The Effects of CYP2C19 Genotype on Proxies of SSRI Antidepressant Response in the UK Biobank

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly used psychopharmaceutical treatment for major depressive disorder (MDD), but individual responses to SSRIs vary greatly. CYP2C19 is a key enzyme involved in the metabolism of several drugs, including SSRIs. Variations in the CYP2C19 gene are associated with differential metabolic activity, and thus differential SSRI exposure; accordingly, the CYP2C19 genotype may affect the therapeutic response and clinical outcomes, though existing evidence of this link is not entirely consistent. Therefore, we analysed data from the UK Biobank, a large, deeply phenotyped prospective study, to investigate the effects of CYP2C19 metaboliser phenotypes on several clinical outcomes derived from primary care records, including multiple measures of antidepressant switching, discontinuation, duration, and side effects. In this dataset, 24,729 individuals were prescribed citalopram, 3012 individuals were prescribed escitalopram, and 12,544 individuals were prescribed sertraline. Consistent with pharmacological expectations, CYP2C19 poor metabolisers on escitalopram were more likely to switch antidepressants, have side effects following first prescription, and be on escitalopram for a shorter duration compared to normal metabolisers. CYP2C19 poor and intermediate metabolisers on citalopram also exhibited increased odds of discontinuation and shorter durations relative to normal metabolisers. Generally, no associations were found between metabolic phenotypes and proxies of response to sertraline. Sensitivity analyses in a depression subgroup and metabolic activity scores corroborated results from the primary analysis. In summary, our findings suggest that CYP2C19 genotypes, and thus metabolic phenotypes, may have utility in determining clinical responses to SSRIs, particularly escitalopram and citalopram, though further investigation of such a relationship is warranted.

Enhanced sialylation of the K 562 cell surface membrane glycoconjugates induced by adriamycin

The antitumor agent Adriamycin (ADM) increases the sialic acid content of K 562 cell plasma membrane glycoconjugates. Total and neuraminidase-sensitive sialic acid are enhanced 3 to 4 times when expressed per 10(6) cells. This fact is a consequence of an increase in cell surface and in plasma membrane sialic acid density. Protein-bound and lipid-bound sialic acid are increased in the same way and exhibit the same ratio 90/10. After external radiolabelling by periodide-borotritide and neuraminidase-galactose oxidase-borotritide treatment, only some quantitative changes can be observed. Fractionation of gangliosides by thin layer chromatography gives the same results. Further experiments lead to the following conclusions: the hypersialylation cannot be explained by a G2-block in the cell cycle induced by ADM; it is not a consequence of a differentiation process; it is not observed in a population of adriamycin-resistant K 562 cells and can therefore be considered as a metabolic event linked to the cytotoxic activity of ADM.