No abstract

Ritodrine hydrochloride (RTH), chemically 1-(4hydroxy phenyl)-2-[2-(4-hydroxy phenyl) ethyl amino] propanol, is a potent tocolytic drug. Amoxicillin (AMX), 6-(p-hydroxy-α-aminophenyl acetamido) penicillanic acid, is the only phenolic penicillin, and it is used as an antibacterial drug. Many analytical procedures have been adopted for the determination of AMX, whereas very few methods have been used for RTH. The methods used for the determination of these drugs include titrimetry 1,2 , HPLC 3-7 , spectrophotometry for AMX 8-14 and for RTH. 15 Recently, 2-iodoxybenzoate was employed for the titrimetric determination of AMX. 16 Other methods, such as polarography 17,18 and fluorometry 19 , have been reported in the literature for the determination of AMX. The present paper describes the application of 3-methylbenzothiazolin-2one hydrazone (MBTH) for the determination of RTH and AMX in both pure and dosage forms. Reaction mechanism of the method Ritodrine and amoxicillin form a pink-colored product (λ max of 520 nm for RTH or 490 nm for AMX) with MBTH in the presence of ammonium cerium(IV) sulfate in acidic media. The absorption spectra of the colored products are given in Fig. 1. Under the reaction conditions, MBTH(I), upon oxidation with Ce(IV) ions, loses two electrons and one proton, forming an electrophilic intermediate(II), which is an active coupling species. 20,21 The intermediate of MBTH(II) undergoes electrophilic substitution with the phenolic moieties of RTH and AMX to form a colored product [III(a) and III(b)] according to Scheme 1. Experimental Apparatus Jasco (Model UVIDEC-610) and Elico (Model CL-27) spectrophotometers with 1 cm matched quartz cells were used for all absorbance measurements.

Acetyl acetone is introduced as a new coupling agent for the spectrophotometric determination of some chemotherapeutic agents, such as metoclopramide, dapsone, p-aminobenzoic acid, and cisapride in both pure and dosage forms. The method is based on the diazo-coupling reaction of these chemotherapeutic agents with a new coupling agent, acetyl acetone, in an alkaline medium. The optimum reaction conditions and other analytical parameters are evaluated. The influence of the substrates commonly employed as excipients with these chemotherapeutic agents has been studied. The method is simple, rapid, and sensitive. The results obtained compare favorably with those obtained with other reference methods.

No abstract

A simple, rapid, and accurate HPLC method is described for the determination of ritodrine hydrochloride (RTH) in both pure form and pharmaceutical formulations. A Hypersil Shendon ODS column with a mobile phase of dibasic phosphate buffer and acetonitrile (75 : 25) and isoxsuprine hydrochloride were used as an internal standard. The flow rate was 1 mL min -1 and the effluent was monitored at 270 nm pH 4.0. The calibration graph is linear in the range 2-30 µ g mL -1 . The proposed HPLC method has been successfully employed for the determination of RTH in Yutopar tablets and injection solutions.