[The role of therapeutic drug monitoring--what to study and when?].
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Anti-Arrhythmia Agents↗
Biomedical subjects
Kari Laine
Publications and source records attributed to Kari Laine.
Effect of the novel anxiolytic drug deramciclane on the pharmacokinetics and pharmacodynamics of the CYP3A4 probe drug buspirone.
RATIONALE: Preliminary in vitro findings indicated that the novel anxiolytic drug, deramciclane is a substrate for the cytochrome P(450) (CYP) 3A4 isoenzyme. Moreover, its co-administration with buspirone, another anxiolytic drug, is likely in clinical practice. OBJECTIVES: The primary objective of the present study was to evaluate the in vivo effects of deramciclane on CYP3A4 activity as measured by buspirone pharmacokinetics. The secondary objective was to study the possible pharmacodynamic interaction between these two anxiolytic drugs. METHODS: Sixteen healthy subjects received 60 mg deramciclane or matched placebo for 8 days in this randomized, double-blind, cross-over study. On day 8 of both phases, the subjects received a 20-mg single dose of buspirone. Buspirone and its active metabolite, 1-pyrimidylpiperazine (1-PP), concentrations were measured for 24 h. Pharmacodynamic testing and measurement of plasma prolactin concentrations were carried out on day 7 and day 8 to assess the pharmacodynamic consequences of deramciclane and buspirone co-administration. RESULTS: Repeated administration of deramciclane had no effect on CYP3A4 activity as measured by buspirone pharmacokinetics. However, deramciclane administration caused an inhibition of the further, not CYP3A4-dependent, metabolism of 1-PP as evidenced by 84% increase in the AUC ( P<0.001) and 20% increase in the elimination half-life ( P=0.0012) of 1-PP. Deramciclane did not potentiate the buspirone-induced increase in prolactin secretion. No significant differences were found in the psychomotoric testing or the subjective maximum sedation between the deramciclane phase and the placebo phase, either before or after buspirone administration. Of 16 subjects, 5 experienced dizziness during both study phases. CONCLUSION: Deramciclane does not inhibit CYP3A4 activity as measured by buspirone pharmacokinetics, and there were no indications of relevant pharmacodynamic interaction after multiple doses of deramciclane and a single dose of buspirone.
Administration, Oral↗
Effects of exposure to selective serotonin reuptake inhibitors during pregnancy on serotonergic symptoms in newborns and cord blood monoamine and prolactin concentrations.
BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) have gained wide acceptance in the treatment of mental disorders in pregnant women, but there seems to be an increased risk for neonatal adaptation problems after exposure to SSRIs in late pregnancy. We aimed to investigate the perinatal sequelae of infants exposed to SSRIs during their fetal life and the relationship of these symptoms to the cord blood monoamine and prolactin concentrations. METHODS: We conducted a prospective, controlled, follow-up study with 20 mothers taking 20 to 40 mg/d of either citalopram or fluoxetine for depression (n = 10) or panic disorder (n = 10) and their infants and 20 matched controls not receiving psychotropic medication for confounding obstetric characteristics. Maternal cord blood and infant citalopram, fluoxetine, and norfluoxetine, cord blood monoamine and metabolite, and prolactin concentrations were measured. The newborns underwent standard clinical examination and specific assessment of serotonergic symptoms during the first 4 days of life and at the ages of 2 weeks and 2 months. RESULTS: There was a statistically significant (P =.008, V = 15, n = 20 for both groups), 4-fold difference in the serotonergic symptom score during the first 4 days of life between the SSRI group and the control group. The SSRI-exposed infants had significantly lower cord blood 5-hydroxyindoleacetic acid (5-HIAA) concentrations (P =.02, t31 = 2.57) compared with the control group. A significant inverse correlation (rs = -0.66, P =.007, n = 15) was seen between the serotonergic symptom score and the umbilical vein 5-HIAA concentrations in the SSRI-exposed but not the control infants. CONCLUSIONS: Infants exposed to SSRIs during late pregnancy are at increased risk for serotonergic central nervous system adverse effects, and the severity of these symptoms is significantly related to cord blood 5-HIAA levels.
Adult↗
Pharmacokinetics of fluoxetine and norfluoxetine in pregnancy and lactation.
