Formulation of Polyethylene Glycol ointment bases suitable for tropical and subtropical climates. II

Attention has been focused on the suitability of PEG ointment bases in tropical and subtropical regions. Penetrometer studies were carried out at 33, 37 and 50 degrees C respectively. Penetrometer experiments indicate that the type and amount of PEG will greatly affect the penentration time, and a large number of selected PEGs showed softening in the second month. Rotovisco experiments were conducted at 35 and 45 degrees C. Experiments conducted by Rotovisco at 35 degrees C indicate that PEG bases exhibit plastic flow and rheopexy, and there is an increase in yield values during the twelve months. Experiments worked out by Rotovisco at 45 degrees C reflected that an increase in temperature resulted in a decrease in rheopexy, viscosity, area of histeresis loop and yield values. Results obtained by the two methods demonstrate that PEG 4000 in the presence of equal amounts of PEG 400 has a good texture and might be a suitable ointment base for tropical and subtropical areas.