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Biomedical subjects

O Spigset

Publications and source records attributed to O Spigset.

At least 19 recordsLinked to original sources
PubMed2006

Pharmacokinetics of progesterone and its metabolites allopregnanolone and pregnanolone after oral administration of low-dose progesterone.

OBJECTIVES: To investigate the pharmacokinetics of progesterone, allopregnanolone and pregnanolone after treatment with a low oral dose of progesterone. METHODS: Eight postmenopausal women were given a single oral dose of 20 mg of micronised progesterone on Day 1 and 20 mg twice daily on Days 2-7. Blood samples for the analysis of progesterone, allopregnanolone and pregnanolone were collected, and pharmacokinetic parameters were calculated. RESULTS: After ingestion of a single dose, areas under the plasma concentration-time curve (AUC) from 0 to 12 h for progesterone, allopregnanolone and pregnanolone were 127%, 196% and 119% higher than the corresponding AUCs estimated to be caused by endogenous production. The maximum plasma concentration (Cmax) and the AUC values were significantly lower for pregnanolone than for progesterone and allopregnanolone. The trough concentrations at steady state (Css) were significantly higher than the baseline values, and Css for pregnanolone was significantly lower than for allopregnanolone and progesterone. Css for allopregnanolone was in the range of what is normally seen in the menstrual cycle. CONCLUSIONS: After ingestion of a low-dose of progesterone, the concentrations of allopregnanolone were in the same range as those of progesterone. Oral doses of 20 mg of progesterone twice daily to postmenopausal women produced allopregnanolone concentrations comparable to those achieved physiologically in premenopausal women. Low-dose oral progesterone may be used as a prodrug to allopregnanolone when the aim is to investigate low-dose allopregnanolone effects in humans.

Administration, Oral↗
PubMed2004

Platelet serotonin 5-HT2A receptor binding in patients with carcinoid tumor.

BACKGROUND: As carcinoid tumors produce and secrete serotonin, various serotonin markers in blood, plasma and urine have been used as diagnostic tools, and quantification of the urinary excretion of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) is the method most frequently used. METHODS: [3H]lysergic acid diethylamide ([3H]LSD) binding to the platelet serotonin 5-HT2A receptor was investigated in nine patients with carcinoid tumors. The possible effect of serotonin-rich food on the receptor binding was also investigated. RESULTS: B(max) for [3H]LSD binding was significantly lower in the carcinoid group than in the control group (mean +/- SD: 17.6 +/- 1.3 vs. 23.9 +/- 5.2 fmol/mg protein; p = 0.007). Kd for [3H]LSD binding was significantly higher in the carcinoid group than in the control group (median: 1.14 vs. 0.71 nmol/L; p = 0.03). B(max) was inversely related to the urinary 5-HIAA excretion, but the correlation did not reach statistical significance (r(s) = -0.57; p = 0.14). Intake of five bananas per day for one week had no effect on B(max) or Kd in healthy volunteers. CONCLUSIONS: The results are consistent with a down-regulation of the 5-HT2A receptor as a response to the high serotonin levels found in patients with carcinoid tumors. Intake of serotonin-rich food does not affect the receptor characteristics. Further studies are needed to determine whether the platelet 5-HT2A receptor status can be used as a supplement to urinary 5-HIAA and other biochemical variables in carcinoid tumors.

Aged↗
PubMed2003

Gender differences in drug effects: implications for anesthesiologists.

BACKGROUND: The gender aspect in pharmacokinetics and pharmacodynamics of anesthetics has attracted little attention. Knowledge of previous work is required to decide if gender-based differences in clinical practice is justified, and to determine the need for research. METHODS: Basis for this paper was obtained by Medline searches using the key words 'human' and 'gender' or 'sex,' combined with individual drug names. The reference lists of these papers were further checked for other relevant studies. RESULTS: Females have 20-30% greater sensitivity to the muscle relaxant effects of vecuronium, pancuronium and rocuronium. When rapid onset of or short duration of action is very important, gender-modified dosing may be considered. Males are more sensitive than females to propofol. It may therefore be necessary to decrease the propofol dose by 30-40% in males compared with females in order to achieve similar recovery times. Females are more sensitive than males to opioid receptor agonists, as shown for morphine as well as for a number of kappa (OP2) receptor agonists. On this basis, males will be expected to require 30-40% higher doses of opioid analgesics than females to achieve similar pain relief. On the other hand, females may experience respiratory depression and other adverse effects more easily if they are given the same doses as males. CONCLUSION: These examples illustrate that gender should be taken into account as a factor that may be predictive for the dosage of several anesthetic drugs. Moreover, there is an obvious need for more research in this area in order to further optimize drug treatment in anesthesia.

Adrenergic Agents↗
PubMed2001

Digitoxin medication and cancer; case control and internal dose-response studies.

