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Biomedical subjects

C A Haller

Publications and source records attributed to C A Haller.

6 recordsLinked to original sources
PubMed2006

Clinical pharmacology of 1,4-butanediol and gamma-hydroxybutyrate after oral 1,4-butanediol administration to healthy volunteers.

1,4-Butanediol (BD) is converted to gamma-hydroxybutyrate (GHB) after ingestion, and is associated with cases of dependence, coma, and death. The pharmacology of BD after oral ingestion has not been described in humans. Eight healthy volunteers (five men) were administered 25 mg/kg BD in a single oral dose after an overnight fast in a double-blinded, placebo-controlled, crossover study. Vital signs were monitored, and serial blood samples collected over 24 h for gas chromatography-mass spectrometry analysis of BD and GHB levels. Subjective mood and symptoms responses were assessed by visual analog scale. All subjects completed the study without significant adverse effects. BD was quickly absorbed and cleared, with time to maximal plasma concentration of 24+/-12 min, and elimination half-life (T(1/2)) of 39.3+/-11 min. BD was extensively converted to GHB, with a mean maximum GHB concentration of 45.6+/-19.7 mg/l reached 39.4+/-11.2 min after BD ingestion. GHB T(1/2) averaged 32.3+/-6.6 min. Some subjects exhibited slow oral clearance of BD, which tended to correlate with a variant haplotype of the alcohol dehydrogenase gene ADH-IB G143A. Mean CL/F was 151.5+/-176.5 ml/min kg for four subjects with variant haplotype versus 598.8+/-446.6 ml/min kg for four wild-type subjects (P=0.061). Subjects reported feeling less awake and alert, less able to concentrate, and more lightheaded in the first 90 min after BD ingestion. Pulse oximetry readings were lower 45 min after BD dosing with a mean oxygen saturation of 98.5% with BD versus 99.6% with placebo (P=0.031). Transient increases in mean systolic and diastolic blood pressure were observed, but other vital signs remained unchanged. BD was extensively converted to GHB after oral administration, but significant inter-individual variability in the rate of metabolism, possibly related to variants in ADH-IB, was observed. At the modest dose studied, significant clinical effects were not seen.

Administration, Oral↗
PubMed2005

Mechanistic pharmacokinetic modelling of ephedrine, norephedrine and caffeine in healthy subjects.

AIM: The combination of ephedrine and caffeine has been used in herbal products for weight loss and athletic performance-enhancement, but the pharmacokinetic profiles of these compounds have not been well characterized. This study aimed to develop a mechanistic model describing ephedrine, norephedrine, and caffeine pharmacokinetics and their interactions in healthy subjects. METHODS: The pharmacokinetic model was developed based on the simultaneous modelling using plasma samples gathered from two clinical trials. The treatments consisted of single-doses of pharmaceutical caffeine and ephedrine, given alone or together, and an herbal formulation containing both caffeine and ephedrine. We used a mixed-effect statistical model and the program NONMEM to take account of intersubject variability. RESULTS: Three hundred and seventy-nine ephedrine, 352 norephedrine, 417 caffeine plasma concentrations and 40 ephedrine urine concentrations were obtained from 24 subjects. A one-compartment model with first-order absorption described the caffeine data. Caffeine clearance was 0.083 l min(-1) (CV 38%) and decreased to 0.038 l min(-1) in presence of oral contraceptive therapy, its volume of distribution was 38.6 l (CV 20%) and its absorption rate constant was 0.064 l min(-1) (CV 50%). A four-compartment model described the pharmocokinetics of ephedrine and norephedrine. Ephedrine was eliminated mostly renally, with a clearance of 0.34 l min(-1) (CV 11%), and a volume of distribution of 181 l (CV 19%). Nonlinearity in the conversion of ephedrine to norephedrine was observed. Different models showed that the simultaneous administration of caffeine, or the amount of caffeine in the absorption compartment, was associated with a slower rate of absorption of ephedrine. A 32% greater relative bioavailability of herbal compared with pharmaceutical ephedrine administration was observed. CONCLUSIONS: We describe a mechanistic model for ephedrine, norephedrine and caffeine pharmacokinetics and their interactions. The relative bioavailability of ephedrine differed between the herbal supplement compared with the pharmaceutical formulation. Concomitant ingestion of caffeine slowed the absorption rate of ephedrine, which is mainly related to the amount of the former in the absorption compartment. A saturable process appears to be involved in the metabolism of ephedrine to norephedrine.

Administration, Oral↗
PubMed2000

Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids.

BACKGROUND: Dietary supplements that contain ephedra alkaloids (sometimes called ma huang) are widely promoted and used in the United States as a means of losing weight and increasing energy. In the light of recently reported adverse events related to use of these products, the Food and Drug Administration (FDA) has proposed limits on the dose and duration of use of such supplements. The FDA requested an independent review of reports of adverse events related to the use of supplements that contained ephedra alkaloids to assess causation and to estimate the level of risk the use of these supplements poses to consumers. METHODS: We reviewed 140 reports of adverse events related to the use of dietary supplements containing ephedra alkaloids that were submitted to the FDA between June 1, 1997, and March 31, 1999. A standardized rating system for assessing causation was applied to each adverse event. RESULTS: Thirty-one percent of cases were considered to be definitely or probably related to the use of supplements containing ephedra alkaloids, and 31 percent were deemed to be possibly related. Among the adverse events that were deemed definitely, probably, or possibly related to the use of supplements containing ephedra alkaloids, 47 percent involved cardiovascular symptoms and 18 percent involved the central nervous system. Hypertension was the single most frequent adverse effect (17 reports), followed by palpitations, tachycardia, or both (13); stroke (10); and seizures (7). Ten events resulted in death, and 13 events produced permanent disability, representing 26 percent of the definite, probable, and possible cases. CONCLUSIONS: The use of dietary supplements that contain ephedra alkaloids may pose a health risk to some persons. These findings indicate the need for a better understanding of individual susceptibility to the adverse effects of such dietary supplements.

Adolescent↗
PubMed1999

Breastfeeding: 1999 perspective.

Although the vast majority of pediatricians agree that breastfeeding is the preferred form of infant feeding, a large number of infants are still exclusively formula-fed or rarely breastfed for an extended period of time. This review explores focuses on data that speak to mothers' decisions to initiate and continue breastfeeding. Current research focuses on the immunomodulatory effects of breast milk, especially its protective benefits as relates to infection and allergy. The evidence clearly indicates that pediatricians must continue to play a critical role in the promotion of breastfeeding.

Breast Feeding↗
PubMedDate not supplied

Effect of epidural and subarachnoid injections of a 10% butamben suspension.

Three groups of dogs were each given repeat epidural injections of a 10% butamben suspension. A fourth group received a single subarachnoid injection of the butamben suspension. All dogs were later sacrificed and the spinal cord, meninges and spinal nerves were examined. The dogs receiving the epidural injections had no pathology. Those dogs that received subarachnoid injections had adhesive arachnoiditis. None demonstrated any evidence of neurolysis. Two cancer patients who had each received multiple injections of a 10% butamben suspension for the successful treatment of cancer pain prior to their deaths had autopsies and the spinal cords, meninges and spinal nerves were examined. No significant pathology due to the butamben was noted. Epidural butamben does not appear to cause any local tissue damage provided that subarachnoid needle placement has been ruled out. Subarachnoid butamben should be avoided.

Anesthetics, Local↗