Hemavathi N. Deepakumari

Spectrophotometric Estimation of Flutamide in Pure and in Pharmaceutical Preparations

Three simple, rapid, precise, sensitive, and accurate visible spectrophotometric methods (A, B, and C) are described for the estimation of flutamide in both pure and pharmaceutical preparations. They are based on the diazotization of reduced flutamide (FA) with nitrous acid followed by coupling with acetyl acetone (method A), citrazinic acid (method B), and 8-hydroxyquinoline (method C) to form colored azo dyes, exhibiting absorption maxima at 410, 440 and 500 nm, for methods A, B, and C, respectively. Linear concentration range was of 0.5–12, 0.5–10, and 0.3–10 μg/mL for methods A, B, and C, respectively, and the corresponding molar absorptivity values are , , and  L mol−1 cm−1. The correlation coefficients for FA are 0.9988, 0.9976, and 0.9975 for methods A, B, and C, respectively. All variables were optimized, and the results were statistically compared with those of a literature method by employing Student’s t-test and F-test. No interference was observed from common adjuvants normally added to the tablets. The relative standard deviations () for FA in all the three methods in the tablets are always less than 3%.

Synthesis and Anticonvulsant Activity of N‐(Substituted)‐1‐methyl‐2,4‐dioxo‐1,2‐dihydroquinazoline‐3(4H)‐carboxamides

A series of new N‐(substituted)‐1‐methyl‐2,4‐dioxo‐1,2‐dihydroquinazoline‐3(4H)‐carboxamides were designed, synthesized, and evaluated for their anticonvulsant activity. Most of the synthesized compounds exhibited potent anticonvulsant activities in the maximal electroshock (MES) and pentylenetetrazol (PTZ) test. The most promising compound 4c showed significant anticonvulsant activity with a protective index value of 3.58. The compounds 4a–c were also found to have encouraging anticonvulsant activity in the MES and PTZ screen when compared with the standard drugs, valproate and methaqualone. The same compounds were found to exhibit advanced anticonvulsant activity as well as lower neurotoxicity than the reference drugs.

Development and Validation of a Stability Indicating RP-UPLC Method for Analysis of Imipramine Hydrochloride in Pharmaceuticals

The objective of the current study was the development of a simple, rapid, and accurate isocratic reverse-phase ultra-performance liquid chromatographic (RP-UPLC) method for the routine control analysis of imipramine hydrochloride (IMH) in bulk drug and in pharmaceutical formulations. This work was carried out in order to reduce analysis time and maintaining good efficiency which in turn is focused on high-speed chromatographic separations. The method was developed using Waters Acquity BEH C18 column (100 mm × 2.1 mm, 1.7 μm) with mobile phase consisting of a mixture of acetonitrile and ammonium acetate buffer of pH-5 (80 : 20, v/v/v). UV detection was performed at 220 nm for eluted compound. An excellent linearity was observed in the concentration range 0.2–3 µg/mL IMH with a regression coefficient () value of 0.9999. The method developed was validated and forced degradation was performed as per ICH guidelines. The limit of detection () was 0.2532 ng/mL and the limit of quantitation () was found to be 0.7672 ng/mL. The drug IMH was subjected to hydrolytic, acidic, basic, thermal, photolytic, and oxidative stress conditions according to ICH regulations. IMH was found to be stable in basic, thermal, and photolytic conditions and degrades in acidic, hydrolytic, and oxidative stress conditions.

A Sensitive Spectrophotometric Estimation of Nimodipine in Tablets and Injection Using Phloroglucinol

A rapid, simple, and sensitive spectrophotometric method has been described for the determination of nimodipine in bulk drug, tablets, and injection. The proposed method is based on the diazotization of reduced nimodipine with nitrous acid followed by coupling with phloroglucinol to form colored azo dye and showing absorption maximum () at 410 nm. The formed colored azo dye is stable for about more than 2 h. The method obeyed Beer’s law over the concentration range of 0–25 μg/mL and the corresponding molar absorptivity value is  L/moL/cm. The Sandell sensitivity values limits of detection (LOD) and quantification (LOQ) values have also been reported for the developed method. The accuracy and precision of the method was evaluated on intra- and interday basis; the relative error (%RE) and the relative standard deviation (RSD) were <2.0%. All variables have been optimized and the presented reaction sequence was applied to the analysis of nimodipine in bulk drug, tablets, and injections. The performance of this method was evaluated in terms of Student’s -test and variance ratio -test to find out the significance of proposed method over the reference method.

Spectrophotometric Estimation of Nitrazepam in Pure and in Pharmaceutical Preparations

Three simple, sensitive, accurate, and rapid visible spectrophotometric methods (A, B, and C) have been developed for the estimation of nitrazepam in both pure and in pharmaceutical preparations. They are based on the diazotization of reduced nitrazepam with nitrous acid followed by coupling with acetyl acetone (method A), diphenylamine (method B), and citrazinic acid (method C) to form colored azo-dyes, exhibiting absorption maxima () at 400, 550, and 460 nm, for methods A, B, and C, respectively. The produced colored azo-dyes are stable for more than 2 h. Beers law was obeyed in the concentration range of 0.5–20, 0.3–14 and 0.5–12 μg/mL for methods A, B, and C, respectively and the corresponding molar absorptivity values are , , and  L mol−1cm−1. All variables have been optimized and the results were statistically compared with those of a literature method by employing the Students t-test and F-test. No interference was observed from common adjuvants normally added to the tablets. The results obtained in the proposed methods are in good agreement with labeled amounts, when marketed pharmaceutical preparations are analyzed, which could be applied in the routine quality control analysis laboratory.

Use of the Charge Transfer Reactions for the Spectrophotometric Determination of Risperidone in Pure and in Dosage Forms

The aim of study was to develop and validate two simple, sensitive, and extraction-free spectrophotometric methods for the estimation of risperidone in both pure and pharmaceutical preparations. They are based on the charge transfer complexation reactions between risperidone (RSP) as n-electron donor and p-chloranilic acid (p-CA) in method A and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in method B as π-acceptors. In method A, RSP reacts with p-CA in methanol to produce a bright pink-colored chromogen measured at 530 nm whereas, in method B, RSP reacts with DDQ in dichloromethane to form orange-colored complex with a maximum absorption at 460 nm. Beers law was obeyed in the concentration range of 0–25 and 0–50 μg/mL with molar absorptivity of 1.29 × 104 and 0.48 × 104 L/moL/cm for RSP in methods A and B, respectively. The effects of variables such as reagents, time, and stability of the charge transfer complexes were investigated to optimize the procedures. The proposed methods have been successfully applied to the determination of RSP in pharmaceutical formulations. Results indicate that the methods are accurate, precise, and reproducible (relative standard deviation <2 %).