Sensitive spectrophotometric determination of lamotrigine in bulk drug and pharmaceutical formulations using bromocresol green

Two new, simple, rapid and reproducible spectrophotometric methods have been developed for the determination of lamotrigine (LMT) both in pure form and in its tablets. The first method (method A) is based on the formation of a colored ion-pair complex (1:1 drug/dye) of LMT with bromocresol green (BCG) at pH 5.02±0.01 and extraction of the complex into dichloromethane followed by the measurement of the yellow ion-pair complex at 410 nm. In the second (method B), the drug-dye ion-pair complex was dissolved in ethanolic potassium hydroxide and the resulting base form of the dye was measured at 620 nm. Beer's law was obeyed in the concentration range of 1.5-15 µg mL-1 and 0.5-5.0 µg mL-1 for method A and method B, respectively, and the corresponding molar absorptivity values are 1.6932 x 10(4) and 3.748 x 10(4) L mol-1cm-1. The Sandell sensitivity values are 0.0151 and 0.0068 µg cm-2 for method A and method B, respectively. The stoichiometry of the ion-pair complex formed between the dug and dye (1:1) was determined by Job's continuous variations method and the stability constant of the complex was also calculated. The proposed methods were applied successfully for the determination of drug in commercial tablets.

Titrimetric assay of lisinopril in aqueous and non-aqueous media

Four simple titrimetric procedures are described for the determination of lisinopril (LNP) in bulk and in pharmaceuticals based on the neutralization of basic-amino and acidic carboxylic acid groups present in LNP. Method A is based on the neutralization of basic amino groups using perchloric acid as titrant in anhydrous acetic acid medium. Method B, method C and method D are based on neutralization of carboxylic acid group using NaOH, sodium methoxide and methanolic KOH, as titrants, respectively. Method A is applicable over 2.0-20.0 mg range and the calculations are based in the molar ratio of 1:2 (LNP:HClO4). Method B, method C and method D are applicable over 2.0-20.0 mg, 1.0-10.0 mg and 5.0-15.0 mg range, respectively, and their respective molar ratios are 1:1 (LNP:NaOH), 1:2 (LNP:CH3ONa) and 1:1 (LNP:KOH). Intraday and inter day accuracy and precision of the methods were evaluated and the results showed intra- and inter-day precision less than 2.7% (RSD), and accuracy of < 2.5 % (RE). The developed methods were applied to determine LNP in tablets and the results were validated statistically by comparing the results with those of the reference method by applying the Student's t-test and F-test. The accuracy was further ascertained by recovery studies via standard addition technique. No interferences from common tablet exipients was observed.

Development and validation of spectroscopic methods for simultaneous estimation and dissolution of ofloxacin and ornidazole in tablet dosage forms

The aim of this work was to develop and validate simple, accurate and precise spectroscopic methods (multicomponent, dual wavelength and simultaneous equations) for the simultaneous estimation and dissolution testing of ofloxacin and ornidazole tablet dosage forms. The medium of dissolution used was 900 ml of 0.01N HCl, using a paddle apparatus at a stirring rate of 50 rpm. The drug release was evaluated by developed and validated spectroscopic methods. Ofloxacin and ornidazole showed 293.4 and 319.6nm as λmax in 0.01N HCl. The methods were validated to meet requirements for a global regulatory filing. The validation included linearity, precision and accuracy. In addition, recovery studies and dissolution studies of three different tablets were compared and the results obtained show no significant difference among products.

