The assay of preparations containing pilocarpine and the characters of pilocarpine nitrate and hydrochloride / by H.D. Jowett.

  • Jowett, H. A. D. (Hooper Albert Dickinson)
Date:
[1899?]
Catalogue details

Licence: Public Domain Mark

Credit: The assay of preparations containing pilocarpine and the characters of pilocarpine nitrate and hydrochloride / by H.D. Jowett. Source: Wellcome Collection.

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    The specimen referred to by Paul and Cownley must have been very impure I am able to confirm the observations of other chemists that the pilocarpine nitrate of commerce is impure. Two specimens were examined by me from different manufacturers, and both yielded by recrystallisation about 85 p.c. of pure pilocarpine nitrate. The examination of these specimens gives the following results :— A. Melting point 167° . [a]n = + 77-88° B. Melting point 168° . [a]t> = + 7908° The impurity consisted of a crystalline nitrate of much lower melting point and specific rotatory pover. This would appear to be possibly pilocarpidine nitrate, but I am not in a position at present to state whether this is the case. Pilocarpine hydrochloride was prepared in the usual way through the base from pure pilocarpine nitrate, and then purified by repeated recrystallisation till the melting point aud specific rotatory power were unchanged by further treatment. The pure salt had the following physical constants:— Petit and Jowett. Polonowsky. Melting point = 204 ■— 205 . 200° [o]d +91-74° . +91° I attribute the higher figures obtained by me to the greater purity of the salt examined, as, though made from pure pilocarpine nitrate, it melted at 202°, but after recrystallisation at 204-205°. The hydrochloride described by Paul and Cownley as melting at 192°-196° must have been impure, but there is no reason to suppose that this impurity was different from that found in the nitrate, and stated to be pilocarpidine, as I have found that the nitrate of low melting point obtained from commercial pilocarpine nitrate yields a hydrochloride melting below 200° ; this would be a likely impurity. Having thus determined the physical constants of the pure substances I am able to suggest characters and tests for these salts. With regard to their purity I should not recommend that absolute purity be required, as the removal of the last traces of the other alkaloid requires an amount of recrystallisation out of pro¬ portion to the amount of impurity originally present. A nitrate melting at 175°-176° would not contain more than 1 per cent, of impurity, but would require three or more recrystallisations to be completely purified. I would therefore suggest the following characters and tests :— Pilocarpine Nitrate.—White distinct crystals, permanent in the