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Accurate, rapid and sensitive extraction-colorimetric method for the determination of erythromycin and its esters, depending on the formation of an ion-pairs with chromotropic acid (I), chromotrope 2B (II), chromotrope 2R (III), arsenazo I (IV), arsenazo III (V), benzocaprol red (VI) and acid ethyl blue (VII) is described. The calibration curves resulting from the measurements of absorbance-concentration relations (at the optimum reaction conditions) of the extracted ion-pairs are linear over the concentration range 0.4-56 μgm1[SUP-1] with a relative standard deviation (RSD) of 1.3% for 25 μgml[SUP-1] erythromycin. The detection limit, quantification limit, the molar absorptivity and Sandell sensitivity for erythromycin ion-pairs were evaluated. The interference from excipients commonly present in dosage forms and common degradation product was studied. The method is highly specific for the determination of stearate and succinate esters in dosage forms. The method has been compared to the official method and found to be simple, accurate (t-test) and reproducible (F-test). The developed method was applied for bulk drug, esters and some of their dosage forms without interferences from additives and excipients. [ABSTRACT FROM AUTHOR]

Chlortetracycline was successfully separated from its degradation products and from other tetracyclines on a paper chromatogram previously impregnated with a mixture of edetate disodium and urea solution in pH 5.0 McIlvaine buffer. Chlortetracycline separation from its degradation products and from both tetracycline and oxytetracycline was attributed primarily to the complexation of these antibiotics with urea and edetate on the chromatogram. The separated spots were located under UV light, and their Rf values were calculated. Chlortetracycline recovery from the paper chromatogram was satisfactory (98.3 +/- 0.002%). The developed method was successfully applied to the determination of chlortetracycline in various dosage forms. In addition, the method was adequate for monitoring chlortetracycline hydrochyloride stability in aqueous solutions.

A reverse phase paired ion liquid chromatographic procedure is described for determining methscopolamine bromide (Pamine) in the presence of neomycin sulfate in 5 veterinary formulations (Biosol M). Methscopolamine bromide is separated from neomycin sulfate and other formulation excipients by extraction into ethanol. The sample preparations are then concentrated and dissolved in water before chromatography. Recovery of methscopolamine bromide added to 5 placebo formulations ranged from 99.7 to 100.7%, with relative standard deviations of less than 2%. Specificity of the method with regard to potential degradation products is demonstrated.

A simple method, requiring no chromatographic separation, is presented for the determination of the total and non-phenolic alkaloids in ipeca and its preparations. The complex formed between the alkaloid and methyl orange at pH 5.0 is extracted with chloroform and treated with 0.1N NaOH. The liberated dye, determined at 460 nm, is a measure of the total alkaloids. The chloroform phase remaining is treated with 0.1N H2SO4, and the acid extract is measured at 283 nm for the non-phenolic alkaloids, calculated as emetine. The proposed method was successfully applied to samples of ipeca powder, ipeca tincture, and 3 British Pharmaceutical Codex mixtures containing ipeca tincture, namely, ipecacuanha mixture, pediatric; ipecacuanha and ammonia mixture, pediatric; and belladonna and ipecacuanha mixture, pediatric. The proposed method compares favorably with the Egyptian Pharmacopoeia, British Pharmacopoeia, and USP methods and has a relative standard deviation of 1.54%. The present procedure is less time-consuming and requires about 45 and 90 min for the assay of ipeca tincture and powder, respectively. Only a small sample (0.2 mL tincture of 1.0 g powder) is required.

The suitability of isotachophoresis for the determination of quinine in different samples was investigated. The operational conditions were 0.01 M potassium-morpholinoethanesulphonic acid (MES) (pH 6.0) with 0.05% Mowiol as the leading electrolyte and ca. 0.005 M creatinine-MES as the terminating electrolyte. The analyses were carried out at 25 microA in a 0.2 mm I.D. PTFE capillary with UV and conductivity detection. Quinine-containing beverages were degassed by sonification and directly injected. The limit of detection was 5 mg/l with a 4 microliter injection volume. The allowed concentrations could be determined with sufficient accuracy. Analgesic preparations were dissolved in a solution of 5 X 10(-3) M MES with sonification. The quinine levels found agreed well with the declared values. The other constituents of the pharmaceuticals did not interfere with the analysis. Urine samples from volunteers were analysed after consumption of tonic. The samples were extracted with dichloromethane-isopropanol (95:5), vortexed, centrifuged, evaporated to dryness, the residue dissolved in 5 X 10(-3) M MES and analysed. At a concentration factor of 33, the limit of detection was ca. 60 micrograms in 48-h urine: 2-15% of the quinine consumed was excreted as the parent compound in the first 48 h after consumption. The combination of the extraction procedure and the operational system makes the method suitable for the determination of a number of other alkaloids in physiological samples.

