genotyping for point mutations, single nucleotide polymorphisms (SNPs), and short tandem repeats (STRs). In addition to the many molecular biological and genomic research uses, this review covers applications of microarray devices and systems for pharmacogenomic research and drug discovery, infectious and genetic disease and cancer diagnostics, and forensic and genetic identification purposes.

Patel Gv

Papers

International Journal for Pharmaceutical Research Scholars (IJPRS)