BACKGROUND: Digitoxin induces apoptosis in different human malignant cell lines in vitro. In this paper we investigated if patients taking digitoxin for cardiac disease have a different cancer incidence compared to the general population. METHODS: Computer stored data on digitoxin concentrations in plasma from 9271 patients with cardiac disease were used to define a user population. Age and sex matched controls from the Norwegian Cancer Registry were used to calculate the number of expected cancer cases. RESULTS: The population on digitoxin showed a higher incidence of cancer compared to the control population. However, an additional analysis showed that the population on digitoxin had a general increased risk of cancer already, before the start on digitoxin. Leukemia/lymphoma were the cancer types which stood out with the highest risk in the digitoxin population before starting on digitoxin. This indicates that yet unknown risk factors exist for cardiovascular disease and lymphoproliferative cancer. An internal dose-response analysis revealed a relationship between high plasma concentration of digitoxin and a lower risk for leukemia/lymphoma and for cancer of the kidney/urinary tract. CONCLUSION: Morbidity and mortality are high in the population on digitoxin, due to high age and cardiac disease. These factors disturb efforts to isolate an eventual anticancer effect of digitoxin in this setting. Still, the results may indicate an anticancer effect of digitoxin for leukemia/lymphoma and kidney/urinary tract cancers. Prospective clinical cancer trials have to be done to find out if digitoxin and other cardiac glycosides are useful as anticancer agents.

Age Factors↗
PubMed2001

[One year's written drug information to a general practitioner].

BACKGROUND: It is a general impression that by far the greater part of drug information to general practitioners is provided by drug manufacturers rather than by independent sources. However, the extent of such information has not previously been quantified in Norway. MATERIAL AND METHODS: All written drug information received by a general practitioner in 1999 was registered. RESULTS: A total of 5,669 pages of drug information were received. Of these, 5,115 pages (90.2%) came from drug manufacturers. On average, 12 pages with drug advertisements and information on six different pharmaceutical products were received every day. INTERPRETATION: This study verifies that a very high proportion of the drug information to a general practitioner is provided by the pharmaceutical industry.

Advertising↗
PubMed2001

[The transfer of selective serotonin reuptake inhibitors to human milk].

BACKGROUND: This article presents an overview of the excretion of the SSRIs citalopram, paroxetine, fluoxetine, fluvoxamine and sertraline in breast milk. MATERIAL AND METHODS: Published articles on selective serotonin reuptake inhibitors and excretion in breast milk were identified and reviewed. In addition, drug concentrations were measured in milk from eight women using paroxetine (n = 4), citalopram (n = 3) or fluvoxamine (n = 1). RESULTS: Data from the literature indicate that the relative dose to the infant is lowest for fluvoxamine and sertraline, somewhat higher for paroxetine and highest for citalopram and fluoxetine. Adverse effects were reported in three of the 119 breastfed infants. Our own results show minimal excretion of fluvoxamine, small excretion of paroxetine and higher excretion of citalopram into breast milk. INTERPRETATION: If treatment with a selective serotonin reuptake inhibitor is started during the postpartum period, fluoxetine should not be the first alternative. High doses of citalopram should also be used with caution. However, when the use of an SSRI is clearly indicated in a breastfeeding woman, available data generally indicate that the positive effects of breast-feeding outweigh the risks for pharmacological effects in the infant.

Antidepressive Agents↗
PubMed2001

Olanzapine disposition in humans is unrelated to CYP1A2 and CYP2D6 phenotypes.

OBJECTIVE: Limited data suggest that CYP1A2 and CYP2D6 are involved in the metabolism of olanzapine. The purpose of this study was to further elucidate the role of these enzymes in the disposition of olanzapine in vivo. METHODS: Seventeen healthy non-smoking male volunteers were included in the study. Five subjects were CYP2D6 poor metabolisers (PMs), and 12 were CYP2D6 extensive metabolisers (EMs). All subjects received a single oral dose of 7.5 mg olanzapine, and serum concentrations were measured for 96 h using gas chromatography. A cross-over study was undertaken in the 12 CYP2D6 EMs who at least 2 weeks before or after the olanzapine dose received a single oral dose of 200 mg caffeine. The concentrations of caffeine and paraxanthine were measured in saliva 10 h after caffeine intake, and the paraxanthine/caffeine ratio was calculated as a measure of CYPIA2 activity. RESULTS: A threefold inter-individual variability in oral clearance (CLoral) and maximum serum concentration (Cmax) of olanzapine was observed and a 2.3-fold inter-individual variability in CYPIA2 activity. There was no significant correlation between CYP1A2 activity and oral clearance of olanzapine (r=-0.19, P=0.56). Moreover, there were no significant differences in any of the olanzapine pharmacokinetic parameters between the CYP2D6 PMs and EMs (CLoral=0.246 l h(-1) kg(-1) and 0.203 l h(-1) kg(-1), respectively, P=0.30). CONCLUSION: Neither CYP1A2 nor CYP2D6 seem to have a dominating role in olanzapine biotransformation after intake of a single dose.

Adult↗
PubMed2001

The major fluvoxamine metabolite in urine is formed by CYP2D6.

