C. Vetuschi

Photodegradation monitoring of amlodipine by derivative spectrophotometry

A derivative spectrophotometric method for the simultaneous determination of amlodipine and its pyridine photodegradation product has been developed. The analytes concentrations were linearly correlated with spectral measurements in the 3rd order UV derivative spectrum through equations obtained by simple and multiple regression analysis. The recovery values were estimated to range from 95 to 99% and the quantitation limit of the photoproduct was found to be equivalent to an impurity level of 1%, with respect to the content of amlodipine. The method could usefully be applied to routine quality control of pharmaceutical formulations containing amlodipine.

Progesterone administration by nasal spray

The bioavailability and the clinical usefulness of the P administered by nasal spray were investigated. Ten healthy menopausal women received an IN spray administration (4 doses of an oleic P solution 20 mg/mL, corresponding to nearly 11.2 mg of P) and the circulating P levels were calculated. Sixty minutes after administration, the maximum concentration (CMax, 3.75 +/- 0.214 ng/mL) was reached. High P levels (greater than 2 ng/mL) lasted until 360 minutes, and the AUC 0 to 720 was 1,481.6 +/- 343 ng.h/mL. Progesterone administration by spray formulation has proven to be effective in reaching therapeutic levels and to be acceptable to patients and, probably, clinically safe.

Nasally-administered progesterone: comparison of ointment and spray formulations

The aim of the study was to compare the bioavailability and clinical usefulness of progesterone (P) administered nasally in spray or ointment form. Twenty healthy post-menopausal women were randomly allocated to treatment by either intranasal spray (4 doses of an oil-based P solution at a concentration of 2 mg/0.1 ml, corresponding to a total dose of approximately 11 mg of P) or an ointment (quantity 0.1 ml, P concentration 20 mg/0.1 ml). Circulating P levels were calculated at various time intervals following administration. The spray formulation yielded a mean maximum concentration (CMax) of 3.75 ng/ml after 60 min (TMax) and the area under the curve (AUC) 0-720 min was 1481.6 +/- 343 ng.h/ml. The ointment yielded a mean CMax of 1.19 ng/ml at TMax = 30 min, the AUC 0-720 value being 404.35 +/- 148 ng.h/ml. The study findings confirmed that the intranasal route is a potentially useful alternative for the administration of natural sex steroid hormones, making it possible to avoid first-pass liver metabolism. P administered by spray showed greater bioavailability than it did when administered in ointment form, while both formulations seemed to be acceptable to patients and were probably clinically safe.

Analysis of nimodipine and its photodegradation product by derivative spectrophotometry and gas chromatography

Abstract A derivative spectrophotometric method for the simultaneous determination of nimodipine and its major degradation product in commercial pharmaceutical forms is proposed. The method has been defined on synthetic mixtures and compared with a new gas chromatographic procedure, as a reference method. The UV method has been used to study drug photodegradation in commercial specialities. Both methods, whose results are statistically compared, show satisfactory values of accuracy and reproducibility.

Application of a classical least-squares regression method to the assay of 1,4-dihydropyridine antihypertensives and their photoproducts.

A multicomponent UV spectrophotometric method using a classical least-squares (CLS) algorithm has been developed for the quantitative determination of 1,4-dihydropyridine (DHP) calcium antagonists and respective photoproducts. The procedure was optimized by defining a fractionation scheme for selecting the more useful wavelength ranges to be used in the calibration model. The method is potentially able to be extended to the other drugs of the same family. The recovery values from synthetic mixtures and commercial formulations were verified to be 99.09 and 97.85% for drug parents and degradation products, respectively. The sensitivity for the photoproducts determination was found to be below 0.8%. The results obtained from laboratory mixtures and commercial formulations were compared with those provided by UV derivative spectrophotometry.

Gas chromatographic and UV derivative determination of nitrendipine and its photodegradation product

Abstract A rapid and direct analytical UV method, based on third derivative spectra, and a gas chromatographic assay, for the simultaneous determination of nitrendipine and its photodegradation product, are proposed. Both procedures, showing satisfactory values of accuracy and precision, can be employed to measure the drug and its impurity in pharmaceuticals.

Determination of p-aminosalicylic acid and m-aminophenol by derivative UV-spectrophotometry

A direct method for the simultaneous determination of p-aminosalicylic acid (PAS) and its major decomposition product, m-aminophenol (MAP), is described. The analysis is based on the use of derivative UV-spectrophotometry and is a rapid procedure which gives accurate and precise results. A simple purity test which utilizes the third derivative spectrum is also reported and compared with the USP XX spectrophotometric method for the estimation of MAP in PAS formulations.

Propofol assay in biological fluids in pregnant women

A rapid, accurate and sensitive UV derivative method was described for measuring the Propofol concentration in some biological fluids. Furthermore two alternative procedures, a gaschromatographic and a colorimetric, were also defined, and the results of the three methods, when applied on blood samples spiked with known amounts of analyte, were compared. The samples were preliminary purified by a solid phase extraction on octadecyl C18 cartridge. The UV derivative method was applied to a pharmacokinetic study on pregnant women undergoing cesarean sections. After an induction dose administration of 2.5 mg kg-1, the maternal and umbilical vein blood were found to have comparable concentrations of propofol, with a mean half like of about 3.5 min; on the contrary no detectable levels of the drug were found in amniotic fluid. The drug recoveries > 98% and the response was linear over the range 0.05-40 micrograms ml-1.

Fourth UV derivative spectrophotometry for the simultaneous assay of atenolol and chlorthahdone in pharmaceuticals

Abstract A rapid derivative spectrophotometric method for the simultaneous determination of atenolol and chlorthahdone. in antihypertensive specialities, is described. The analytical procedure is based on the linear relationship between the atenolol concentration and the minimum peak at 236 nm and that between the, chlorthalidone concentration and the two signals arising from the minimum peak at 236 nm and a peak-trough at 229−218 nm. Satisfactory values for the precision and accuracy of the method have been estimated.

Anti-beer Evaluation of Hydrochlorothiazide and Losartan by UV Derivative Spectrophotometry

Abstract An UV derivative method for the simultaneous determination of Hydrochlorothiazide (HCT) and Losartan (LST) in the commercial forms was developed. The fourth derivative spectrum from the alcoholic solution was used. HCT can be determined by a specific signal at 330–340 nm, while LST uses the signal around 280–290 nm, common to both products. Into the concentration range of HCT (10.8–500)10−3 mg mL−1 and of LST (20–2400)10−3 mg mL−1, for their mixture in the ratio 1:4, two intervals were identified, one for lower values, for which the absorbance grows with concentration, and one for higher values, in which the absorbance of the solution diminishes as concentration increases. The second behaviour seems to be due to intramolecular reactions of the drugs. For both the intervals, linear regressions were obtained by correlating the spectra signals with the drug concentrations. The best results were obtained by employing the regression equations from the downward section.