BACKGROUND: The aim of this prospective clinical trial was to investigate the pharmacokinetics of fluoxetine and its active metabolite, norfluoxetine, during pregnancy, delivery, and lactation in mothers and their infants. METHODS: Eleven mothers taking fluoxetine and their infants were enrolled in the study. A control group of 10 women who were not taking psychotropic medication were prospectively matched for confounding obstetric characteristics at the time of delivery. Trough plasma samples and breast milk samples were collected from mother-infant pairs during pregnancy, at delivery, and up to 2 months after delivery in the fluoxetine group. The pregnancy outcome was recorded, and the growth and neurologic development of the children were followed up to the age of 1 year in both study groups. RESULTS: The fluoxetine dose from 20 mg to 40 mg once daily resulted in relatively low trough fluoxetine-norfluoxetine concentrations during pregnancy (range, 317-850 nmol/L). The mean norfluoxetine/fluoxetine metabolic ratio was 2.4-fold higher during late pregnancy than at 2 months after delivery (P = .0072). At delivery, the infant plasma fluoxetine and norfluoxetine concentrations were 65% and 72%, respectively, of those found in mothers. The mean estimated infant exposures from breast milk to fluoxetine-norfluoxetine were 2.4% and 3.8% of the maternal weight-adjusted daily dose at age 2 weeks and age 2 months, respectively. The pregnancy outcome, as well as the growth and neurologic development of all infants up to 1 year of age, was normal. CONCLUSION: Common clinical doses of fluoxetine resulted in relatively low concentrations of fluoxetine during pregnancy, which can be explained at least partly by increased demethylation of fluoxetine by cytochrome P450 (CYP) 2D6. This might indicate that these low blood levels could lead to therapeutic failure, and clinicians should be alert to this possibility so that depression in pregnancy is not undertreated.
Adult↗
Inhibition of cytochrome P450 2B6 activity by hormone replacement therapy and oral contraceptive as measured by bupropion hydroxylation.
AIM: Our objective was to study the effect of hormone replacement therapy and a combination oral contraceptive on the cytochrome P450 (CYP) 2B6 activity with bupropion (INN, amfebutamone) hydroxylation used as a probe reaction. METHODS: This was a 3-way crossover study with 12 healthy female volunteers. The first phase was a control phase, in which all subjects received a single 150-mg dose of bupropion (sustained release) without pretreatment. In the second and third phases, in randomized balanced crossover order, subjects received a 10-day pretreatment with either hormone replacement therapy, containing 2 mg estradiol valerate and 250 microg levonorgestrel, or an oral contraceptive, containing 30 microg ethinyl estradiol (INN, ethinylestradiol) and 150 microg desogestrel, and the bupropion dose was given 1 hour after the last hormone dose. The bupropion, hydroxybupropion, and hydrobupropion plasma concentrations were determined for up to 72 hours. RESULTS: The 10-day hormone replacement therapy pretreatment reduced the hydroxybupropion/bupropion area under the plasma concentration-time curve (AUC) ratio by 49% (P <.001; 95% confidence interval [CI], -58% to -40%) as a result of a marked 47% decrease (P <.001; 95% CI, -54% to -41%) in the AUC of hydroxybupropion. Moreover, the AUC of hydrobupropion was significantly (64%; P =.003; 95% CI, 22% to 106%) increased. The AUC of hydroxybupropion was also reduced after the oral contraceptive treatment but to a lesser extent (-31%; P <.001; 95% CI, -37% to -26%). However, the hydroxybupropion/bupropion AUC ratio was not significantly affected. CONCLUSIONS: Hormone replacement therapy markedly inhibited the CYP2B6-catalyzed hydroxylation of bupropion, whereas a combination oral contraceptive had only a modest effect on CYP2B6 activity. Patients receiving hormone replacement therapy or oral contraceptives may need dose adjustment when treated with drugs metabolized by CYP2B6.
Adult↗
Regional and habitat differences in 7-methyljuglone content of Finnish Drosera rotundifolia.
The concentration of 7-methyljuglone was studied in the round-leaved sundew Drosera rotundifolia L. collected from different regions in Northern Finland. Samples for analysis were collected from peat bogs and sandpit habitats. The mean concentration of 7-methyljuglone varied from 1.0 to 2.3% of dry weight. Variation between years in the amount of 7-methyljuglone was significant in plants growing on sand, and in the northernmost region studied. Overall, the variation in the production of 7-methyljuglone among different populations of round-leaved sundew in Northern Finland was rather low. The variation between years in the production of 7-methyljuglone was more significant.
