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Biomedical subjects

D L Azarnoff

Publications and source records attributed to D L Azarnoff.

At least 37 records · Page 2Linked to original sources
PubMed1978

Quantitation of lidocaine and its deethylated metabolites in plasma and urine by gas chromatography-mass fragmentography.

A sensitive, precise and accurate method for simultaneous quantitation of lidocaine and its deethylated metabolites by gas chromatography-mass fragmentography has been developed. Propyl derivatives of the deethylated metabolites are formed directly in either plasma or urine by treatment with propionaldehyde and sodium cyanoborohydride. The propyl derivatives and unchanged lidocaine are extracted, separated by gas chromatography and quantitated by mass fragmentography using mepivacaine as the internal standard. Quantitation of these compounds to levels as low as 50 ng/ml body fluid has been achieved with coefficients of variation less than 10%.

Chromatography, Gas↗
PubMed1978

Quantitation of chlordiazepoxide and its metabolites in biological fluids by thin-layer chromatography.

Chlordiazepoxide and its 4 major metabolites were assayed after separation by thin-layer chromatography following extraction from biological fluids. The compounds become intensely fluorescent in the presence of red, fuming nitric acid. The resulting compounds are quantitated with a spectrodensitometer with a fluorescent attachment. The sensitivity varies between 0.05 and 0.1 microgram. The coefficient of variation is 1.4% for assays in urine and 6.4% in serum.

Benzodiazepinones↗
PubMed1978

Identification of methotrexate and folic acid analogs by mass spectrometry.

Methotrexate and folic acid analogs are polar molecules and attempts to obtain electron impact and chemical ionization mass spectra of these compounds by several laboratories have failed. We have found that methylation of this important class of compounds with diazomethane produces derivatives which are sufficiently volatile to allow their mass spectra to be recorded. The mass spectra of the methyl derivatives of five compounds, 4-amino-4-deoxy-N10-methylpteroylglutamic acid, 4-amimo-4-deoxypteroylglutamic acid, pteroylglutamic acid, 4-amino-4-deoxypteroic acid and N10-methylpteroylglutamic acid are presented, and the fragmentation pathways of these compounds discussed.

Folic Acid↗
PubMed1978

Correlation between plasma diphenhydramine level and sedative and antihistamine effects.

The sedative and antihistamine effects of diphenhydramine were assessed in relation to plasma concentration after placebo, diphenhydramine 50 mg intravenously, and diphenhydramine 50 mg orally to each of 6 healthy volunteers on three separate occasions. Diphenhydramine plasma elimination t1/2 was 3.0 to 4.3 hr, volume of distribution was 188 to 336 L, and clearance was 637 to 1,014 ml/min. Systemic bioavailability of the oral preparation ranged from 0.26 to 0.60. The sedative effect of intravenous diphenhydramine differed from that of placebo only during the first 3 hr. Antihistamine effect, as measured by reduction of histamine provoked skin wheal diameter, was significantly different from that of placebo for at least 8 hr. There was a positive correlation between plasma diphenhydramine level and sedative and antihistamine effects, but wide variation in the extent and rate of change of these effects were observed between the subject. There appears to be a concentration range of 25 to 50 ng/ml, within which there is significant antihistamine effect without significant sedation.

Administration, Oral↗
PubMed1978

Kinetics, salivary excretion of amphetamine isomers, and effect of urinary pH.

Amphetamine was administered to healthy subjects as the racemic mixture and as (+)- and (-)-isomers under conditions of urine acidification and alkalinization. Plasma and saliva concentration of each isomer was measured and the kinetics of the individual isomers were determined. (+)-amphetamine was eliminated more rapidly than the (-)-isomer. The difference in half-life between isomers was maximal under basic urinary pH conditions. Saliva amphetamine levels were higher than plasma levels and in the postabsorptive phase were predictably proportional to plasma drug levels.

Adult↗
PubMed1978

Pamatolol: phase I evaluation of the pharmacodynamics of a cardioselective beta adrenoceptor blocking drug.

A Phase I evaluation of a new adrenoceptor blocker, pamatolol, was performed in 10 healthy male volunteers. Minor reductions in standing and exercise and isoproterenol-induced increases in heart rate were observed with the 10-mg oral dose and appeared maximal with the 400-600 mg dose. The rate of decline of effect averaged 1.5% of the exercise heart rate/hr. Neither resting systolic time intervals nor post-exercise pulmonary function was affected by this dose range of pamatolol. Based on the latter responses and the isoproterenol dose response curve, we tentatively conclude that pamatolol is relatively cardioselective in man.

Adolescent↗
PubMed1978

Theophylline bioavailability following chronic dosing of an elixir and two solid dosage forms.

Theophylline bioavailability following chronic dosing of an elixir and two commercial tablet formulations (I and II) relative to an acute dose of elixir was evaluated in healthy volunteers. Both tablet formulations contained ephedrine. In addition, Tablet I contained hydroxyzine hydrochloride, and Tablet II contained phenobarbital. The mean area under the serum concentration-time curve (AUC) calculated either from time 0 leads to infinity for a single dose or over one dosing interval after repetitive doses was the highest after chronic administration of the elixir. The AUC after chronic elixir, in fact, was statistically different from the values after acute elixir (p less than 0.05) and Tablet II (p less than 0.05). There was, however, a large variation in the elimination half-life among the four theophylline treatments. The mean t 1/2 was the longest after chronic elixir followed by Tablet I, Tablet II, and acute elixir. The AUC values for the four treatments, when corrected for differences in t 1/2, were no longer significantly different, indicating that the extent of theophylline absorption was essentially the same from all three tested products. The time to peak and the peak serum concentration also did not differ among treatments. The prolongation in t 1/2 following chronic treatment with the elixir and its subsequent shortening during tablet administration suggest an initial inhibition followed by induction of theophylline metabolism. The changes may be due to the prolonged treatment with theophylline itself or the other drug ingredients in the dosage form.

