Selective Determination of Isoproterenol and Isoproterenol Sulfonic Acid in Pharmaceutical Dosage Forms

Improved, Rapid Spectrophotofluorometric Method for Assay of Isoproterenol Hydrochloride Injections: A Comparative Study

“…is also present in the samples of isoproterenol because both have nearly identical absorption maxima and because of the higher molar absorptivity of isoproterenone. Thus, both the USP XVIII method and the bis(2-ethylhexy1)phosphoric acid-ether extraction method (8) give false results when isoproterenone is also one decomposition product. As shown in Table 111, when 200 mcg./ml.…”

“…of isoproterenone was assayed by the fluorometric method, the final fluorescence was negligible. It can, therefore, be inferred that under these circumstances the new fluorometric method should be preferred over the USP XVIlI method or the bis(2-ethylhexy1)phosphoric acid-ether extraction method (8) to assay isoproterenol formulations.…”

“…TLC of simulated inhalations and injections stored in the dark over a period of 4 months showed that they consisted of decomposition products other than the sulfonic acid derivative of isoproterenol (8). Although the exact nature of these additionally encountered injections also contained a buffer consisting of lactic, acidsodium lactate, sodium.…”

“…These were stored at room temperature for several months and analyzed both by the fluorometric and USP XVIII procedures. In addition, the amount of isoproterenol sulfonic acid formed was estimated according to the method described by Kaistha (8) (Table IV). The close agreement between the two methods indicates that the fluorometric method is comparable to the USP XVIII method when the method is exactly followed, as indicated previously in this report.…”

Effects of Ascorbic Acid and Disodium Edetate on the Stability of Isoprenaline Hydrochloride Injection

“…Stabilizers used in isoprenaline injection include sodium metabisulphite (0.1%) which has been shown by biological assay to be effective in retarding the oxidation of heatsterilized isoprenaline solutions (0.01%) in ampoules (3). However, isoprenaline interacts with bisulphite ions to form isoprenalinesulphonic acid, which is pharmacologically inactive (4)(5)(6). The antioxidant synergist disodium edetate (0.01%) was not effective as a stabilizer for isoprenaline spray although it did protect phenylephrine eye-drops from oxidation (7).…”