Claude L. Holder

Trace analysis of the antihistamines methapyrilene hydrochloride, pyrilamine maleate and triprolidine hydrochloride monohydrate in animal feed, human urine and wastewater by high-performance liquid chromatography and gas chromatography with nitrogen-phosphorus detection.

Toxicological evaluation of the antihistamines methapyrilene hydrochloride, pyrilamine maleate, and triprolidine hydrochloride monohydrate using methapyrilene hydrochloride as the positive indicator was investigated as part of a structure-activity relationship study in rats and mice. Prerequisites for the toxicological tests were the development of analytical procedures to certify the dose, homogeneity and stability of the drugs in animal feed and to monitor human urine for possible exposure and to ensure removal of the test agents from wastewater prior to its discharge into the environment. A high-performance liquid chromatographic (HPLC) system was developed using a fluorescence detector for the determination of methapyrilene hydrochloride and pyrilamine maleate in feed at levels as low as 100 ng/g and in human urine as low as 1 ng/g. An HPLC-UV procedure was developed for the determination of triprolidine hydrochloride monohydrate in feed at levels as low as 10 micrograms/g. Data concerning p-values, extraction efficiencies from feed and stability experiments in feed are presented for these antihistamines. A gas chromatographic procedure using a nitrogen-phosphorus detector was also developed for determining the three antihistamines in admixture in wastewater at levels as low as 10 ng/g.

Metabolism of methapyrilene by Fischer-344 rat and B6C3F1 mouse hepatocytes

1. Suspension cultures of freshly isolated F344 rat and B6C3F1 mouse hepatocytes were compared for their ability to transform various concentrations of methapyrilene (MP). 2. MP metabolites were isolated and purified by h.p.l.c., and were identified by comparing their chromatographic and mass spectral properties with those of authentic standards. 3. Both rat and mouse hepatocytes transformed MP to tentatively identified 2-thiophenecarboxylic acid (I), and definitively identified mono-N-desmethyl methapyrilene glucuronide (II), methapyrilene glucuronide (III), methapyrilene N-oxide (V), and mono-N-desmethyl methapyrilene (VII).

Pharmacokinetics of doxylamine, a component of Bendectin, in the rhesus monkey.

The elimination of doxylamine and metabolites was determined after iv administration of [14C]doxylamine succinate at 0.7 and 13.3 mg/kg to the adult female rhesus monkey. Although the total recovery of radioactivity was the same for the low- and high-dose studies (90.2%), the rate of plasma elimination of doxylamine and its demethylated metabolite (desmethyldoxylamine) was slower for the high dose group. The 24 hr urinary excretion of doxylamine metabolites, desmethyl- and didesmethyldoxylamine, was significantly increased and the polar doxylamine metabolites were significantly decreased as the iv doxylamine succinate dose was increased. The plasma elimination of gas chromatograph (GC)-detected doxylamine was determined after oral administration of Bendectin (doxylamine succinate and pyridoxine hydrochloride) at 7, 13.3, and 27 mg/kg to adult female rhesus monkeys. As the dose increased, the clearance of doxylamine decreased. A statistically evaluated fit of the oral data to a single-compartment, parallel first-order elimination model and a single-compartment, parallel first- and second-order (Michaelis-Menten) elimination model indicated that the more complex model containing the second-order process was most consistent with the observed elimination data.

Determination of sodium saccharin in animal feed, wastewater and human urine by high-pressure liquid chromatography.

Analytical methods are described for sodium saccharin in animal feed, wastewater and human urine at levels as low as 10, 0.1 and 10 ppm, respectively. Samples of animal feed and wastewater are subjected to liquid-liquid partitioning then the feed is further cleaned up on a column of silica gel prior to analysis by high-pressure liquid chromatography (HPLC) using a paired-ion mobile phase and an ultraviolet detector set at 230 nm. Samples of human urine require a cleanpu on a column of XAD-2 prior to the partitioning and silica gel steps as well as an adjustment in the composition of the mobile phase to quantify saccharin. Data concerning partition values and the stability of sodium saccharin in animal feed are also presented.

In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondrial defect model

Summary The uptake and distribution of intramuscularly (IM) administered tritium-labeled polysulfated glycosaminoglycan ( 3 H-PSGAG) in serum, synovial fluid, and articular cartilage of eight horses was quantitated, and hyaluronic acid (HA) concentration of the middle carpal joint was evaluated in a pharmacokinetic study. A full-thickness articular cartilage defect, created on the distal articular surface of the left radial carpal bone of each horse served as an osteochondral defect model. 3 H-PSGAG (500 mg) was injected IM, between 14 and 35 days after creation of the defects. Scintillation analysis of serum and synovial fluid, collected from both middle carpal joints at specific predetermined times up to 96 hours post-injection, revealed mean 3 H-PSGAG concentrations peaked at 2 hours post-injection. 3 H-PSGAG was detected in cartilage and subchondral bone 96 hours post-injection in samples from all eight horses. There were no statistically significant differences in 3 H-PSGAG concentration of synovial fluid or cartilage between cartilage defect and control (right middle carpal) joints. HA assay of synovial fluid revealed concentrations significantly increased at 24, 48, and 96 hours post-injection in both joints. The concentration nearly doubled 48 hours post-injection. However, no statistically significant differences were found between synovial concentrations of HA in cartilage defect and control joints. 3 H-PSGAG administered IM to horses, was distributed in the blood, synovial fluid, and articular cartilage. HA concentrations in synovial fluid increased after IM administration of polysulfated glycosaminoglycan.