Drosera↗
The effect of ethinyloestradiol and levonorgestrel on the CYP2C19-mediated metabolism of omeprazole in healthy female subjects.
AIMS: To study the effect of an oral contraceptive (OC) formulation containing ethinyloestradiol and levonorgestrel (LNG) (combination OC) or LNG alone on the CYP2C19-mediated hydroxylation of omeprazole in healthy females. METHODS: This was an open crossover study with three phases. In phase one, 10 healthy females received a single 40-mg dose of omeprazole. Thereafter the subjects received in a random order either 40 micro g ethinyloestradiol and 75 micro g LNG or 60 micro g LNG alone once daily for 10 days. On day 10, 1 h after the last OC dose, subjects received a single 40-mg oral dose of omeprazole. The plasma concentrations of omeprazole, 5'-hydroxyomeprazole and omeprazole sulphone were determined for up to 8 h. RESULTS: The use of combination OC increased the area under the curve (AUC) of omeprazole by 38% [95% confidence interval (CI) - 3.8, 80; P = 0.040] and caused a 48% increase (95% CI 28, 68) in the AUC ratio of omeprazole/5-hydroxyomeprazole. LNG alone did not effect the 5'-hydroxylation of omeprazole. Neither of the OC preparations seemed to have an inhibitory effect on the formation of omeprazole sulphone by CYP3A4. CONCLUSIONS: Oral contraceptives containing ethinyloestradiol but not those containing only LNG decrease CYP2C19 activity.
Adolescent↗
Effects of caffeine intake on the pharmacokinetics of melatonin, a probe drug for CYP1A2 activity.
AIMS: The aim of this study was to assess the influence of concomitant caffeine intake on the pharmacokinetics of oral melatonin, a probe drug for CYP1A2 activity. METHODS: Twelve healthy subjects, six smokers and six nonsmokers, were given melatonin (6 mg) either alone or in combination with caffeine (3 x 200 mg). Blood samples for the analysis of melatonin or caffeine and paraxanthine were taken from 1 h before until 6 h after intake of melatonin. Subjects were genotyped with respect to the CYP1A2*1F (C734A) polymorphism. RESULTS: When caffeine was coadministered the Cmax and AUC of melatonin were increased on average by 142% (P = 0.001, confidence interval on the difference 44, 80%) and 120% (P < 0.001, confidence interval on the difference 63, 178%), respectively. The inhibitory effect of caffeine was more pronounced in nonsmokers and in individuals with the *1F/*1F genotype. CONCLUSION: The results of this study revealed a pronounced effect of caffeine on the bioavailability of orally given melatonin, most probably due to inhibition of CYP1A2 activity.
Administration, Oral↗
A screening study on the liability of eight different female sex steroids to inhibit CYP2C9, 2C19 and 3A4 activities in human liver microsomes.
The aim of this study was to screen the inhibitory potential of different clinically used oestrogen and progestin hormones on CYP2C9, 2C19 and 3A4 activities in human liver microsomes. The degree of inhibition by desogestrel, 3-ketodesogestrel, 17-beta-oestradiol, gestodene, aethinyloestradiol, medroxyprogesterone acetate, norethisterone or L-norgestrel were studied at 100 microM on losartan oxidation (CYP2C9), R-omeprazole 5'-hydroxylation (CYP2C19) and R-omeprazole sulphoxidation (CYP3A4) with a 10-min preincubation with NADPH in human liver microsomes prepared from 6 individual genotyped donor livers. Aethinyloestradiol was found to be a potent inhibitor (55% mean inhibition; 95% CI 32% to 79%) of losartan oxidation (CYP2C9) and R-omeprazole 5-hydroxylation (70%; 63% to 77%) (CYP2C19), while it had little effect on R-omeprazole sulphoxidation (CYP3A4) activity. 17-beta-Oestradiol did not produce significant inhibition on any of the studied enzyme activities. Of the progestin hormones studied, gestodene and 3-ketodesogestrel were potent inhibitors of CYP2C19 (57%; 47% to 67% and 51%; 29% to 45%) and CYP3A4 (45%; 30% to 59% and 40%; 19% to 62%), but had little effect on the CYP2C9 activity. In addition, medroxyprogesterone acetate was found to inhibit CYP2C9 (55%; 45% to 65%), while not having significant effect on 2C19 or 3A4. In conclusion, the liability of clinically used female sex steroids to inhibit CYP2C9, 2C19 and 3A4 activities in human liver microsomes is very distinctive and these differences among both the oestrogen and progestin hormones may, at least in part, explain the variable results from clinical trials examining inhibitory effects of hormone replacement therapy and oral contraceptives on drug metabolism.
