PubMed Health⌕ Search

Biomedical subjects

H N Joshi

Publications and source records attributed to H N Joshi.

10 recordsLinked to original sources
PubMed2000

Study of phase behavior of poly(ethylene glycol)-polysorbate 80 and poly(ethylene glycol)-polysorbate 80-water mixtures.

Mixtures of poly(ethylene glycols) (PEGs) with polysorbate 80 are often used to dissolve poorly water-soluble drugs in dosage forms, where polysorbate 80 helps either in enhancing dispersion or in inhibiting precipitation of drugs once the solution is mixed with water. Binary phase diagrams of polysorbate 80 with several low molecular weight PEGs and a ternary phase diagram of polysorbate 80 with PEG 400 and water are presented. Two phases were observed in the binary mixtures when the concentration of PEG 200, PEG 300, PEG 400, or PEG 600 was >55%(w/w). The miscibility of the binary mixtures increases with an increase in temperature; the upper consolute temperatures of PEG 200-polysorbate 80, PEG 300-polysorbate 80, PEG 400-polysorbate 80, and PEG 600-polysorbate 80 mixtures were 100, 85, 75, and 40 degrees C, respectively. The upper consolute temperature of PEG 1000-polysorbate 80 could not be determined because the melting temperature of the mixtures is approximately 40 degrees C and the consolute temperature appeared to be less than this temperature. The decrease in upper consolute temperature with an increase in PEG molecular weight indicated a greater miscibility of the two components. In the ternary system, phase separation of polysorbate 80 was observed when the concentration of PEG 400 was >50-60 % (w/w), possibly because of the high exclusion volume of PEG 400.

Dosage Forms↗
PubMed1995

Calorimetric evaluation of hydration of cholestyramine.

We have investigated the mechanism of hydration of cholestyramine, a water-insoluble resin used pharmaceutically. Two types of water of hydration (freezing and non-freezing) and the amounts of heat evolved or absorbed during the hydration of cholestyramine were determined. From differential scanning calorimetry, 0.57 g water was observed to be tightly bound per gram of resin (non-freezing water). The hydration of dry cholestyramine was found to be exothermic. The heats of hydration of cholestyramine with chloride or nitrate counter-anions were found to be -6.05 and -3.46 cal g-1, respectively. Some of the partially hydrated cholestyramine samples showed absorption of heat during hydration. The data generated in the study were utilized to better understand the mechanism of hydration and swelling of cholestyramine.

Calorimetry, Differential Scanning↗
PubMed1993

Calorimetric studies of dissolution of hydroxypropyl methylcellulose E5 (HPMC E5) in water.

The interaction of water with polymers is important because it directly or indirectly affects various properties such as rheological and transport properties. In this study, the hydration/dissolution of a hydrophilic polymer was investigated by calorimetric techniques. Hydroxypropyl methylcellulose E5 (Methocel, HPMC E5) was used as the model polymer. A water-insoluble, hydrophobic polymer, ethyl cellulose E4 (Ethocel, EC E4), was selected for comparison. The number of moles of non-freezing and freezing water were determined by differential scanning calorimetry. Moles of non-freezing water per polymer repeat unit were 6.2 +/- 1.3 and 1.6 +/- 0.3 for HPMC E5 and EC E4, respectively. The hydration/dissolution of HPMC E5 was exothermic, with a total heat of dissolution of -24.1 +/- 1.1 cal/g (n = 4). The heat of hydration of water-insoluble EC E4 was -2.6 cal/g (n = 2). The specific heat capacity value of HPMC E5 increased due to the addition of water. The heat of solution and an increase in specific heat capacity values were associated mainly with the addition of tightly bound water to the polymer. The dissolution of HPMC E5 in water is believed to have endothermic and exothermic components. In summary, the study provided insight into the dissolution of a representative hydrophilic polymer in water. The heat of solution and the specific heat capacity values were mainly dependent on the addition of tightly bound water.

Calorimetry↗
PubMed1990

Aarskog syndrome. A case report.

A rare Aarskog syndrome is reported in a 12-year-old boy. The patient had a triad of characteristic symptoms consisting of short stature, genital anomaly, and unusual facies. Both jaws were hypoplastic with presence of crowded permanent teeth and over-retained deciduous teeth. Radiographic examination of teeth showed taurodontism, which has not been reported previously.

Abnormalities, Multiple↗
PubMedDate not supplied

Facial myiasis: report of case.

A report is described in which a young Indian girl had a large round facial ulcer near the mandible, with maggots observed in four burrows within the ulcer. Turpentine oil was applied to each burrow; debridement and irrigation permitted healing to occur rapidly.

Child, Preschool↗