Voltammetric study of salbutamol and application to its determination in a tablet dosage form and dissolution profiles for the dosage form

Development and validation of simultaneous spectrophotometric and TLC-spectrodensitometric methods for determination of beclomethasone dipropionate and salbutamol in combined dosage form

Spectrophotometric and TLC-spectrodensitometric methods were developed and validated for the simultaneous determination of beclomethasone dipropionate (BEC) and salbutamol (SAL). The spectrophotometric methods include dual wavelength, ratio difference, constant center coupled with a novel method namely, spectrum subtraction and mean centering with mean percentage recoveries and RSD 99.72±1.07 and 99.70±1.12, 100.25±1.12 and 99.89±1.12, 99.66±1.85 and 99.19±1.32, 100.74±1.26 and 101.06±0.90 for BEC and SAL respectively. The TLC-spectrodensitometric method was based on separation of both drugs on TLC aluminum plates of silica gel 60 F254, using benzene: methanol: triethylamine (10:1.5:0.5 v/v/v) as a mobile phase, followed by densitometric measurements of their bands at 230 nm. The mean percentage recoveries and RSD were 99.07±1.25 and 101.35±1.50 for BEC and SAL respectively. The proposed methods were validated according to ICH guidelines and were applied for the simultaneous analysis of the cited drugs in synthetic mixtures and pharmaceutical preparation. The methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of BEC and SAL in their pharmaceutical formulation with no need for prior separation. The results obtained were statistically compared to each other and to that of the reported HPLC method. The statistical comparison showed that there is no significant difference regarding both accuracy and precision.

Single-Walled-Carbon-Nanotube-Modified Pyrolytic Graphite Electrode Used as a Simple Sensor for the Determination of Salbutamol in Urine

A fast and sensitive voltammetric method has been proposed for the determination of salbutamol at single-walled-carbon-nanotube-modified edge-plane pyrolytic graphite electrode (SWNT/EPPGE) in human urine. The electrochemical response of salbutamol was determined by square wave voltammetry (SWV) in phosphate buffer solution (PBS) at physiological pH 7.2. The modified electrode showed improved voltammetric response towards the oxidation of salbutamol, and a well-defined anodic peak was observed at~600 mV with enhanced peak current in comparison to the bare electrode. Linear calibration plot using SWNT/EPPGE was obtained in the concentration range of 50 to 2500 ngml-1with sensitivity and detection limit of 2.15 nA/ngml-1and 4.31 ngml-1, respectively. The developed method has been successfully applied for the determination of salbutamol in commercial preparations and human body fluids. Fast analysis of salbutamol in human urine makes the proposed method of great interest for doping control purposes at the site of competitive games.

Electrochemical Oxidation of an Immunosuppressant, Mycophenolate Mofetil, and Its Assay in Pharmaceutical Formulations

Electrochemical oxidation of mycophenolate mofetil (MMF) has been studied at a glassy carbon electrode in aqueous solution over a wide pH range. MMF was oxidized on glassy carbon electrode (GCE) by an irreversible process that was controlled mainly by diffusion. The irreversibility of the electrode process was verified by different criteria. A probable mechanism for electrochemical oxidation of MMF was proposed. Differential-pulse voltammogram of the drug showed two oxidation peaks at 0.631 V and at 0.921 V (verses SCE) in phosphate buffer of pH 6.0. This process could be used to determine MMF in the concentration range of5.0×10−7to7.5×10−4 M with a limit of detection of1.48×10−7 M. The method was successfully applied for the analysis of MMF in pure and dosage forms and in biological fluids.

Sensitive detection of salbutamol using europium-enhanced fluorescence with trioctylphosphine oxide (TOPO) as coligand

In this work a simple and sensitive fluorimetric method for determination of salbutamol (4-[2-(tert-butylamino)-1-hydroxyethyl]-2-(hydroxymethyl) phenol) using an Eu enhanced signal was developed. The employed methodology is based on the formation of a ternary complex formed with Eu, salbutamol and trioctylphosphine oxide (TOPO). Intermolecular transfer of energy from the excited organic molecule to the lanthanide followed by lanthanide emission is responsible for excitation of the lanthanide ion in complex solutions and fluorescent enhancement. The luminescence properties of the ternary complex formed with TOPO and optimum formation conditions were investigated. The calibration curve is linear in the range between 6.92-180 microg l(-1) of salbutamol. The detection limit was 2.31 microg l(-1). Common excipients for these formulations were not found to interfere. A proposed method for the assay in commercial aerosols and nebulizer solutions containing salbutamol was applied with very good precision.

Determination of terbutaline based on oxidation by voltammetry

A voltammetric study of the oxidation of terbutaline has been carried out at an activated glassy carbon electrode. The compound was oxidized irreversibly at high positive potential. The response was evaluated with respect to pH, scan rate, nature of the buffer and other variables. The peak current, at about 0.8 V (versus a saturated calomel electrode), was proportional to the terbutaline concentration in the range of 8 x 10(-6)-8 x 10(-4) M in phosphate buffer pH 6.0. This method was applied, without any interferences from the excipients, to determine the drug in a tablet dosage form.

The effect of gamma radiation on the degradation of salbutamol

The use of ionizing radiation for sterilization of pharmaceuticals is now a well established technology. Degradation of salbutamol was investigated after gamma irradiation using HPLC and ESR spectroscopy. HPLC evidenced the formation of radiolytic products after gamma irradiation. Salbutamol showed a degradation of nearly 2% at 25 kGy. Sterilization of salbutamol in the liquid state appeared not technically feasible. Simulation of the increase of free radicals versus dose was performed using linear and polynomial regression. These radicals could be detected even after a storage period of more than 12 months.