Liquid chromatographic determination of flunarizine dihydrochloride in the presence of its degradation product.

A simple, stability-indicating liquid chromatographic method has been developed for the assay of flunarizine dihydrochloride in the presence of its acid-induced degradation product. A Bondapak-C18 column was used with a mobile phase consisting of methanol-water (75:25, v/v) containing 0.5% w/v sodium chloride and 0.2% v/v triethanolamine adjusted to pH 6.6 with 30% hydrochloric acid at a flow rate 2 ml min-1. Quantitation was achieved with UV detection at 254 nm based on peak area or peak height ratios. The proposed method was successfully applied to the determination of the drug in laboratory-prepared mixtures in the presence of its degradation product and in capsules. Moreover, the method was utilized to investigate the kinetics of the degradation process at different temperatures and the apparent first-order rate constant, half-life and activation energy calculated.

Spectrophotometric determination of flunarizine dihydrochloride through the formation of charge-transfer complex with iodine.

A spectrophotometric method is described for the assay of flunarizine dihydrochloride. The method is based on the molecular interaction between the drug and iodine, to form a charge-transfer complex in which the drug acts as n-donor and iodine as sigma-acceptor. The iodine was found to form charge-transfer complex in a 1:1 stoichiometry with absorption bands at 295 and 355 nm. The concentrations were linear over 8-13 micrograms ml-1 at both 295 and 355 nm, respectively. A complete, detailed investigation of the formed complex was made with respect to its composition, associated constant and free energy change. The method has been applied successfully to the analysis of commercially available flunarizine dihydrochloride capsules without interference from the capsules excipient. To validate the proposed method, its accuracy and precision, the results were statistically compared with a newly developed reversed-phase HPLC procedure using Student-t and F-ratio tests.

Spectrophotometric analysis of some guanidino drugs by acid-dye and charge-transfer complexation methods.

Two spectrophotometric methods are described for the determination of guanethidine sulphate (I), guanfacine hydrochloride (II), guanoclor sulphate (III), guanoxan sulphate (IV) and debrisoquine sulphate (V). The first method involves ion-pair formation of the selected compounds (I-V) with bromocresol purple at pH 3.8. The yellow ion pair is extracted with chloroform and the absorbance is measured at about 415 nm. The second method is based on the reaction of the basic guanidino compounds (I, III-V) with iodine in chloroform to give molecular charge-transfer complexes with maximum absorbance at 292 and 345 nm. Beer's law was obeyed for both methods and the relative standard deviations were found to be less than 2%. The apparent molar absorptivities were found to be 2.1 x 10(4) to 6.9 x 10(4) l mol-1 cm-1 using bromocresol purple and 0.7 x 10(4) to 2.4 x 10(4) l mol-1 cm-1 using iodine. The investigated drugs were assayed in tablets. The mean percentage recoveries were found to be 99.8-100.8% by the acid-dye method and around 100.4% by the charge-transfer complexation method.

Spectrofluorimetric determination of guanethidine sulphate, guanoxan sulphate and amiloride hydrochloride in tablets and in biological fluids using 9,10-phenanthraquinone.

A highly sensitive spectrofluorimetric method for the determination of some drugs of the monosubstituted guanidine derivatives in laboratory made tablets, in spiked human serum and in urine samples is presented. The method is based on the reaction of guanethidine sulphate (I), guanoxan sulphate (II) and amiloride hydrochloride (III) with 9,10-phenanthraquinone (IV) to give highly fluorescent derivatives. The linearity ranges were found to be 0.06-0.96 mug/ml for (I) and (II) and 0.04-0.28 mug/ml for (III), with relative standard deviation less than 2%. Mean percentage recoveries for tablets were found to be 99.9 +/- 1.3, 100.5 +/- 1.1 and 100.0 +/- 1.6 for I, II and III, respectively. For I and III the results are highly correlated with the B.P. methods. Using the synchronous fluorimetry, differentiation between I and II was possible. Chloroform, dichloromethane and ethyl acetate have been used to extract I, II and III, respectively from serum and urine at basic pH, followed by applying the proposed fluorimetric method. Percentage recoveries were found to be 95.7-102.2%. The limit of detection is 0.04 mug/ml for I and II and 0.02 mug/ml for III.

Spectrophotometric determination of benzene in ethanol.

A rapid, simple spectrophotometric method for the detection and determination of benzene in ethanol is described. Thus, using 1 cm cuvettes and applying the first and/or the second derivative methods, benzene can be determined in ethanol over the concentration range of 5-25 p.p.m. with a CV% less than 1% and with a detection limit of 2 p.p.m. This is considered to be an improvement over the method currently given in the British Pharmacopoeia.

Susceptibility of Nubian goats to mercury poisoning in the Sudan.

Twelve Nubian goats were given single or repeated oral dosages of mercuric chloride at 10, 20 and 40 mg/kg and died or were killed in extremis at various times after dosing (18 hours-18 days). The main signs of poisoning were anorexia, frothing at the mouth, respiratory distress, epistaxis, bloat, diarrhoea, abnormal posture and recumbency. An increase in the activity of GOT and in the concentrations of urea and inorganic phosphate and a decrease in total protein and calcium concentrations in the serum were detected. The main lesions were dilatation and necrosis of the proximal convoluted tubules, shrinkage and disappearance of the glomerular tufts, varying amounts of acidophilic homogenous material in the lumens of the affected tubules of the kidney, enteritis, hepatocellular degeneration and/or necrosis and pulmonary congestion, haemorrhage, oedema and emphysema. The changes in the red blood cells indicated anaemia.