Pharmacokinetics of doxylamine given as bendectin® in the pregnant monkey and baboon

The object of the present study was to determine the maternal plasma pharmacokinetics of doxylamine (the antihistamine component of Bendectin) following Bendectin administration. Bendectin was administered daily, po, at a dosage approximately 10 times the maximum human therapeutic dosage (7 mg/kg/day) throughout organogenesis (approximately days 22 through 50 of gestation) to three cynomolgus monkeys, four rhesus monkeys, and five baboons. Two pharmacokinetic experiments were performed in each animal, one on the first day of treatment and one on the last day of treatment. Although this study was not designed specifically as a teratologic examination, no morphologic abnormalities were observed when the fetuses were examined on approximately day 100 of gestation. A single-compartment, parallel first- and second-order elimination model was used to analyze the data. Although considerable interindividual variation was evident, no significant differences between species were observed when the half-life for the absorption of doxylamine from the gut or the elimination of doxylamine and metabolites from the plasma were compared. The plasma elimination half-lives and the clearance values were not altered by the 29 days of Bendectin treatment for any of the species. Only the half-life for the absorption of doxylamine in the baboon was reduced by daily dosing with Bendectin, but this did not alter doxylamine elimination. Thus, the pharmacokinetics of doxylamine administered as Bendectin were similar in the three nonhuman primate species examined and were not altered by repeated daily administration.

Trace determination of the antihistamines tripelennamine hydrochloride, thenyldiamine hydrochloride, and chlorothen citrate in admixture in animal feed, human urine, and wastewater by high-pressure liquid chromatography and use of a fluorescence detector

Tripelennamine hydrochloride, thenyldiamine hydrochloride, and chlorothen citrate have been used as antihistamines and for the treatment of asthma and bronchitis. Toxicological evaluation of these drugs was scheduled as part of a structure-activity relationship study of antihistamines in rats and mice, because of the paucity of such information. Prerequisite for the evaluation was the development of analytical chemical procedures to certify the concentration, homogeneity, and stability of the drugs in dosed feed, to monitor the urine of laboratory personnel to signal their possible exposure to the drugs, and to monitor the wastewater to ensure that the test agents were not discharged into the environment. A high-pressure liquid chromatographic procedure with fluorescence detection was developed for determination of the three antihistamines in admixture in animal feed, human urine, and wastewater at levels of 500, 10 and 10 ng g , respectively. Data on the partition values and use of a silica gel column to aid in the clean-up of sample extracts from the three substrates are reported for the three test agents. Extraction efficiencies and data concerning the stability of tripelennamine hydrochloride and thenyldiamine hydrochloride in animal feed are presented. Description of a new route for synthesis of chlorothen citrate and ancillary data concerning the gas chromatographic analysis for the three drugs in admixture in animal feed at levels as low as 10 mug g are also reported.

Formation of artifactual metabolites of doxylamine following acid hydrolysis

This study describes the use of gas chromatographic-mass spectrometric, high-performance liquid chromatographic and capillary column gas chromatographic separation techniques in demonstrating the production of several artifactual compounds reported in the literature as metabolites of doxylamine. Rhesus monkey urinary extracts which contained doxylamine and doxylamine metabolites were examined with and without acid hydrolysis. The production of 1-phenyl-1-(2-pyridinyl)ethanol and 1-phenyl-1-(2-pyridinyl)ethylene under acid hydrolysis conditions was demonstrated. These artifactual products were shown to originate from the acid hydrolysis of 2-[1-phenyl-1-(2-pyridinyl)ethoxy] acetic acid and not from doxylamine.

High-performance liquid chromatography of the antihistamine pyrilamine and its N-oxide using electrochemical detection.

The electrochemical behavior of the over-the-counter antihistamine drug pyrilamine and its N-oxide analogue, have been studied by several voltammetric methods. Cyclic voltammograms of pyrilamine maleate in 0.1 M ammonium acetate at pH 7.0 indicated a quasi-reversible electrode process by observing a wave at + 0.85 V and + 1.30 V in the initial anodic sweep followed by a wave at - 1.30 V versus Ag/AgCl. Differential pulse and hydrodynamic voltammetry of pyrilamine and the N-oxide were examined to determine oxidation potentials for use in high-performance liquid chromatography with electrochemical detection (HPLC-ED). Differentiation between pyrilamine and its N-oxide was achieved in HPLC-ED analyses at a detection potential of + 0.7 V and + 0.9 V versus Ag/AgCl with tandem ultraviolet detection at 254 nm. Utility of the HPLC-ED method was demonstrated by the analysis of pyrilamine and the N-oxide in microbial biotransformation samples.

Comparison of the metabolism and elimination of pyrilamine maleate in the rat, mouse and female rhesus monkey

Abstract Elimination and metabolic profiles of the O -glucuronide conjugated products of pyrilamine and their nonconjugated O -dealkylated and N -desmethyl pyrilamine products were determined after the oral administration of ( 14 C)-pyrilamine maleate to Fischer 344 rats, B 6 C 3 F1 mice and female rhesus monkeys by stomach tube or i.v. The total cumulative urinary and fecal pyrilamine products were determined. The conjugated pyrilamine metabolites, isolated and identified were the glucuronide products of O -dealkylated pyrilamine and ring-hydroxylated pyrilamine, and the nonconjugated metabolites were predominately the N -desmethylpyrilamine and O -dealkylated pyrilamine and their ring-hydroxylated products. Statistically significant differences were observed in the percentages of the conjugated and nonconjugated metabolites of pyrilamine excreted by the three species studied.