Adult↗
PubMed1978

Separation and identification of impurities in parenteral methotrexate dosage forms.

Eleven lots of parenteral methotrexate (MTX) dosage forms from two manufactures have been analyzed and found to be 93.4% +/- 2.1% (SD) pure by a new procedure employing a DEAE-cellulose column adapted for high performance liquid chromatography instrumentation. In addition to 4-amino-10-methylpteroic acid and N10-methylpteroylglutamic acid, which were previously identified contaminants, and benzyl alcohol, which was added as a preservative, we have also isolated and identified 2,4-diamino-6-methylpteridine, 2,4-diamino-6-bromomethylpteridine, and p-methylaminobenzoic acid. Another impurity has tentatively been identified as 4-amino-10-methylpteroic acid amide. The individual impurities vary from 0.1% to 4.8% of the ultraviolet absorbing material which elutes from the column. Additional impurities were detected by gas chromatography-mass spectrometry. Since "high-dose" therapy may involve the administration of up to 20 g of MTX/day, the effect of the impurities present in these dosage forms on the course of the patient's therapy should be determined.

Chromatography, High Pressure Liquid↗
PubMed1978

Hepatic peroxisome proliferation: induction by BR-931, a hypolipidemic analog of WY-14,643.

Administration of BR-931, an ethanolamine derivative of Wy-14,643 [4-chloro-6-(2,3-xylidino)-2-pyrimidinythio]acetic acid, at a dietary concentration of 0.125% for 3 weeks to male F-344 rats, resulted in a significant enlargement of the liver. The hepatomegaly appeared to be due to liver cell hyperplasia and hypertrophy resulting, in part, from peroxisome and smooth endoplasmic reticulum proliferation. The hepatic catalase and carnitine acetyltransferase activities increased significantly in association with peroxisome proliferation. The hepatomegaly and peroxisome proliferation induced by BR-931 were comparable in degree to those resulting from feeding of an equivalent dose of Wy-14,643. All these hepatic effects were reversible when the drugs were withdrawn from the diet. Screening of new compounds for hepatic peroxisome proliferation and for increases in peroxisome-associated enzymes may prove to be an adjunct to evaluating their potency as hypolipidemic agents, in view of frequent association between hepatic peroxisome proliferation and hypolipidemia.

Acetamides↗
PubMed1977

Glutethimide and 4-OH glutethimide: pharmacokinetics and effect on performance in man.

The relationship between the plasma concentration of glutethimide (G) and the change from baseline of the standard error of the mean (deltaSDE) of a tracking test was determined in 7 volunteers. There was excellent positive correlation (r = 0.91) between log G and log deltaSDE and good correlation between log G and deltaSDE (r = 0.77). The metabolite, 4 hydroxyglutethimide, did not contribute significantly to the effect of G administered in therapeutic doses. No trend in performance versus level was found with 5 other tests (finger tapping, card sorting, digit substitution, subtraction, and subjective perception of drowsiness). Although the numbers were small, when the volunteers were divided into smokers (3) and nonsmokers (4) G decreased tracking ability to a greater extent in smokers than in nonsmokers.

Adult↗
PubMed1977

Bioavailability of digoxin-hydroquinone complex: a new oral digoxin formulation.

A new oral digoxin formulation, a digoxin-hydroquinone complex (99% dissolution at 5 min), was evaluated in 12 healthy human volunteers with reference to bioavailability and extent and time of peak serum digoxin levels. This preparation was compared with a commercial digoxin tablet (26% dissolution at 5 min), digoxin elixir, and a parenteral digoxin solution. Bioavailability was assessed by the 24-hr area under the serum digoxin-time curve and 48-hr digoxin excretion in urine. The bioavailability of the complex was similar to that of the elixir but not statistically different from that of the tablet. The tablet was less bioavailable than the elixir. There was less interindividual variation in bioavailability with the complex than with the elixir. Peak serum digoxin levels were higher with the complex than the tablet and were achieved more quickly.

Administration, Oral↗
PubMed1977

Theophylline bioavailability: a comparison of the oral absorption of a theophylline elixir and two combination theophylline tablets to intravenous aminophylline.

The bioavailability of theophylline from single doses of an elixir (Elixophyllin) and two different tablet formulations, as compared to intravenous aminophylline, was studied with a crossover design in 12 normal volunteers. Both tablet formulations (Marax and Tedral) contain ephedrine. Marax contains hydroxyzine hydrochloride, and Tedral contains phenobarbital. The absorption of theophylline was most rapid from the elixir, whereas that from Marax was faster than that from Tedral. The peak concentrations of theophylline after administration of the 3 oral dosage forms were in the order, elixir greater than Marax greater than Tedral, however, the time to achieve peak concentration was highly variable and did not differ significantly among the 3 products. On the basis of area under the serum concentration-time curves, the absorption of theophylline from the elixir and from Marax was essentially complete. The area under the serum concentration curve after administration of Tedral was significantly less than that after intravenous aminophylline, elixir, and Marax; however, when the individual areas under the concentration curves were adjusted for intrasubject variation in elimination rate constant, the mean area under the concentration curve after Tedral no longer differed significantly from those of the intravenous and other two oral products. A large degree of intersubject variation in the oral absorption of theophylline was observe din this study. Therefore, in addition to the well-documented, large individual variation in the serum clearance of theophylline, intersubject differences in the absorption of the drug is another factor that complicates proper adjustment of the dose in oral theophylline therapy.

Administration, Oral↗