Aryl Hydrocarbon Hydroxylases↗
Effect of concomitant hormone replacement therapy containing estradiol and levonorgestrel on the pharmacokinetics of selegiline.
OBJECTIVE: The aim of this study was to investigate the effect of hormone-replacement therapy (HRT) on the pharmacokinetics of the selective monoamine oxidase B inhibitor selegiline and its primary metabolites desmethylselegiline and l-metamphetamine. METHODS: In this randomised, double-blind, cross-over trial, 12 healthy female subjects received once daily for 10 days either HRT containing 2 mg estradiol valerate and 250 microg levonorgestrel or matched placebo. On day 10, they took a single 10-mg oral dose of selegiline. The serum concentrations of selegiline, desmethylselegiline and metamphetamine were measured for 32 h. RESULTS: There was a 59% difference ( P=0.14) in the area under the serum concentration-time curve (AUC) of selegiline during the HRT compared with the placebo phase, but only a little or no concomitant reduction in the AUC of desmethylselegiline (-7%, P=0.071) or metamphetamine (2%, P=0.614) was observed. Maximum plasma concentration (C(max)) of selegiline was not changed, but a small, statistically significant, reduction in the C(max) of desmethylselegiline (-17%, P=0.03) was seen during the HRT phase. The C(max) of methamphetamine was slightly but not significantly reduced (-5%, P=0.06). The unchanged AUC ratios of desmethylselegiline/selegiline and metamphetamine/selegiline indicate that the primary metabolism of selegiline was not affected by HRT. All study treatments were well tolerated. CONCLUSION: Unlike oral contraceptives, HRT is not likely to have clinically significant pharmacokinetic interaction with selegiline.
Administration, Oral↗
Citalopram in pregnancy and lactation.
BACKGROUND: Although citalopram has gained wide acceptance in the treatment of depression and anxiety disorders, its use during pregnancy and lactation has been poorly characterized. The aim of this study was to examine the efficacy and safety of citalopram in relation to concentrations of citalopram and its metabolites during pregnancy and lactation. METHODS: Eleven mothers taking citalopram and their infants were enrolled in the study, and a control group of 10 women who were not taking medication were prospectively matched for confounding obstetric characteristics at the time of delivery. Plasma and breast milk samples were collected from mother/infant pairs during pregnancy, at delivery, and for up to 2 months after delivery. Trough plasma and breast milk concentrations of citalopram, desmethylcitalopram, and didesmethylcitalopram were measured by HPLC. The pregnancy outcome was recorded, and the neurodevelopment of children was monitored for up to 1 year. RESULTS: Although the citalopram dose of 20 mg to 40 mg once daily resulted in low maternal trough plasma concentrations (range, 46-214 nmol/L) and metabolites during pregnancy, only one subject required an increase of daily dose. The mean didesmethylcitalopram-desmethylcitalopram metabolic ratio was significantly higher during pregnancy (54%, P <.001) than at 2 months after delivery, indicating induction of cytochrome P450 (CYP) 2D6 during pregnancy. At delivery, the trough plasma citalopram, desmethylcitalopram, and didesmethylcitalopram concentrations in the infants were 64%, 66%, and 68% of the maternal concentrations, respectively. The citalopram and metabolite concentrations in the milk were 2- to 3-fold higher compared with maternal plasma concentrations, but the infant citalopram and metabolite plasma concentrations were very low or undetectable. The delivery outcome and the neurodevelopment of all infants up to the age of 1 year were normal. CONCLUSION: Even though the sample size was limited, results from this prospective clinical trial suggest uncomplicated pregnancy outcome in mothers using citalopram during pregnancy and minimal exposure of the infants to citalopram during lactation. However, maternal therapeutic drug monitoring of citalopram should be recommended to minimize fetal exposure.
