Interaction between phenylephrine hydrochloride and polyethylene glycol 400.

Evidence of complexing tendency of the water-soluble polymer polyethylene glycol 400 (PEG 400) and phenylephrine hydrochloride was supported by the equilibrium dialysis method. The influence of polymer concentration, ionic concentration, and hydrogen ion concentration of the systems on the interaction was investigated. Attempts to separate the complex by using paper chromatographic techniques have also been made.

Studies on the stability of injectable solutions of some phenothiazines. Part 1: Effects of pH and buffer systems.

The stability of phenothiazines is affected by the pH-value of the solution. At the pH-values of maximum stability, triflupromazine hydrochloride and chlorpromazine hydrochloride are more stable than promazine hydrochloride. The stability of chlorpromazine hydrochloride in the Sörensen's phosphate buffer is slightly higher than that in the McIlvaine's citric acid-phosphate buffer system. On the other hand, the stbility of promazine hydrochloride and triflupromazine hydrochloride in the latter buffer system is slightly higher than that in the former one.

Studies on the stability of injectable solutions of some phenothiazines. Part 2: Effect of chelating agents and antioxidants.

Chelating agents (disodium EDTA, DTPA, HEDTA and NTA) exhibit a stabilizing action towards phenothiazines to different extents. This could be correlated to the stability constants of their metal chelates as well as to the dependency of these constants on the pH-value of the solution. Antioxidants (sodium bisulphite, sodium dithionite, and sodium metabisulphite) also exert a stabilizing effect which could be correlated--in the first place--to the pH-value of the solution. The sulphur content of the antioxidant might also be relevant to such an effect.

On the racemization of L-noradrenaline bitartrate.

The hydronium ion catalyzed racemization of L-noradrenaline bitartrate solutions was studied as a function of ionic strength and polarity of the medium. On the grounds of the findings obtained, it was assumed that the racemization of the drug involves an ionic reaction between ions of like charge. The water/propylene glycol system dielektric constant 60 was found to furnish optimal stability conditions for the drug. In addition, attention must be given to avoiding the incorporation of electrolytes into the solution.

A paper chromatographic method for separation and determination of synephrine in injectable solutions.

A new analytical method using ascending paper chromatographic technique was developed for identification and quantitative determination of residual synephrine in fresh and deteriorated samples. This method was found to be stability indicating; one to five degradation products have been successfully separated from drug samples subjected to accelerated stability testing at 60 degrees C for 3 months.

Effect of urea on the activity of certain ophthalmic drugs in man.

The role displayed by urea (2-10%) solutions, on the miotic and mydriatic activities of pilocarpine hydrochloride and homatropine hydrobromide respectively, was investigated on the human eye. At different concentrations, urea exerts no effect on the miotic activity of pilocarpine, whereas in the case of homatropine a negative effect is experienced. For the parameters, area under pupil diameter--time curve (AUC) and maximum pupillary response (MPR), a linear relationship exists between response to homatropine and urea concentration. However, the dependency is more pronounced in conjunction with the MPR parameter.