Single- and Multiple-Dose Milnacipran Pharmacokinetics in Healthy Han Chinese Volunteers

Tools for optimising pharmacotherapy in psychiatry (therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests): focus on antidepressants

Objectives: More than 40 drugs are available to treat affective disorders. Individual selection of the optimal drug and dose is required to attain the highest possible efficacy and acceptable tolerability for every patient.Methods: This review, which includes more than 500 articles selected by 30 experts, combines relevant knowledge on studies investigating the pharmacokinetics, pharmacodynamics and pharmacogenetics of 33 antidepressant drugs and of 4 drugs approved for augmentation in cases of insufficient response to antidepressant monotherapy. Such studies typically measure drug concentrations in blood (i.e. therapeutic drug monitoring) and genotype relevant genetic polymorphisms of enzymes, transporters or receptors involved in drug metabolism or mechanism of action. Imaging studies, primarily positron emission tomography that relates drug concentrations in blood and radioligand binding, are considered to quantify target structure occupancy by the antidepressant drugs in vivo. Results: Evidence is given that in vivo imaging, therapeutic drug monitoring and genotyping and/or phenotyping of drug metabolising enzymes should be an integral part in the development of any new antidepressant drug.Conclusions: To guide antidepressant drug therapy in everyday practice, there are multiple indications such as uncertain adherence, polypharmacy, nonresponse and/or adverse reactions under therapeutically recommended doses, where therapeutic drug monitoring and cytochrome P450 genotyping and/or phenotyping should be applied as valid tools of precision medicine.

First-in-human safety, tolerability, and pharmacokinetics of ammoxetine in healthy subjects: a randomized, double-blind, placebo-controlled phase I study

BACKGROUND

Ammoxetine is a novel selective serotonin and norepinephrine reuptake inhibitor. Preclinical studies have indicated the potential utility of ammoxetine for therapy in major depressive disorder.

PURPOSE

To investigate the first-in-human safety, tolerability, and pharmacokinetics (PK) of ammoxetine in healthy subjects and evaluate the effect of CYP2C19 polymorphisms on metabolism of ammoxetine.

METHODS

In this randomized, double-blind, placebo-controlled phase I study, healthy Chinese subjects were allocated to receive 2.5, 7.5, 15, 30, 45, 65, 100 mg ammoxetine or placebo in single-dose part and 15, 30, 45 mg ammoxetine or placebo twice daily for 8 days in multiple-dose part. Pharmacokinetic, safety and tolerability assessments were performed.

RESULTS

A total of 134 subjects were screened and 94 were enrolled. All the ammoxetine-related adverse events (AEs) were mild and resolved spontaneously. No hepatic AEs were reported during the study. Ammoxetine was well absorbed after oral administration with T_max reached in 5.0-6.0 h. After single-dosing, C_max and AUC increased proportionally with dose, except at 65 mg. After multiple-dosing, the exposures of ammoxetine at steady state increased slightly in a more-than-dose-proportional manner over the dose range studied, probably due to the saturated elimination. Steady state was achieved 6 days after multiple-dosing was initiated. The low extent of urinary excretion of ammoxetine (< 2%) indicated it is undergoing extensive metabolism. CYP2C19 polymorphisms had minimal effect on metabolism of ammoxetine.

CONCLUSIONS

Ammoxetine has a favorable pharmacokinetic profile after oral administration and good safety properties. The PK and safety profiles of ammoxetine could enable further clinical development in patients with major depressive disorder.