Modification of the association between paroxetine serum concentration and SERT-occupancy by ABCB1 (P-glycoprotein) polymorphisms in major depressive disorder

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) exert substantial variability in effectiveness in patients with major depressive disorder (MDD), with up to 50-60% not achieving adequate response. Elucidating pharmacokinetic factors that explain this variability is important to increase treatment effectiveness. OBJECTIVES: To examine potential modification of the relationship between paroxetine serum concentration (PSC) and serotonin transporter (SERT)-occupancy by single nucleotide polymorphisms (SNPs) of the ABCB1 gene, coding for the P-glycoprotein (P-gp) pump, in MDD patients. To investigate the relationship between ABCB1 SNPs and clinical response. METHODS: Patients had MDD and received paroxetine 20 mg/day. We measured PSC after 6 weeks. We quantified SERT-occupancy with SPECT imaging (n = 38) and measured 17-item Hamilton Depression Rating Scale (HDRS17)-scores at baseline and after 6 wee

Polymorphisms in type 2 deiodinase are not associated with well-being, neurocognitive functioning, and preference for combined thyroxine/3,5,3′- triiodothyronine therapy

Introduction: Some patients on levothyroxine replacement display significant impairment in psychological well-being, compared with sex- and age-matched controls. Levothyroxine-treated patients can be assumed to derive T3 exclusively from deiodination of T4, which, in the central nervous system, is regulated by type II deiodinase (DII). Objective: We investigated whether two recently identified polymorphisms in the DII gene (DII-ORFa-Gly3Asp and DII-Thr92Ala) are determinants of well-being and neurocognitive functioning and associated with a preference for replacement with a combination of T3 and T4. Methods: Genotypes for both polymorphisms were determined in 141 patients with primary autoimmune hypothyroidism, adequately treated with levothyroxine monotherapy and participating in a randomized clinical trial comparing T4 therapy with T4/T3 combination therapy. Questionnaires on well-being and neurocognitive tests were performed at baseline. Results: Allele frequencies in patients with primary hypothyroidism were similar to those of healthy blood bank donors (32.0 vs. 33.9% for DII-ORFa-Gly3Asp and 40.4 vs. 38.8% for DII-Thr92Ala). DII polymorphisms were not associated with measures of well-being, neurocognitive functioning, or preference for combined T 4/T3 therapy. Conclusion: The DII-ORFa-Gly3Asp and DII-Thr92Ala polymorphisms do not explain differences in well-being, neurocognitive functioning, or appreciation of T4/T3 combination therapy in patients treated for hypothyroidism. Copyrigh