OBJECTIVE: Previous studies have shown that fluvoxamine is metabolized by CYP1A2 and CYP2D6, but there is no information on the impact the various CYP enzymes have on the different metabolic pathways of fluvoxamine biotransformation. The present study was designed to investigate this issue. METHODS: The major fluvoxamine metabolite, the 5-demethoxylated carboxylic acid metabolite, was analyzed in urine from 50 healthy volunteers after intake of a single oral dose of 50 mg fluvoxamine, and the formation clearance for the metabolite (CLm) was calculated. Of the subjects, 28 were non-smoking CYP2D6 and CYP2C19 extensive metabolizers (EMs), 12 were smokers and were thus considered to have an induced CYP1A2 activity, 5 were CYP2D6 poor metabolizers (PMs), and 5 were CYP2C19 PMs. In 11 of the non-smoking EMs, 200 mg caffeine was given at another occasion in order to calculate oral caffeine clearance as a measure of CYP1A2 activity. In addition, CLm was calculated in ten other subjects given increasing doses of fluvoxamine for 4 weeks. RESULTS: Oral clearance of fluvoxamine was significantly higher in smokers, and significantly lower in CYP2D6 PMs than in non-smoking EMs. CLm was 78% lower in CYP2D6 PMs than in the EMs. Smoking and being a CYP2C19 PM did not influence CLm. There was no significant correlation between oral caffeine clearance and CLm. CLm decreased with increasing fluvoxamine dosage, but the decrease in oral clearance was even higher. CONCLUSION: These results indicate that CYP2D6 catalyzes the major metabolic pathway of fluvoxamine, whereas CYP1A2 seems to catalyze other less important pathways. Both the CYP2D6 and the CYP1A2 pathways seem to be saturated in parallel with increasing fluvoxamine dosage.

Adult↗
PubMed2001

Influence of postmenopausal hormone replacement therapy on platelet serotonin uptake site and serotonin 2A receptor binding.

OBJECTIVE: To examine whether binding of [3H]paroxetine to the platelet serotonin transporter or binding of [3H]lysergic acid diethylamide (LSD) to the platelet 5-HT(2A) receptor are influenced by postmenopausal estrogen/progestogen treatment. METHODS: Twenty-three postmenopausal women with climacteric symptoms completed this double-blind, randomized, crossover study. The women received 2 mg of estradiol continuously during four 28-day cycles. In the last 14 days of each cycle, 10 mg of medroxyprogesterone acetate, 1 mg of norethindrone acetate, or placebo was given. Before treatment, as well as once during the last week of each treatment, blood samples were collected for analysis of [3H]LSD and [3H]paroxetine binding. The power of the study setup was 81%. The study had an effect size of 0.36, corresponding to the ability to detect a 15% difference in [3H]paroxetine and [3H]LSD binding between treatments with alpha =.05 and beta =.20, based on a previously reported standard deviation within cells of 20% of the mean binding values. RESULTS: The number of platelet receptors (B(max)), or the affinity of the radioligand to the receptor (K(d)), for [3H]paroxetine binding did not change during estrogen or estrogen-progestogen treatment, nor did B(max) or K(d) for [3H]LSD binding change during the different treatments. However, in a subgroup of depressed patients, the decrease in B(max) for [3H]LSD binding during treatment was significantly more pronounced than in the nondepressed subgroup (P <.05). CONCLUSION: Estrogen treatment with or without the addition of progestogen does not affect binding to the serotonin transporter or to the serotonergic 5-HT(2A) receptor in healthy postmenopausal women.

Blood Platelets↗
PubMed2001

Binding of [3H]paroxetine to serotonin uptake sites and of [3H]lysergic acid diethylamide to 5-HT2A receptors in platelets from women with premenstrual dysphoric disorder during gonadotropin releasing hormone treatment.

Changes in serotonergic parameters have been reported in psychiatric conditions such as depression but also in the premenstrual dysphoric disorder (PMDD). In addition, hormonal effects on serotonergic activity have been established. In the present study, binding of [3H]paroxetine to platelet serotonin uptake sites and binding of [3H]lysergic acid diethylamide ([3H]LSD) to platelet serotonin (5-HT)2A receptors were studied in patients with PMDD treated with a low dose of a gonadotropin releasing hormone (GnRH) agonist (buserelin) or placebo and compared to controls. The PMDD patients were relieved of premenstrual symptoms like depression and irritability during buserelin treatment. The number of [3H]paroxetine binding sites (Bmax) were significantly higher in the follicular phase in untreated PMDD patients compared to controls. When treated with buserelin the difference disappeared. No differences in [3H]LSD binding between the three groups were shown. The present study demonstrated altered platelet [3H]paroxetine binding characteristics in women with PMDD compared to controls. Furthermore, [3H]paroxetine binding was affected by PMDD treatment with a low dose of buserelin. The results are consistent with the hypothesis that changes in serotonergic transmission could be a trait in the premenstrual dysphoric disorder.

Adult↗