Biomedical subjects

H M El-Banna

Publications and source records attributed to H M El-Banna.

5 recordsLinked to original sources

PubMed1978

Aspirin stability in solid dispersion binary systems.

The stability of aspirin in its solid dispersion with urea or povidone was investigated at two accelerated storage conditions. The observed aspirin degradation in both systems followed the first-order rate equation. The water sorption ability of the two carriers as well as the alkalinity imparted by urea could possibly be the most important factors responsible for the observed acceleration of aspirin decomposition. The results also showed that the temperature effect was more pronounced than the humidity effect. Generally, coprecipitated samples exhibited slightly higher degradation rates than physically mixed ones.

Aspirin↗

PubMed1975

Dissolution studies on paracetamol solidified melt prepared under different cooling rates.

Regulating the cooling rate of paracetamol melt resulted in the formation of different microcrystalline structures of the solidified melt. Dissolution rate studies were carried out on powdered samples prepared from fused paracetamol that was crystallized under different conditions. Rapid cooling associated with stirring the melt during crystallisation produced a fast rate of dissolution in the order of two times greater than the untreated drug. Increased dissolution rate data were masked to some extent when working with tablets prepared from the corresponsing solidified and powdered melts. The present study represent a new method of physical modification of drugs as a means of increasing rate of drug dissolution and absorption.

Acetaminophen↗

PubMed1975

The effect of crystal forms of some barbiturates on their pharmaceutical properties. Part 1: Phenobarbitone.

Up to 13 polymorphic forms of phenobarbitone have been reported in the literature. By melting the commercial sample and cooling under specified controlled conditions, three polymorphic forms II, II, XII, and a mixed form of II and III were obtained. The interconversion of the different forms was studied by special procedures including suspension in water, heating, and heavy dry grinding. The hydrated form XIII and a new hydrated one, designated XIV, were produced by suspending different other forms in water. Heating was found to affect transformation from any form to form I. IR spectroscopy and hot stage microscopy were used for the identification of the different polymorphic forms. Initial dissolution rate studies were carried out on only five forms. The dissolution rate constants were in the following decreasing order: II greater than III greater than I greater than XIV greater than XIII. Form II was found to dissolve at a rate constant about twice that of both hydrated forms.

Chemical Phenomena↗

PubMed1975

Physicochemical study of drug binary systems. Part 3: Tolbutamide-urea and tolbutamide-mannitol systems.

The phase diagram of the tolbutamide-urea system, constructed by data obtained from the microheating table apparatus, was a peritectic type. It showed the possibility of the formation of two molecular compounds with incongruent m. p. at 112 degrees C and 123 degrees C. Metastable and stable eutectic points were observed at 63 degrees C and 92 degrees C respectively. The phase diagram of tolbutamide-mannitol system revealed that in addition to eutectic liquefaction at 102 degrees C and 6% (w/w) mannitol, there was a region [40--80% (w/w) mannitol] in which the two components were not completely miscible in the liquid state. Solubility studies showed an increase of about 2.5 fold in the solubility of tolbutamide with 0.5 g% urea and suggested the possibility of the formation of a low-solubility complex in addition to a soluble higher complex of the two components. No obvious increase in the solubility of tolbutamide was detected in the presence of mannitol. A full description of the nature and composition of the final solidified melts of the two present systems could prove to be helpful in the explanation of the dissolution behaviour of the different studied samples and their corresponding physical mixtures. The fused 90% urea and mannitol solid dispersions showed a fast rate of dissolution in the order of 15 and 10 times (respectively) greater than pure tolbutamide.

Chemical Phenomena↗

PubMedDate not supplied

The application of solid dispersion technique in the preparation of therapeutic tablets. Part 1: Paracetamol, amylobarbitone, and caffeine tablets.

A trial was made to study the possibility of preparing high-quality therapeutic tablets by direct compression of the solidified drugcarrier melt via solid dispersion technique. Paracetamol-mannitol, amylobarbitone-urea and caffeine-nicotinamide systems were investigated. Phase diagrams of the first two systems were found to be of the simple eutectic type, while that of the third system was a peritectic type. Solubility studies were also carried out. Dissolution rate studies showed that the fused mannitol/paracetamol (80:20), urea/amylobarbitone (80:20) and nicotinamide/caffeine (50:50 and 70:30) solid dispersions exhibited better rates of dissolution than those of the pure drugs. Comparative studies were carried on with tablets prepared by direct compression of the drug-carrier solidified melt exhibiting the highest dissolution rate and by slugging the pure drug and the drug-carrier physical mixture of corresponding composition. The physical properties and dissolution rate data showed the superiority of the tablets prepared by the solid dispersion technique. The drug release from these tablets was 4.5, 7.6 and 3.7 times greater than that from tablets prepared from pure paracetamol, amylobarbitone and caffeine respectively.

Acetaminophen↗