A new spectrophotometric method for the determination of methyldopa.

A new, simple and low cost spectrophotometric method for the determination of methyldopa in pharmaceutical preparations was developed. The method was based on the coupling of methyldopa with 2,6-dichloroquinone-4-chlorimide (DCQ). The absorbance maximum (λ max) of the resulted colored product was at 400 nm.

Spectrophotometric methods for the determination of cefprozil in bulk and dosage form.

Two simple spectrophotometric methods were developed for the determination of cefprozil in pure bulk and in tablets forms. The first is a colorimetric method based on the coupling of cefprozil, after being hydrolyzed by sodium hydroxide (0.1N), with ascorbic acid as a chromogen (method A).

Stability studies on some benzocycloheptane antihistaminic agents.

The photostability of selected benzocycloheptane antihistaminic agents, namely, loratadine (I), pizotifen (II), ketotifen fumarate (III) and cyproheptatidine (IV), was investigated. Both I and II were photolabile while III and IV were photostable. To perform stability studies on the photolabile compounds (I and II), specific stability-indicating high performance liquid chromatographic (HPLC) methods were established.

Stability studies on diloxanide furoate: effect of pH, temperature, gastric and intestinal fluids.

The degradation of the amoebicide diloxanide furoate in alkaline medium at different temperatures was investigated using both a spectrophotometric and a developed HPLC method. In solutions, the drug was found to undergo decomposition, i.e.

Effects of alkali and simulated gastric and intestinal fluids on danazol stability.

The degradation kinetics of methanolic solution of danazol (0.020% w/v) in aqueous buffers and sodium hydroxide was investigated using stability-indicating HPLC method. The drug degrades in alkaline medium through a base-catalysed proton abstraction rather than via an oxidative mechanism involving oxygen species.

Studies on the cardiovascular depressant effects of N-ethyl- and N-benzyl-1,2-diphenylethanolamines in the rat: elucidation of the mechanisms of action.

The influence and mechanisms of action of N-ethyl- and N-benzyl-1,2-diphenylethanolamines (compounds E and B, respectively) on the arterial blood pressure and the heart rate of the rat together with their effects on CaCl2-induced arrhythmias in the rat were investigated. Both E and B in doses of (1.5-12 micromol/kg IV) decreased the arterial blood pressure and the heart rate in a dose-dependent manner.

Studies on the spasmolytic and uterine relaxant actions of n -ethyl and n -benzyl-1,2-diphenyl ethanolamines: elucidation of the mechanisms of action.

The influence of N -ethyl- and N -benzyl-1,2-diphenyl ethanolamines (compounds E and B, respectively) was examined on the spontaneously contracting rabbit jejunum and the rat uterus together with their influence on the contractions induced by some spasmogens in the guinea-pig ileum and oxytocics and CaCl2in the pregnant rat uterus. Both E and B inhibited the spontaneous contractions of the rabbit jejunum with ID50values of 0.13 and 0.

Effect of pirenzepine on the N-demethylation of D(-)ephedrine and ethylmorphine by rabbit liver microsomes.

The possible interaction of pirenzepine with the mixed-function oxidases obtained from phenobarbital-pretreated rabbit microsomes was examined in vitro. Under experimental conditions that did not lead to its own N-demethylation, the drug inhibited the microsomal oxidase systems responsible for the N-demethylation of D(-)ephedrine and ethylmorphine. Kinetic studies showed that pirenzepine inhibited the metabolism of both drugs in a competitive manner.

Effects of N-methyl- and N-isobutyl-1,2-diphenyl ethanol amines on the spontaneous and evoked contractions in the rat isolated uterus.

1. The effects of N-methyl- and N-isobutyl-1,2-diphenyl ethanol amine (compounds M & E), respectively and diltiazem (D) were examined on the spontaneous and evoked uterine contractions of pregnant rats in vitro. 2.

Cardiovascular depressant effects of N-methyl- and N-isobutyl-1,2-diphenyl ethanolamines: elucidation of the mechanisms of action.

The cardiovascular effects of N-methyl-1,2-diphenyl ethanolamine (compound M) and N-isobutyl-1,2-diphenyl ethanolamine (compound E) were examined in anaesthetized rats and their effects were compared with those of verapamil and diltiazem. Administration of compound M (10-80 mumole/kg), compound E (2-16 mumole/kg), diltiazem (1.5-24 mumole/kg) or verapamil (1.

Synthesis and antinociceptive activity of ring substituted N-[(2-phenyl-2-hydroxy)ethyl]-4-phenyl-4-carboethoxypiperidines.

A series of phenyl substituted N-[(2-phenyl-2-hydroxy)ethyl]-4-phenyl-4-carboethoxylpiperidine were synthesized and their antinociceptive activity tested in mice and compared with morphine sulphate. All compounds demonstrated antinociceptive activity in both the hot plate and the writhing tests. The studies showed that the antinociceptive activity is dependable on both the nature and the position of the substituent on the phenyl ring.

Antiaggregatory activity of N-methyl- and N-isobutyl-1,2-diphenyl ethanolamines in rat platelets.

The ability of N-methyl-1,2-diphenyl ethanolamine (compound M), N-isobutyl-1,2-diphenyl ethanolamine (compound E), diltiazem and verapamil to inhibit in vitro ADP-induced platelet aggregation was examined in rat platelet-rich plasma. Pretreatment of the platelets with the compounds (0.1-3 mM) for 3 min at 37 degrees C, inhibited an ADP-induced aggregation in a concentration-dependent manner.

Antipsychotic properties of new N-(4-substituted-1-piperazinylethyl)- and N-(4-substituted-1-piperidinylethyl)-phthalimides.

A series of N-(4-phenyl- and 4-pyridyl-1-piperazinylethyl)- and N-(4-phenyl-1-piperidinylethyl)-phthalmides were synthesized and tested for antipsychotic activity. All compounds suppressed the spontaneous motor activity and the apomorphine-induced climbing in mice and pergolide-induced locomotor activity in rats, demonstrating psychotropic properties equal to the corresponding properties of sulpiride. Although the compounds, like sulpiride, were less potent than haloperidol in blocking the locomotor activities, they caused no catalepsy, a major side effect following treatment with conventional antipsychotic agents.

Synthesis and pharmacological activity of N-alkyl-1,2-diphenylethanolamines.

A series of N-alkyl-1,2-diphenylethanolamines were synthesized and their pharmacological activities evaluated on various mammalian organs and systems. All compounds produced a generalized inhibitory effect on smooth and cardiac muscles and an increase in coronary flow as well as a brief reduction in rabbit blood pressure. The latter effect was not prevented by pretreatment of the animals with atropine, propranolol, or metoprolol.

Synthesis and antimicrobial activity of new furan derivatives.

5-Nitrofuran derivatives were synthesized and their antibacterial activity was investigated using standard bacterial strains and clinical isolates. The compounds showed inhibitory effects on both Gram-positive and Gram-negative organisms.

Mechanistic, inhibitory and stereochemical studies on cytoplasmic and mitochondrial serine transhydorxymethylases.

By using cytoplasmic and mitochondrial serine transhydroxymethylase isoenzymes from rabbit liver, it was shown that both enzymes exhibited similar ratios of serine transhydroxymethylase/threonine aldolase activities. Both enzymes catalysed the removal of the pro-S hydrogen atom of glycine, which was greatly enhanced by the presence of tetrahydrofolate. The cytoplasmic as well as the mitochondrial enzyme catalysed the synthesis of serine from glycine and [3H2]formaldehyde in the absence of tetrahydrofolate.