Stability study of lipoic acid in the presence of vitamins A and E in o/w emulsions for cosmetic application.

The effectiveness of any cosmetic product containing a functional ingredient is determined by the skin delivery of the active molecule, which is influenced by the type of carrier and the molecule itself. Furthermore, the functional ingredient should be stable in the formulation. The purpose of this paper is to study the stability of lipoic acid in the presence of vitamins A (as palmitate) and E (as acetate) in semisolids for cosmetic use. The systems formulated were studied in regard to their aspect, pH, stability under centrifugation, and rheological behavior. The chemical analyses of lipoic acid and vitamins A and E were carried out by HPLC after studying the specificity of the method employed in each case. The quantitation of the active principles was performed by HPLC with C18 (5 microm) columns. The mobile phase was methanol for the vitamins, with spectrophotometric detection at 325 nm for vitamin A and 230 nm for vitamin E. The mobile phase for lipoic acid was methanol:water (80:20) and phosphoric acid at pH 3.0, with spectrophotometric detection at 332 nm. All systems were stable to centrifugation, and no significant modification of rheological behavior was observed in relation to the base emulsion used as control. The chemical studies performed indicated that although lipoic acid is not very stable in these formulations, the presence of vitamin A favors its chemical stability.

HPLC analysis of 5H-benzo[a]carbazole with antifungal activity.

A sensitive and simple high-performance liquid chromatographic (HPLC) method for the assay of 6,11-dihydro-2-methoxy-5H-benzo[a]carbazole (1) and 6,11-dihydro-2-methoxy-11-[2-(1-piperidinyl)]ethyl-5H-benzo[a]carbazole (2) was developed. The procedure is based on the use of the reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV detector. Each analysis required no longer than 11 min. A linear relationship between the concentration of both the drugs and the UV absorbance at 254 nm was obtained. This linearity was maintained over the concentration ranged from 5 to 80 microg/ml. The detection limits were found to be 1.6 and 0.7 ng for compounds 1 and 2. The quantitation limits were found to be 5.3 and 2.5 ng for compounds 1 and 2, respectively. For recovery studies, several determinations were carried out. Recovery values ranged from 98 to 102.1% for compound 1 and from 98.4 to 101.6% for compound 2. Method precision was also evaluated and RSD% found was less than 2%. This method was applied without any interference from degradation products.

Dissolution test for silymarin tablets and capsules.

Silybine (SBN), isosilybine (ISBN), silycristine (SCN), silydianine (SDN), and taxifoline (TXF) are the main active flavonoids commonly found in the dried fruits of Silybum marianum, Gaertner (Compositae). Concentrations of these compounds, except TXF, are usually expressed together as silymarin content. This paper describes a simple dissolution test developed to estimate silymarin (Sl) in pharmaceutical formulations. Five commercial products were tested using this new method (including tablets, sugar tablets, and capsules): two from Argentina, one from Brazil, one from Spain, and one from Italy. Results demonstrated that, provided the dosage form disintegrates, amounts dissolved range from 50 to 90% of the labeled value. Products were analyzed by high performance liquid chromatography (HPLC) and UV spectrophotometry.

Antitumoral activity of trisubstituted dihydrobenzo(a)carbazoles. Part III.

Two recently synthesized, trisubstituted dihydrobenzo(a)carbazoles were investigated regarding their anti-HIV and antitumoral activity. The compounds showed some activity against melanoma, renal cancer and breast cancer cell lines.

A stability-indicating HPLC method to determine cyproterone acetate in tablet formulations.

A simple and accurate liquid chromatographic method was developed to estimate cyproterone acetate (CA) in pharmaceuticals. The drug was chromatographed on a reversed-phase C18 column. Eluents were monitored at a wavelength of 254 nm utilizing a mixture (60:40) of acetonitrile and water. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for linearity, accuracy, precision, and selectivity. Due to its simplicity and accuracy, we believe that the method can be used for routine quality control analysis. No specific sample preparation is required except for the use of a column guard and a suitable prefilter attached to the syringe.

A new method for quality control of zinc pyritione pharmaceutical and cosmetic forms.

A simple high-performance liquid chromatographic (HPLC) method was developed to determine zinc pyritione in pharmaceutical and cosmetic products. Reversed-phase chromatography was conducted using a C18 column with an isocratic mobile phase consisting of a suitable mixture of methanol, acetonitrile, and water (30:2.5:20). The effluent was monitored on a ultraviolet (UV) detector at 243 nm. The method was validated following International Conference on Harmonisation (ICH) suggestions and proved accurate, precise, and specific.

Development and validation of a reversed-phase liquid chromatographic method for analysis of estradiol valerate and medroxyprogesterone acetate in a tablet formulation.

A simple and accurate liquid chromatographic method was developed for estimation of estradiol valerate and medroxyprogesterone acetate in pharmaceuticals. Drugs were chromatographed on a reverse phase C18 column, using a mixture (30:70) of ammonium nitrate buffer and acetonitrile and eluants monitored at a wavelength of 280 nm. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for its linearity, accuracy, precision and selectivity. Due to its simplicity and accuracy, the authors believe that the method may be used for routine quality control analysis. It does not require any specific sample preparation except the use of a column guard before the analytical column and suitable prefilter attached to the syringe prior to injection.

Bioavailability study of paracetamol tablets in saliva and urine.

A bioavailability study of two lots of paracetamol tablets was carried out in 5 healthy volunteers, using a crossover aleatory design, and drug monitoring in urine and saliva by high performance liquid chromatography (HPLC). Results were correlated with those obtained in an in vitro dissolution study. Statistical evaluation of bioavailability parameters indicates that the two formulations may be considered bioequivalent, in spite of differences found during early stages of the absorption process, which were preventable according to an in vitro dissolution study.