Adult↗
Transplacental transfer of citalopram, fluoxetine and their primary demethylated metabolites in isolated perfused human placenta.
OBJECTIVE: To investigate the transplacental transfer and the effects of protein binding on the transfer of citalopram, desmethylcitalopram, fluoxetine and desmethylfluoxetine in the isolated perfused human placenta model. DESIGN: Prospective observational study. METHODS: Fifteen term human placentas were obtained immediately after delivery with maternal consent and a 2-hour non-recirculating perfusion cycle of a single placental cotyledon was set up. Citalopram (1230 nmol/L) and desmethylcitalopram (600 nmol/L) or fluoxetine (1455 nmol/L) and desmethylfluoxetine (1525 nmol/L) were added to the maternal reservoir and their appearance to the fetal circulation was followed by repeated measurements. To investigate the effect of protein binding on the transfer of citalopram and fluoxetine, nine additional perfusions were performed without albumin in the perfusion medium. Citalopram and desmethylcitalopram concentrations were measured by reversed-phase high performance liquid chromatography. Fluoxetine and desmethylfluoxetine concentrations was measured by gas chromatography and antipyrine (used as a reference compound) concentrations spectrophotometrically. RESULTS: The mean (SD) steady-state transplacental transfer (TPT(SS)%) for citalopram, desmethylcitalopram, fluoxetine and desmethylfluoxetine was 9.1%, 5.6% (P = 0.017 compared with citalopram), 8.7% and 9.1%, respectively, calculated as the ratio between the steady-state concentrations in fetal venous and maternal arterial sides. The TPT(SS)%s of citalopram, desmethylcitalopram, fluoxetine and desmethylfluoxetine were 86%, 50%, 88% and 91% of that of freely diffusable antipyrine. The absence of albumin significantly reduced the transfer of citalopram and fluoxetine (TPT(SS)% 1.1% and 4.8%, respectively) but not the transfer of antipyrine. CONCLUSION: Citalopram, fluoxetine and desmethylfluoxetine all cross the human placenta, and may, therefore, affect the perinatal outcome of infants exposed to these drugs during pregnancy. The transfer of desmethylcitalopram was significantly lower, which in the clinical setting may suggest lower fetal exposure of serotonin re-uptake inhibition by citalopram compared with fluoxetine. The presence of albumin was necessary for the transplacental transfer of both citalopram and fluoxetine.
Citalopram↗
Entacapone increases levodopa exposure and reduces plasma levodopa variability when used with Sinemet CR.
Entacapone is a catechol-O-methyltransferase (COMT) inhibitor used as an adjunct to levodopa/dopa decarboxylase inhibitors in the treatment of Parkinson's disease. Entacapone increases the bioavailability and reduces the daily variation of plasma levodopa when administered with standard levodopa preparations. These parameters were studied when entacapone was administered with a controlled-release levodopa preparation after repeated administrations throughout the day in 16 healthy male volunteers. On 2 test days, 200 mg entacapone or placebo was administered 4 times during the day at 4-hour intervals concomitantly with a single dose of controlled-release levodopa/carbidopa 100 mg/25 mg (Sinemet CR). Plasma levodopa, 3-O-methyldopa (3-OMD), and carbidopa concentrations were measured before intake of the medication and then every 30 minutes for 16 hours (until midnight), and less frequently up to 24 hours after the first levodopa dose. The minimum, maximum, and average concentration of levodopa; the daily variation of levodopa concentration; and the area under the time concentration curve (AUC) were calculated. The mean (+/-SD) plasma levodopa AUC was 39% (P = 0.0001) higher with entacapone (11,802 +/- 1454 ng/hour/mL) compared with placebo (8465 +/- 927 ng/hour/mL). The daily variation of plasma levodopa was reduced by about 25% with entacapone (P < 0.01). Entacapone significantly reduced plasma 3-OMD concentration by about 50% (P = 0.0001), indicating marked COMT inhibiting activity. There were no differences in plasma carbidopa concentrations. Entacapone significantly increased the bioavailability of levodopa and reduced its daily variation when administered concomitantly with a controlled-release levodopa preparation.
Adult↗