Simultaneous determination of reserpine and hydrochlorothiazide in two-component tablet formulations by high-performance liquid chromatography

A high-performance liquid chromatographic procedure is presented for the simultaneous determination of reserpine and hydrochlorothiazide in two-component tablet formulations. An aliquot of a tetrahydrofuran extract of the tablet, containing polylythiazide as an internal standard, is chromatographed on a microparticulate silica gel column using a mobile phase of 0.01% (v/v) diethylamine, 5% (v/v) chloroform, and 18% (v/v) 2-propanol in n-hexane. The relative standard deviations are 1.2 and 0.6% for the simultaneous determination of reserpine and hydrochlorothiazide, respectively. Seven commericial tablet formulations were found to contain 92.7--101.0% and 98.3--101.4% of the labeled amounts of reserpine and hydrochlorothiazide, respectively.     

An in vivo rodent model of contraction-induced injury in the quadriceps muscle

Most animal studies of muscle contractile function utilise the anterior or posterior crural muscle (dorsiflexors and plantarflexors, respectively). An advantage to using these muscles is that the common fibular and tibial nerves are readily accessible, while the small size of the crural muscles is a disadvantage. Working with small muscles not only makes some in vivo imaging and the muscle testing techniques more challenging, but also provides limited amounts of tissue to study. The purpose of this study was to describe a new animal muscle injury model in the quadriceps that results in a significant and reproducible loss of force. The thigh of Sprague Dawley rats (N=5) and C57BL/10 mice (N=5) was immobilised and the ankle was attached to a custom-made lever arm. The femoral nerve was stimulated using subcutaneous electrodes and injury was induced using 50 lengthening ("eccentric") contractions through a 70° arc of knee motion. This protocol produces a significant and reproducible injury, with comparable susceptibility to injury in the rats and mice. This novel model shows that the quadriceps muscle provides a means to study whole muscle contractility, injury, and recovery in vivo. In addition to the usual benefits of an in vivo model, the larger size of the quadriceps facilitates in vivo imaging and provides a significant increase in the amount of tissue available for histology and biochemistry studies. A controlled muscle injury in the quadriceps also allows one to study a muscle, with mixed fibre types, which is extremely relevant to gait in humans and quadruped models.     

Nadolol: high-pressure liquid chromatographic methods for assay, racemate composition and related compounds.

High-pressure liquid chromatographic (HPLC) methods have been developed for the determination of drug content, racemate A and related compounds in nadolol raw materials. The method for drug content and related substances resolved seven related compounds and several unknown impurities from the drug. The minimum quantifiable levels were 0.05% or less for four of the seven related compounds and 0.3% or less for the remainder. Total impurities in eight raw material samples ranged from 0.06 to 0.96% and assay levels ranged from 98.7 to 101.0%. The method was adapted for the determination of nadolol racemate A by a change in mobile phase composition. One raw material sample contained less than 40% of racemate A. Two samples which had a granular appearance were variable in racemate A content. The methods were adapted for the determination of drug and racemate A in nadolol tablets. Drug content in three tablet samples was between 96.2 and 98.4% and racemate A content was about 52%.     

A monoclonal anti-pan-T-cell antibody. In vitro and in vivo studies

A murine monoclonal antihuman T cell antibody is described that is pan-T in that it reacts with all T cells, including those from thymus, but not with B cells or other cells, except for a small subpopulation of null cells. Biochemical analysis demonstrated that the antigen detected is a glycoprotein, Mr 50,000 daltons, in which sialic acid, alpha-fucose and alpha-mannose are the important terminal or subterminal carbohydrates. Further analysis indicated that the antigen is the E-rosette-forming-cell (ERFC) receptor or a closely associated structure. Three patients with renal allograft rejection were treated with the pan-T cell monoclonal antibody and, although the antibody was in excess and bound to circulating T cells, no lasting effect on T cell numbers or graft rejection was noted.     

Gas chromatographic method for solvent residues in drug raw materials

A gas chromatographic (GC) method for screening drug raw materials, soluble in aqueous media, for volatile solvent residues has been developed. After dissolution, separate portions of the drug are each separately extracted with n-octane, toluene, and ether and injected into a chromatograph equipped with a porous polymer column and a flame ionization detector. The range of extractant polarities provides chromatograms which, taken together, are free of interfering peaks from 0 to approximately 20 min. Peaks due to solvent residues in the drug are identified by retention time with confirmation of identity by GC-MS.