Drugs online research references
Clin Pharmacol Ther. 2000 May;67(5):567-76.
Relationship of paroxetine disposition to metoprolol metabolic ratio and CYP2D6*10 genotype of Korean subjects.
Yoon YR, Cha IJ, Shon JH, Kim KA, Cha YN, Jang IJ, Park CW, Shin SG, Flockhart DA, Shin JG.
Department of Pharmacology, Inje University College of Medicine and Clinical Pharmacology Center, Pusan Paik Hospital, Korea.
OBJECTIVE: To evaluate the relationship between the metabolic ratio (MR) of metoprolol, CYP2D6*10B genotype, and the disposition of paroxetine in Korean subjects. METHODS: A single 40-mg dose of paroxetine was administered orally to one poor metabolizer and 15 healthy subjects recruited from 223 Korean extensive metabolizers whose phenotypes were predetermined by use of the metoprolol MR. Genotypes were determined by allele-specific polymerase chain reaction and the GeneChip microarray technique. Pharmacokinetic parameters were estimated from plasma concentrations of paroxetine for more than 240 hours after the oral dose. RESULTS: The oral clearance and area under the plasma concentration versus time curve (AUC) of paroxetine were best described by a nonlinear relationship with metoprolol MR at correlation coefficients of 0.82 and 0.91, respectively (P < .05). Nine extensive metabolizer who were either homozygous or heterozygous for CYP2D6*10B had significantly lower oral clearance values of paroxetine than six extensive metabolizers with CYP2D6*1/*1. The AUC of paroxetine in subjects who were homozygous for CYP2D6*10B (666.4 +/- 169.4 ng/mL x h) was significantly greater than that of subjects who were homozygous for the wild type (194.5 +/- 55.9 ng/mL x h). Unexpectedly, the average AUC of subjects who were heterozygous for CYP2D6*10B was greater with wide variation (789.8 +/- 816.9 ng/mL x h) than that of subjects who were homozygous CYP2D6*10B/*10B mainly because of two atypical subjects whose metoprolol MR was not associated with the CYP2D6*10B genotype and who showed greater AUC and lower oral clearance than subjects with homozygous CYP2D6*10B. CONCLUSIONS: The CYP2D6 activity measured by metoprolol MR was a strong predictor of paroxetine disposition in Korean extensive metabolizers. In general, the extensive metabolizers with the CYP2D6*10B allele seemed to have higher plasma concentrations of paroxetine than extensive metabolizers with the wild-type CYP2D6 genotype. However, quantitative prediction of paroxetine disposition from the CYP2D6*10B genotype alone was not perfect because several Korean extensive metabolizers had metoprolol MRs that were not associated with the genotype.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10824636&dopt=Abstract
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camh.net
BACKGROUND: Recent reports suggest that adverse effects on sexual function occur in up to 50% of patients who are treated with selective serotonin reuptake inhibitor (SSRI) antidepressants. Previously cited low rates were more likely a function of underreporting than underoccurrence. There is less evidence about rates of dysfunction with serotonin-norepinephrine reuptake inhibitor (SNRI) and reversible inhibitor of monoamine oxidase A (RIMA) antidepressants. The purpose of this report is to evaluate disturbances in sexual drive/desire and arousal/orgasm in 107 patients who met criteria for major depressive disorder and received treatment with either moclobemide, paroxetine, sertraline, or venlafaxine. METHOD: All consenting eligible patients who met DSM-IV criteria for major depressive disorder completed the Sexual Functioning Questionnaire, version 1 (SFQ) and were assessed using the 17-item Hamilton Rating Scale for Depression (HAM-D) prior to and after 8 or 14 weeks of antidepressant therapy. Analyses were carried out to examine the effect of gender, drug type, pretreatment level of sexual dysfunction, and drug response on reported sexual dysfunction. RESULTS: Compared with women, men experienced a significantly greater level of drug-related impairment in drive/desire (p < .05), whereas there were no statistically significant differences in levels of arousal/orgasm impairment between men and women. The reported impairment in drive/desire items for men ranged from 38% to 50% and from 26% to 32% for women. No differences were found across the 4 antidepressants in men, whereas in women, rates of dysfunction were generally higher with sertraline and paroxetine, but only significantly so in comparison with moclobemide on some measures (p < .03). Rates of sexual dysfunction with venlafaxine tended to fall between those of SSRIs and the RIMA agent. An unexpected relationship was found between favorable drug response and a decreased level of drug-induced sexual dysfunction. CONCLUSION: Antidepressant-induced sexual dysfunction occurs in approximately 30% to 70% of patients who are treated with sertraline or paroxetine. Lower rates are reported with moclobemide and venlafaxine. Clinicians should evaluate the various aspects of sexual dysfunction before and during antidepressant therapy.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10830148&dopt=Abstract
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Br J Pharmacol. 1999 Feb;126(3):568-71.
Modulation of noradrenergic neuronal firing by selective serotonin reuptake blockers.
Szabo ST, de Montigny C, Blier P.
Neurobiological Psychiatry Unit, McGill University, Montreal, Canada.
Using in vivo extracellular unitary recording, the effect of short term (2-day) and long-term (21-day) administration of the selective 5-HT reuptake inhibitor (SSRI) paroxetine (10 mg kg(-1) day(-1), s.c. using osmotic minipumps) was examined on the spontaneous firing activity of locus coeruleus noradrenergic neurons. Long-term but not short-term treatment significantly decreased firing activity. Thus, it appears that enhancing 5-HT neurotransmission by sustained SSRI administration leads to a reduction of the firing rate of noradrenergic neurons. The SSRI paroxetine therefore alters the activity of noradrenergic neurons with a delay that is consistent with its therapeutic action in depression and panic disorder.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10188964&dopt=Abstract
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