In response to some inquiries received by this department concerning the use of homatropine and paredrine (4-hydroxy-α-phenyl-β-aminopropine; β-4-hydroxylphenylisopropylamine) at various ph levels, we investigated their solubility and reaction in buffer solutions. Homatropine hydrobromide and paredrine hydrobromide1 were employed in concentrations of 5 per cent and 2 per cent respectively. The buffer solutions were prepared according to Gifford.2 All ph determinations were made by means of a glass electrode.
In the ph range investigated (4.20 to 8.75) the solutions remained perfectly clear after addition of the drugs. A slight alteration in the reaction of the buffer, varying from 0.05 to 0.35 ph unit, was noted. The
greatest changes occurred in the more alkaline solutions. At ph levels above 6.15 the shift was to the acid side, whereas at ph 4.6 the solution became slightly more alkaline.
Buffer solution no. 1,2 used as
John G. Bellows, Herman Chinn. SOLUBILITY OF DRUGS IN BUFFER SOLUTIONS. Arch Ophthalmol. 1941;25(2):333–334. doi:10.1001/archopht.1941.00870080157012