Effect of some additives on the properties of phenazopyridine hydrochloride granules and their corresponding tablets.

The effect of the diluents, lactose and calcium carbonate and of the binders, syrup, gelatin, methylcellulose and Eudragit E on the physical properties of phenazopyridine hydrochloride (PNHCl) granules was evaluated. A correlation existed between the granules' physical properties and those of their compressed tablets. With regard to drug release, lactose-syrup 30% was the best of all diluent-binder combinations, followed by lactose-methylcellulose 4%. Also lactose was found to be superior to calcium carbonate in drug release when gelatin and methylcellulose were used as binders. Eudragit E was the best binder with calcium carbonate in this respect. On the other hand, the bioavailability of PNHCl in humans was the same when lactose was used with either gelatin, syrup or methylcellulose, but higher than that obtained with a combination of calcium carbonate and Eudragit E 15%.

The use of directly compressible vehicles for the preparation of vitamin B1 tablets.

The classical method for the preparation of vitamin B1 tablets led to tablets of doubtful and/or shorter stability. Dipac , Emdex , Nu-Tab and Sugartab , were evaluated as direct compression vehicles for the preparation of vitamin B1 tablets. Avicel was also employed as a traditional vehicle for comparison. These vehicles were evaluated at different concentrations compared with vitamin B1 tablets available in the Egyptian market and prepared by the classical method. Generally, it was found that increasing the concentration of the vehicles in the tested vitamin B1 formulations improved the physical standards and mechanical strength of the tablets produced. Avicel was found to be the most suitable vehicle, followed by Dipac and Emdex . However, Sugartab and Nu-Tab were found to be the worst in this respect.

Effect of liquid additives on release of chloramphenicol from ointment bases.

1, 3 and 5% water, ethyl alcohol, glycerol and propylene glycol were incorporated into oleaginous, absorption, emulsion (O/W and W/O) and water-soluble ointment bases (resp.) containing 5% of chloramphenicol and diffusion rate via the dialysis method was measured for 2 h. The rate of release was found to be greater from water-soluble bases than from the other bases, since rates from oleaginous, absorption and W/O emulsion bases were found to be the least in this respect. The effect of liquids added to these bases on drug release was found to be less pronounced than that obtained with water-soluble and O/W emulsion bases. For O/W emulsion bases the addition of ethyl alcohol increased the release of chloramphenicol as its concentration was increased. Propylene glycol increased the release at a concentration of 3%, but higher concentration produced opposite results. Glycerol was found to have a little effect in 5% concentration, but it increased the release as the concentration dropped to 3% concentration.