Antimicrobial activity of 5,6-dihydrobenzo-[a]-carbazoles. Part II.

A new series of twenty-two 5,6-dihydrobenzo[a]carbazoles was synthesized, some showing good antibacterial activity. The presence and position of substituents seems to be critical for such activity.

Effect of manufacturing technology on the dissolution of ampicillin tablets.

The effect of the manufacturing technology on the dissolution of ampicillin tablets have been analyzed. Several kinetic parameters were then calculated. The dissolution rate of ampicillin increases in tablets prepared by direct compression or dry granulation, with microcrystalline cellulose and colloidal silicon dioxide. Studies of in vitro bioequivalence of the pharmaceutical products available in the Argentine market were performed. We concluded that not all commercial products are equivalent.

Antimicrobial activity of 5,6-dihydrobenzo-[a]-carbazoles.

A new series of 5,6-dihydrobenzo[a]carbazoles was synthesized, some showing good antibacterial activity. The presence of a dialkylamino ethyl chain on the 2-, 3- or 4-O-substituent seems to be critical for such activity.

Synthesis of disubstituted tetrahydrocarbazoles with potential antidepressive activity.

A new series of disubstituted tetrahydrocarbazoles were synthesized. They are tested for antidepressive activity by the Porsolt's forced swimming test (one of the acute stress methods) and by the prevention of reserpine induced hypothermia and ptosis in mice. 3-Morpholino-1-[N-(6-methoxy-1,2,3,4- tetrahydrocarbozolyl)2-propanol, fumarate (XI) was demonstrated to be the most promising compound of this series. Besides, this series did not present the most common adverse effects of the conventional tricyclic-antidepressants (loss of locomotor coordination, ataxia and anticholinergic activity).

Conformational analysis of optically active phenylethylamines and phenylimidazolines.

Conformational and structural features of phenethylamine and phenylimidazoline derivatives with alpha-adrenergic activity have been studied by MNDO and PCILO methods. From the calculated conformational energy maps, we conclude that phenethylamines exhibit an extended conformation, while the phenylimidazolines adopt a position intermediate between that of corresponding extended and folded conformations. We conclude that the phenethylamines interact with classical Easson-Stedman sites, while the phenylimidazolines interact with a different site. Both phenethylamines and phenylimidazolines show similar requirements for a cationic recognition site.

Sinthetic trypanocides: growth-inhibiting properties of new 1, 2, 3, 4 - tetrahydrocarbazoles on Trypanosoma cruzi

Se sintetizaron varios nuevos derivados del 1,2,3,4, tetrahidrocarbazol, 5,6-dihidrobenzo (alfa) carbazol, 3-metilindol y benzimidazol, que se ensayaron sobre cultivos del Trypanosoma cruzi, en el medio líquido de Warren. El 6-cloro-y el 6,8 dicloro-N-(1-etil-N-dimetilamino) 1,2,3,4, tetrahidrocarbazol fumarato resultaron los más potentes inhibidores del crecimiento del parásito. Estos carbazoles fueron relativamente más activos que los preparados previamente por Poliakoff y col

Sinthetic trypanocides: growth-inhibiting properties of new 1, 2, 3, 4 - tetrahydrocarbazoles on Trypanosoma cruzi

Se sintetizaron varios nuevos derivados del 1,2,3,4, tetrahidrocarbazol, 5,6-dihidrobenzo (alfa) carbazol, 3-metilindol y benzimidazol, que se ensayaron sobre cultivos del Trypanosoma cruzi, en el medio líquido de Warren. El 6-cloro-y el 6,8 dicloro-N-(1-etil-N-dimetilamino) 1,2,3,4, tetrahidrocarbazol fumarato resultaron los más potentes inhibidores del crecimiento del parásito. Estos carbazoles fueron relativamente más activos que los preparados previamente por Poliakoff y col (AU)

Synthetic trypanocides: growth-inhibiting properties of new 1,2,3,4-tetrahydrocarbazoles on Trypanosoma cruzi.

Several new 1,2,3,4-tetrahydrocarbazole, 5,6-dihydrobenzo(alpha) carbazole, 3-methylindole and substituted benzimidazolyl compounds were synthesized and assayed for their action on growth of Trypanosoma cruzi, cultured in Warren's liquid medium. 6-chloro and 6,8-dichloro-N-(1-ethyl-N-diethylamino)-1,2,3,4-tetrahydrocarbazole++ fumarate resulted the more active in inhibiting growth of the parasite. The new compounds were apparently more effective than those prepared previously by Poliakoff et al. (5).

Synthetic trypanocides: growth-inhibiting properties of new 1,2,3,4-tetrahydrocarbazoles on Trypanosoma cruzi.

Several new 1,2,3,4-tetrahydrocarbazole, 5,6-dihydrobenzo(alpha) carbazole, 3-methylindole and substituted benzimidazolyl compounds were synthesized and assayed for their action on growth of Trypanosoma cruzi, cultured in Warrens liquid medium. 6-chloro and 6,8-dichloro-N-(1-ethyl-N-diethylamino)-1,2,3,4-tetrahydrocarbazole++ fumarate resulted the more active in inhibiting growth of the parasite. The new compounds were apparently more effective than those prepared previously by Poliakoff et al. (5).

NMR determination of isosorbide dinitrate and beta-adrenergic blocking agents in tablets.

An NMR spectroscopic method for the determination of isosorbide dinitrate, alone or together with alprenolol or propranolol, is described. Spectra are determined in dimethyl sulfoxide-d6 containing maleic acid or 1,4-dinitrobenzene as internal standards. Both synthetic mixtures and commercial formulations were assayed, and the results were compared using compendial procedures.