Drugs online research references
J Clin Pharmacol. 1989 Aug;29(8):746-7.
Nonlinear kinetics of trimipramine in depressed patients.
Musa MN.
Department of Psychiatry, Chicago Medical School, IL 60064.
An increase of the dose of trimipramine (TM) results in a markedly disproportionate increase of the steady-state plasma concentration of the major active metabolite desmethyltrimipramine (DMT). Ten patients receiving 75 mg/day of TM had a mean steady-state plasma concentration of 53.8 ng/ml TM and 26.3 ng/ml DMT. Ten others receiving 150 ng/ml TM had a mean concentration of 122.5 ng/ml TM and 133.8 ng/ml DMT. This is most likely due to the saturation within therapeutic dosage range of the subspecies of cytochrome P-450 responsible for hydroxylation of DMT. Available data on metabolism of tricyclic antidepressants shows that the hydroxylation of desmethylimipramine (desipramine) but not that of desmethylamitriptyline (nortriptyline) reaches saturation within therapeutic dosage range. Clinicians should take into consideration the possibility of dose-dependent kinetics when adjusting the dose of tricyclic antidepressants. This finding highlights the value of monitoring of blood levels of antidepressants.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2778096&dopt=Abstract
Clin Chem. 1977 Jul;23(7):1326-8.
Therapeutic monitoring of tricyclic antidepressants in plasma by gas chromatography.
Dorrity F Jr, Linnoila M, Habig RL.
We describe a comprehensive gas chromatographic analysis for therapeutic concentrations of amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and desmethyldoxepin in plasma, with use of a nitrogen detector. All these drugs are extracted and chromatographed under identical conditions. Each tertiary amine tricyclic is well resolved from its secondary amine metabolite on a mixed-phase column and the concentrations of both are determined simultaneously, without derivatization. The lower limit of sensitivity is 10 microgram/liter of plasma (2-ml sample). Analytical recoveries of the tertiary and secondary amines are 100 and 80%, respectively. Between-run CV's for all of the drugs ranged between 5 and 7%.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=872381&dopt=Abstract
DICP. 1991 Dec;25(12):1368-73.
Early individualization of tricyclic antidepressant dosing using a Bayesian pharmacokinetic model.
Kehoe WA, Harralson AF, Kwentus JA, Jacisin JJ, Sheffel WB, Hetnal MJ.
School of Pharmacy, University of the Pacific, Stockton, CA 95211.
Existing methods to prospectively dose tricyclic antidepressants (TCAs) require either specific test doses, precisely timed serum sampling, or both. We prospectively tested a new pharmacokinetic model that allows flexible dosing and sampling to determine maintenance requirements in patients receiving TCAs. Thirty-four patients entered the study. Drug concentrations were measured on the third day after starting TCA therapy. These values were analyzed using a Bayesian pharmacokinetic model to determine drug clearance and volume of distribution. This information was then used to predict the serum concentration resulting from a maintenance dose chosen by the psychiatrist. In phase I (n = 17), patients received imipramine without specific starting doses. Phase II (n = 17) was performed to provide a preliminary evaluation of the method in the usual clinical environment. In this phase, patients received either amitriptyline, imipramine, desipramine, doxepin (75 mg on day 1,100 mg on day 2), or nortriptyline (50 mg on day 1, 75 mg on day 2). Lower doses were allowed if clinically indicated. The predictability of future serum concentrations was then compared between the two phases. The mean prediction errors (model bias) in phases I and II were -15.5 +/- 27.3 and -12.3 +/- 21.8 ng/mL and were not different (p greater than 0.05). The absolute prediction errors (model precision) were 18.5 +/- 25.1 and 18.8 +/- 16.0 ng/mL and were not different (p greater than 0.05). Two slow metabolizers were identified (clearance less than 0.10 L/kg/h). This new method allows the determination of maintenance dose requirements early in therapy without standard test doses or specifically timed serum sampling.(ABSTRACT TRUNCATED AT 250 WORDS)
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1815435&dopt=Abstract
Herbs and Pharmaceuticals Online ||
Hair Million herbal formula for hair loss and hair growth ||
Wellstreet online pharmacy for click-order prescription medications ||
Altace Online Pharmacy ||
Rx Drugs USA, Prescription Drugs Online Pharmacy ||
Insurance plans and information ||
Insurance policies for all purposes ||
Antibiotics and prescription medications online literature ||