Preliminary data on the prevalence of psychiatric disorders in Brazilian male and female juvenile delinquents

The aim of the present investigation was to study the prevalence of psychiatric disorders in a sample of delinquent adolescents of both genders and to compare the prevalence between genders. A total of 116 adolescents (99 males and 17 females) aged 12 to 19 on parole in the State of Rio de Janeiro were interviewed using the screening interview based on the Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime (KSADS-PL). Data were collected between May 2002 and January 2003. Of 373 male and 58 female adolescents present in May 2002 in the largest institution that gives assistance to adolescents on parole in the city of Rio de Janeiro, 119 subjects were assessed (three of them refused to participate). Their average age was 16.5 years with no difference between genders. The screening interview was positive for psychopathology for most of the sample, with the frequencies of the suggested more prevalent psychiatric disorders being 54% for attention-deficit/hyperactivity disorder, 77% for conduct disorder, 41% for oppositional defiant disorder, 57% for anxiety disorder 57, 60% for depressive disorder 60, 63% for illicit drug abuse, and 58% for regular alcohol use. Internalizing disorders (depressive disorders, anxiety disorders and phobias) were more prevalent in the female subsample. There was no significant difference in the prevalence of illicit drug abuse between genders. There were more male than female adolescents on parole and failure to comply with the sentence was significantly more frequent in females. The high prevalence of psychopathology suggested by this study indicates the need for psychiatric treatment as part of the prevention of juvenile delinquency or as part of the sentence. However, treatment had never been available for 93% of the sample in this study.

Effect of sildenafil citrate on the cardiovascular system

Sildenafil citrate is a drug commonly used to manage erectile dysfunction. It is designated chemically as 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H -pyrazolo[4,3-d]pyrimidin-5-yl)-4 ethoxyphenyl] sulfonyl]-4-methylpiperazine citrate (C22H30N6O4 S). It is a highly selective inhibitor of cyclic guanine monophosphate-specific phosphodiesterase type 5. In late March through mid-November 1998, the US Food and Drug Administration (FDA) published a report on 130 confirmed deaths among men (mean age, 64 years) who received prescriptions for sildenafil citrate, a period during which >6 million outpatient prescriptions (representing about 50 million tablets) were dispensed. The US FDA recently reported that significant cardiovascular events, including sudden cardiac death, have occurred in men with erectile dysfunction who were taking sildenafil citrate. These reports have raised concerns that sildenafil citrate may increase the risk of cardiovascular events, particularly fatal arrhythmias, in patients with cardiovascular disease. In the past few years, the cardiac electrophysiological effects of sildenafil citrate have been investigated extensively in both animal and clinical studies. According to extensive data available to date, sildenafil citrate has been shown to pose minimal cardiovascular risks to healthy people taking this drug. Some precautions are needed for patients with cardiovascular diseases. However, the only absolute contraindication for sildenafil citrate is the concurrent use of nitrates. This article is intended to review sildenafil citrate's cardiovascular effects, as well as current debates about its arrhythmogenic effects.

Physicochemical study of CaCO3 from egg shells

Calcium carbonate, a pharmaceutical excipient, is widely used as diluent in solid dosage forms. It is also used as a base for medicinal and dental preparations, a buffering and dissolution aid for dispersible tablets, a food additive and a calcium supplement. Egg shells are a rich source of mineral salts, mainly calcium carbonate, which corresponds to about 94% of the shell. Layer farms produce large amounts of shells, whose final disposal poses a challenge from the environmental standpoint. This work was designed to evaluate the physicochemical and thermal properties of calcium carbonate obtained from egg shells. The findings indicated that calcium carbonate from egg shells can be used as an alternative pharmaceutical excipient.

Development of effervescent products, in powder and tablet form, supplemented with probiotics Lactobacillus acidophilus and Saccharomyces boulardii

Probiotics are living microorganisms, which when administered in adequate amounts confer health benefits on the host through a beneficial influence on the intestinal microbiota related to competition and to antagonistic and immunological effects. Thus, the objective of this study was the development of effervescent products (tablets and powder) supplemented with the probiotics Lactobacillus acidophilus and Saccharomyces boulardii, and the identification of the best formulation in terms of viability of these microorganisms. The physical properties of the tablets (compressive force applied, mean weight, hardness, and friability) were assessed, and the viability of the microorganisms in the gastrointestinal tract and their stability during storage were also determined. The results show that the microorganisms remained stable and viable during the 60-day storage period in the effervescent powder. However, the results indicated that the effect of compression force affected the viability of the microorganisms during the production of the effervescent tablets.