This review summarizes the nature of acute fluoride toxicity, its time-course, and the fluoride doses that are involved. The generally accepted "certainly lethal dose" range for 70 kg adults, i.e., from 5 to 10 g of sodium fluoride or from 32 to 64 mg fluoride/kg, is discussed. Based on recent case reports of fluoride-induced fatalities, it is concluded that this dose range has little utility in cases involving young children. The concept of a "probably toxic dose" (PTD) is advanced. The PTD, 5.0 mg F/kg, is defined as the dose of ingested fluoride that should trigger immediate therapeutic intervention and hospitalization because of the likelihood of serious toxic consequences. The concentrations and quantities of fluoride in selected dental products are discussed in relation to the PTD. It is concluded that, as these products are currently packaged, most of them contain quantities of fluoride sufficient to exceed the PTD for young children. Recommendations are made to reduce the risk of toxicity associated with their use.

Eight laboratories collaboratively studied a procedure for the quantitative determination of methaqualone. HC1 in pharmaceutical and clandestine preparations. Methaqualone is extracted from an aqueous bicarbonate solution into chloroform and quantitated by gas-liquid chromatography on a 3% OV-1 column. Tetraphenylethylene is used as an internal standard. Two commerical preparations and 4 sample mixtures prepared by the author were studied. Recoveries for the 4 prepared samples ranged from 100.0 to 102.6%, and the coefficients of variation ranged from 1.58 to 4.15% for the 6 samples studied. The method has been adopted as official first action.

Enteric coated commercial dosage forms often do not correspond with acid resistance and disintegration requirements of the Ph. Eur. About 15-20% of 181 tested samples disintegrate during acid resistance test or do not disintegrate in buffer solution pH = 6.8. The percentage was extremely high amongst enteric coated pancreatin or cardiac glycosides (about 30%) preparations. Storage conditions and time influence acid resistance and disintegration time. 80% of 34 products coated with celluloseacetate phthalate, hydroxypropylmethylcellulose phthalate or polymethacrylic acid ester did not change disintegration time after 2 years storage at 20 degrees C. After storage at 40 degrees C the number decreased to 40%. After 5 years at 20 degrees C number of products which were not stable increased.

A new spectrophotometric method has been developed for determining diphenhydramine. HC1, based on solvent extraction into chloroform of the complex formed with bromocresol green. The complex solution in chloroform showed maximum absorption at 415 nm and obeyed Beer's law over the concentration range of 3.0-12.0 microgram/ml. The molar absorptivity of the complex was 2.02 x 10(4). Complex formation and extraction was complete and quantitative over the pH range from 2 to 5. The ratio of diphenhydramine to bromocresol green was 1:1. Excipients, coloring matter, flavoring agents, and other substances likely to be present in diphenhydramine preparations do not interfere in the determination. Direct determinations in tablet, capsule, sirup, and lotion preparations were carried out satisfactorily, and the average recovery was 100 +/- 1.0%.

A method is developed for the simultaneous determination of neopynamine and piperonyl butoxide by chromatography on a quartz capillary column using flame ionization detection. Benzyl mandelate is used as an internal standard. Calibration graphs are linear down to at least 3.75 mg% and 3 mg% for neopynamine and piperonyl butoxide, respectively.

1,3-Dibromodimethylhydantoin (DBH) is a stable dihalogen reagent. It can be used as an analytical reagent for certain analgesics. It gives stoichiometric results by direct titration in acid medium. The end point is detected visually or potentiometrically. Also spectrophotometric titrations have been attempted at 345 nm. In all cases the results of the analysis of the drugs studied either in the pure state or in their dosage forms comply with those given by N-bromo succinimide (NBS) and by the official methods, however this application is distinguished by simplicity and accuracy.

Ten benzodiazepines--clorazepate, nitrazepam, clonazepam, oxazepam, lorazepam, chlordiazepoxide, N-desmethyldiazepam, diazepam, prazepam, and flurazepam--in solid dosage form are identified by ultraviolet (UV) and infrared (IR) spectrophotometry and by high pressure liquid chromatography (HPLC). UV absorption data and IR spectra of the 10 benzodiazepines are provided and HPLC separation methods are described.

A method is described for the isolation and identification of propantheline bromide from bulk drug substances and dosage forms, both alone and in combination with other drug substances. The method permits the specific identification of the intact drug substance, using both infrared spectroscopy and thin layer chromatography.

Chemical an physical properties of film coating materials determine stability of enteric coated pharmaceutical dosage forms. About 80% of commercial enteric coated drugs with coatings of celluloseacetate phthalate or polymethacrylic acid ester did not change acid resistance or disintegration time after 2 years, storage at 20 degrees C or 40 degrees C. Disintegration time of 4 drugs which are enteric coated with hydroxypropylmethylcellulose phthalate, decreased more often. Some of these did not fulfill acid resistance requirements of the Ph. Eur., tests which show influence of softeners to stability of enteric coatings have to be extended.

The quantitative determinations of phenol in phenolated calamine lotion USP and of phenol and resorcinol in phenol-resorcinol-boric acid solution by high-pressure liquid chromatography are reported. The procedures are simple, rapid (no special preliminary treatment is required), and accurate. There is no interference from other ingredients of the lotion (bentonite magma, calamine, and zinc oxide) or solution (acetone and boric acid).

A spectrophotometric determination of piperazine and some of its salts is described. The method depends on the UV measurement of the N-nitroso derivatives formed by the interaction of piperazine with nitrous acid. The chromophore is developed by heating the reaction mixture at 80 degrees C for 15 min, at pH 2.3--2.6. Beer's law is obeyed in the range 1--15 micrograms/mL.