Experimental selenium poisoning in Nubian goats.

The toxicity of sodium selenite was studied in 28 Nubian goats, 20 of which died or were killed in extremis 2 h to 21 d after dosing. Single or repeated daily oral doses of 160, 80, 40, 20 and 5 mg sodium selenite/kg were toxic to goats while daily doses of selenite ranging from 0.25 to 1 mg/kg/d for 225 d were not toxic to this species of animals. The main signs of poisoning were uneasiness, inappetence, dyspnea, salivation, diarhea, paresis of the hind limbs, arching of the back, and recumbency. The main lesions were hemorrhages in the rumen, reticulum, osmasum and abomasum, hemorrhagic or catarrhal abomasitis and enteritis, fatty change and necrosis of the centrilobular hepatocytes and of the cells of the renal convoluted tubules, splenic hemosiderosis, pulmonary congestion, haemorrhage, edema and emphysema, accumulation of lymphocytes in the vital organs, and straw-colored fluid in the serous cavities.

First-derivative spectrophotometric determination of salicylic acid in aspirin.

Salicyclic acid has been determined in aspirin powder and tablets by first-derivative spectrophotometry at 316 nm with base-line correction, with a coefficient of variation less than 1%.

Spectrophotometric determination of vitamin A in oily capsules using first derivative curves.

The first derivative curve (D1) of the absorption spectrum of vitamin A acetate in cyclohexane possesses a trough (D11) at 348 nm and a maximum (D12) at 306 nm. D11, D12, and delta D1 (= D11 - D12) are linearly related to concentration over a range of 5-25 i.u. ml-1. When a tangent is drawn between D1 at 400 nm and D1, at 306 nm, the amplitude at 348 nm (D1 corr.) is linearly related to concentration. Ratios of magnitude of D11/magnitude of D12 and D1(corr.)/magnitude of D1 are independent of concentration, and have been used to reveal the presence of interferences in the D1 curves of vitamin A in oily capsules. Vitamin A in two oily preparations has been assayed using delta D1 and D1(corr.). The potency found was within +/- 2% from that obtained by using the B.P. method. The method is rapid, precise and accurate.

First derivative spectrophotometric determination of anhydrotetracyclines in tetracyclines.

A rapid method is presented for detection and determination of anhydrotetracycline-HCl (ATC-HCl) and 4-epianhydrotetracycline-HCl (4-EATC-HCl) in tetracycline-HCl (TC-HCl). The method determines the 2 compounds as a sum, not individually. The first derivative absorption curve has a trough (D1) at 460 nm which is linearly related to concentration (1-10 mg/mL). ATC-HCl + 4-EATC-HCl content was determined in TC-HCl powder and capsules by the D1 and the compensation D1 spectrophotometric methods. The results were compared with those obtained using U.S. Pharmacopeia and British Pharmacopoeia methods.

Clinical zinc and copper deficiencies in cattle of western Sudan.

Clinical cases of both Zn and Cu deficiencies are reported in a cattle farm in Kordofan Region of the Sudan after drought. The animals showed general weakness, stunted growth, infertility, parakeratosis and achromotrichia. There was macrocytic hypochromic anaemia and low Cu and Zn concentrations in sera. The condition was more prevalent in zebu-Friesian crosses than the local breeds. Drought and marginal or low Cu and Zn content in pasture may be the predisposing factors.

Determination of aztreonam and L-arginine combination in parenteral formulations.

A rapid, sensitive and precise liquid chromatographic method is presented for the determination of aztreonam alone, in the presence of its degradation product, and in a parenteral formulation containing l-arginine. A reverse phase column and 0.2M phosphate buffer (pH 6)-methanol (95 + 5) with mobile phase at a flow rate of 2 mL/min is used. The method is sensitive for the range of 10-50 micrograms/mL with a relative standard deviation of less than 2%. The method has been applied to a parenteral formulation containing aztreonam and l-arginine. L-Arginine is also determined by a nonaqueous titrimetric method.

Liquid chromatographic determination of cinnamic and benzoic acids in benzoin preparations.

A liquid chromatographic method for the individual determination of benzoic and cinnamic acids in 2 benzoin preparations is presented. The method specifies a reverse phase column and 0.01M KH2PO4-methanol (85 + 15) as mobile phase at a flow rate of 1.8 mL/min, with detection at 254 nm. The method has been applied to 2 benzoin preparations and the results were compared with those from the British Pharmacopoeia method.

Spectrophotometric and fluorimetric determination of nomifensine maleate.

Three methods have been developed for the determination of nomifensine maleate alone and in capsules: a spectrophotometric, an iodine charge-transfer, and a spectrofluorimetric method. All three give linear calibration graphs, over the ranges 20-100, 1-5 and 0.1-0.5 microg/ml, respectively, with coefficients of variation of 0.8, 1.3 and 1.3%, respectively.

Colorimetric determination of piperazine with p-benzoquinone.

Piperazine and its salts are reacted with aqueous alcoholic p-benzoquinone, buffered at pH 5.4, to give a coloured product with maximum absorption at 516nm. The piperazine base has a molar absorptivity of 0.96 x 10(4)l.mole(-1).cm(-1) and Beer's law is obeyed over the range 2-10 mug ml . When applied to three commercial preparations, the proposed method gave mean recoveries within 1% of those obtained by the official gravimetric method. The relative standard deviation was less than 1%.