Characteristics of Different Systems for the Solar Drying of Crops

Solar dryers are used to enable the preservation of agricultural crops, food processing industries for dehydration of fruits and vegetables, fish and meat drying, dairy industries for production of milk powder, seasoning of wood and timber, textile industries for drying of textile materials. The fundamental concepts and contexts of their use to dry crops is discussed in the chapter. It is shown that solar drying is the outcome of complex interactions particular between the intensity and duration of solar energy, the prevailing ambient relative humidity and temperature, the characteristics of the particular crop and its pre-preparation and the design and operation of the solar dryer

Development of an Optimised Losartan Potassium Press-Coated Tablets for Chronotherapeutic Drug Delivery

Purpose: To develop an optimised press-coated tablets of losartan potassium using an admixture of a hydrophilic polymer, hydroxypropylmethylcellulose (HPMC) and microcrystalline cellulose (MCC) in order to achieve a predetermined lag time for chronotherapy. Methods: The press-coated tablets (PCT) containing losartan potassium in the inner core were prepared by compression-coating with HPMC 100KM alone and admixed with MCC as the outer layer in different ratios. The effect of the outer layer on the lag time of drug release was investigated. The parameters determined were tablet tensile strength, friability, drug content and in vitro dissolution. The optimised formulation was further characterized with Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (PXRD) to investigate any drug/excipient modifications/interactions. Results: The tensile strength values of all the PCT were between 1.12 and 1.23MNm-2 and friability was < 0.36 %. The release profile of the press-coated tablet exhibited a distinct lag time before burst release of losartan potassium. Lag time was dependent on the ratio of HPMC/MCC in the outer shell. The lag time was from 0.5 to 18.5 h and could be modulated as it decreased as the amount of MCC in the outer layer increased. There was no modification or chemical interaction between the drug and the excipient. Conclusion: Formulation LPP2, with HPMC/MCC of (30:70) in the outer shell and showing a predetermined lag time of 6 h prior to burst release of the drug from the press-coated tablet was taken as the optimized formulation

Formulation of gastro-retentive floating tables of Diltiazem Hydrochloride wtih carnauba wax by melt granulation technique

The study was carried out to investigate drug release profile of gastroretentive drug delivery system (GDDS) of diltiazem hydrochloride prepared with a hydrophilic polymer (hydroxylpropyl methyl cellulose), hydrophobic polymer (ethyl cellulose) and a waxy material (carnauba wax). Drug profiles were compared with a commercial formulation of the drug (MKT). Sodium bicarbonate (30%) was incorporated as gas generating agent. Formulations were either prepared alone with the individual polymer or admixed with carnauba wax. Formulations containing carnauba wax were prepared by melt granulation technique. Tablets were evaluated for tensile strength, in vitro buoyancy and drug release profiiles. Release data were subjected to analysis by four different mathematical models namely, – zero order flux, first order, Higuchi square root of time relationship and Korsmeyer equations. All formulated tablets and MKT had tensile strength values between 1.05 - 1.32 MNm-2. One of the test formulations (F7) gave a comparable release profile with the commercial sample, MKT. For instance, the % maximum release (m∞) and time to attain this (t∞) for F7 and MKT were (96%, 99%) and (12, 12 h) respectively, while their dissolution rates (m∞/t∞) were 8 %h-1 and 8.3 %h-1 respectively. All the formulations fitted well into Korsmeyer and Peppas model (correlation coefficient r value ≥ 0.95). Release exponent (n) for F7 and MKT formulations were 0.150 and 0.286 respectively with a corresponding release rate constant values of 65.4 and 43.8. This showed that release of diltiazem hydrochloride from these formulations followed Fickian diffusion mechanism. An optimised GDDS of diltiazem hydrochloride using carnuba wax as a matrix, comparable with MKT has been developed. Keywords: Gastroretentive drug delivery system, melt granulation, floating, diltiazem hydrochloride, Carnauba waxJournal of Pharmaceutical and Allied Sciences, Vol. 7 No. 2 (2010

Chronobiology and Chronotherapy of Hypertension – A Review

Hypertension occurs in over 90% of all patients with cardiovascular disease (CVD) in the United States and it is a major risk factor for end-organ damage, CVD and death. In the treatment of hypertension, investigation of chronobiology, chronopharmacology and chronotherapy began a few decades ago. Studies over the last decade have revealed that blood pressure (BP) and CVD are influenced by our behaviour such as what we eat and even conditioned by the time of day. Also, the ability of the night: day ratio of systolic BP predicts the risk for cardiovascular events more accurately compared with office BP measured only at once. Evidence clearly points to the fact that nocturnal BP is indeed the BP as it is most consistently correlated with prediction of cardiovascular risk and provides more close surveillance of safety. Circadian rhythm is a significant input into the regulation of BP. Hence, a circadian disorder such as hypertension requires chronopharmacotherapy. However, different medications have been studied for their chronopharmacology and potential chronotherapy. This article reviews the chronobiology of hypertension, and the chronopharmacology and chronotherapy of the various medications used in its management.Keywords: Hypertension, Circadian rhythm, Chronobiology, Chronopharmacology, Chronotherapy

Development of an Optimised Losartan Potassium Press-Coated Tablets for Chronotherapeutic Drug Delivery

Purpose: To develop an optimised press-coated tablets of losartan potassium using an admixture of a hydrophilic polymer, hydroxypropylmethylcellulose (HPMC) and microcrystalline cellulose (MCC) in order to achieve a predetermined lag time for chronotherapy. Methods: The press-coated tablets (PCT) containing losartan potassium in the inner core were prepared by compression-coating with HPMC 100KM alone and admixed with MCC as the outer layer in different ratios. The effect of the outer layer on the lag time of drug release was investigated. The parameters determined were tablet tensile strength, friability, drug content and in vitro dissolution. The optimised formulation was further characterized with Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (PXRD) to investigate any drug/excipient modifications/interactions. Results: The tensile strength values of all the PCT were between 1.12 and 1.23MNm-2 and friability was < 0.36 %. The release profile of the press-coated tablet exhibited a distinct lag time before burst release of losartan potassium. Lag time was dependent on the ratio of HPMC/MCC in the outer shell. The lag time was from 0.5 to 18.5 h and could be modulated as it decreased as the amount of MCC in the outer layer increased. There was no modification or chemical interaction between the drug and the excipient. Conclusion: Formulation LPP2, with HPMC/MCC of (30:70) in the outer shell and showing a predetermined lag time of 6 h prior to burst release of the drug from the press-coated tablet was taken as the optimized formulation

Formulation and Evaluation of Gastro Retentive Floating Drug Delivery System for Propranolol HCl

The aim of the present investigation is to develop and optimize gastroretentive floating drug delivery systems for propranolol HCl. Propranolol HCl is an effective anti hypertensive drug, with a relatively short half life and is freely soluble in water. In the present work, propranolol HCl floating tablets were prepared with PEO WSR N-750 and PEO WSR 301 as release retarding agents and sodium bicarbonate as gas generating agent. Direct compression method was employed for the preparation of tablets; formulated tablets were evaluated for all physicochemical properties, in vitro buoyancy, rate order kinetics and dissolution studies. The optimised formulation was characterised through FTIR studies. From the results, PP 09 was selected as an optimized formulation based on the 12 h drug release, minimal floating lag time and maximum total floating time. The optimized formulation followed zero order rate kinetics with erosion mechanism. The optimized formulation showed no interaction between the drug and the polymers used in the formulation.Key words: Gastroretentive, floating, propranolol HCl, polyethylene oxide, in vitro buoyanc