Identification of hydrazone of norethindrone, a metabolic product resulting from the interaction between isoniazid and norethindrone

Co-administration of isonicotinic acid hydrazide (isoniazid, INH) and 17 alpha-ethinyl-17 beta-hydroxyestr-4-en-3-one (norethindrone, NE) resulted in the formation of the isonicotinyl hydrazone of norethindrone (INH-NE) in rat stomach. Rat liver metabolized the latter compound in vitro. The metabolic product was characterized, following its derivatization with p-methoxy-benzaldehyde (PMBA), by comparison of chromatographic and mass spectral properties with synthetic reference compound. Results showed that INH-NE was cleaved at the amide bond resulting in the formation of the hydrazone of norethindrone. The physicochemical characteristics of synthetic PMBA hydrazone of norethindrone are described.

A radio-immunological assay for triamcinolone in plasma

A specific radioimmunoassay for the determination of picogram quantities of triamcinolone in plasma is reported. A rapid chemical separation method was incorporated in the procedure to remove the interfering endogenous hydrocortisone which cross reacts (5%) with the antiserum. Application of this radioimmunoassay to the analysis of triamcinolone plasma concentrations following oral administration of a 5 mg dose of the drug to a human volunteer is described.

A specific radio-immunological assay for prednisolone in plasma

A new, specific radio-immunological assay (R.I.A.) for prednisolone in plasma is described. The R.I.A. incorporates a procedure whereby the endogenous interfering hydrocortisone (in de-proteinized plasma) reacts directly with Girard Reagent T, resulting in a derivative which does not cross react with the specific antibody for prednisolone. The assay is sensitive (quantitation levels are in the 5-10 ng/ml range). The specificity compares favorably with that of a high performance liquid chromatographic procedure.

Objective determinations of sensibility in the upper extremity. Part I. Median nerve sensory conduction velocities

Distal sensory conduction velocities were determined in 109 normal median nerves. A significant decrease in sensory conduction velocity was noted with increasing age. Latencies increased with age but this relationship was not significant in men. Variables which contribute to the wide range of normal conduction velocities are discussed, and the need for each clinician to establish his own testing procedure is stressed. An additional method for assessing sensory function is suggested.

Objective determinations of sensibility in the upper extremity. Part II. Application of cutaneous stimuli in control subjects

Sensitization statements were read to two groups of normal subjects to determine whether quantifiable thresholds for pressure, electrical, or tactile stimuli could be altered. Significant reductions in perception thresholds were observed for pressure and digital pulsed stimulation, but not for stimulation to the discomfort threshold, or two point discrimination. These data seem to suggest that increased sensitization is related to the ease of stimulus applications and the comparative simplicity of sensory processing.

Objective determinations of sensibility in the upper extremity. Part III. Application of cutaneous stimuli in patients with peripheral nerve lesions

Quantitative values for pressure, electrical, and two-point touch stimulation were examined in five patients with peripheral nerve injuries of the ulnar or median nerves. Analyses of profiles generated for each stimulus application in each patient participating in this preliminary study suggest that, following the reading of a sensitization statement, pressure and electrical shock threshold values are clearly reduced compared to similar measurements in the unaffected limb. Values obtained prior to the statement indicated progressively reduced thresholds, however. Changes in sensation appear to precede significant improvements in sensory nerve conduction velocity. Limitations in the sensory testing techniques as well as suggestions for improving its validity are discussed.

Quantitation of digoxigenin in serum following oral administration of digoxin in humans

Separation of the acid breakdown products from digoxin in serum was accomplished by high performance liquid chromatography (HPLC). The major, less cardioactive, product digoxigenin was quantitated by several different commercial antisera from digoxin radioimmunoassay (RIA) kits. When two normal subjects were given digoxigenin (0.5 mg) orally appreciable concentrations were detected by digoxin RIA kit. Administration of a digoxin (0.5 mg) solution to the same overnight-fasted recumbent volunteers resulted in digoxigenin detection (HPLC-RIA) in serum only in one subject.

Analysis of prednisolone in plasma by high-performance liquid chromatography

A sensitive, specific high-performance liquid chromatographic procedure for the determination of prednisolone in plasma is described. The organic solvent extract from plasma is chromatographed on a silica gel column using a mobile phase of 0.2% glacial acetic acid, 6% ethanol, 30% methylene chloride in n-hexane on a high-performance liquid chromatograph fitted with an ultraviolet dector (254 nm). Quantitation of plasma samples containing 25 ng/ml prednisolone is reported. Metabolites and endogenous hydrocortisone do not interfere with prednisolone. The determination of prednisolone concentration in plasma following administration of a 10-mg single oral dose to a human subject is described.