Escitalopram is the (S)-enantiomer of the racemic selective serotonin reuptake inhibitor antidepressant citalopram. Clinical studies have shown that escitalopram is effective and well tolerated in the treatment of depression and anxiety disorders. Following oral administration, escitalopram is rapidly absorbed and reaches maximum plasma concentrations in approximately 3-4 hours after either single- or multiple-dose administration. The absorption of escitalopram is not affected by food. The elimination half-life of escitalopram is about 27-33 hours and is consistent with once-daily administration. Steady-state concentrations are achieved within 7-10 days of administration. Escitalopram has low protein binding (56%) and is not likely to cause interactions with highly protein-bound drugs. It is widely distributed throughout tissues, with an apparent volume of distribution during the terminal phase after oral administration (V(z)/F) of about 1100L. Unmetabolised escitalopram is the major compound in plasma. S-demethylcitalopram (S-DCT), the principal metabolite, is present at approximately one-third the level of escitalopram; however, S-DCT is a weak inhibitor of serotonin reuptake and does not contribute appreciably to the therapeutic activity of escitalopram. The didemethyl metabolite of escitalopram (S-DDCT) is typically present at or below quantifiable concentrations. Escitalopram and S-DCT exhibit linear and dose-proportional pharmacokinetics following single or multiple doses in the 10-30 mg/day dose range. Adolescents, elderly individuals and patients with hepatic impairment do not have clinically relevant differences in pharmacokinetics compared with healthy young adults, implying that adjustment of the dosage is not necessary in these patient groups. Escitalopram is metabolised by the cytochrome P450 (CYP) isoenzymes CYP2C19, CYP2D6 and CYP3A4. However, ritonavir, a potent inhibitor of CYP3A4, does not affect the pharmacokinetics of escitalopram. Coadministration of escitalopram 20mg following steady-state administration of cimetidine or omeprazole led to a 72% and 51% increase, respectively, in escitalopram exposure compared with administration alone. These changes were not considered clinically relevant. In vitro studies have shown that escitalopram has negligible inhibitory effects on CYP isoenzymes and P-glycoprotein, suggesting that escitalopram is unlikely to cause clinically significant drug-drug interactions. The favourable pharmacokinetic profile of escitalopram suggests clinical utility in a broad range of patients.

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The pharmacokinetics of escitalopram (S-citalopram) and its principal metabolite, S-demethylcitalopram (S-DCT), were investigated after intravenous and oral administration to healthy subjects. After intravenous infusion of escitalopram, the mean systemic clearance and volume of distribution were 31 L/h and 1,100 L, respectively. After oral administration of single or multiple doses, the absorption was relatively fast, with the maximum observed plasma or serum concentration (C(max)) attained after 3 to 4 hours. The mean half-lives were 27 and 33 hours, respectively; steady state was attained within 10 days. The area under the plasma or serum concentration time curve from time zero to 24 hours and C(max) was both linear and proportional to the dose. The apparent volume of distribution was around 20 L/kg. Comparison of the systemic and oral clearance implied a high absolute bioavailability. There was no evidence of interconversion from S-citalopram to R-citalopram either in plasma or in urine. Concurrent intake of food had no effect on the pharmacokinetics of escitalopram or its metabolite. All treatments were well tolerated.

SummaryBackground ASN002 is an oral dual inhibitor of Janus kinase and spleen tyrosine kinase, which are involved in the pathogenesis of atopic dermatitis (AD) through their regulatory role on T helper (Th)1, Th2 and Th17/Th22 pathways.ObjectivesThe objectives of this study were to evaluate the efficacy, safety, pharmacokinetics and effects on systemic biomarkers of ASN002 in patients with moderate‐to‐severe AD. Methods A total of 36 patients with moderate‐to‐severe AD were randomized (3 : 1) to ASN002 or placebo in the phase Ib study. Three dosage cohorts were studied over a 28‑day period (20 mg, 40 mg and 80 mg once daily).Results ASN002 was superior to placebo for the proportion of patients achieving Eczema Area and Severity Index (EASI) 50 (20 mg 20%, P = 0·93; 40 mg 100%, P = 0·003; 80 mg 83%, P = 0·03; placebo 22%), EASI 75 (20 mg 0%, P = 0·27; 40 mg 71%, P = 0·06; 80 mg 33%, P = 0·65; placebo 22%) and in change from baseline in pruritus (20 mg −1·3 ± 2·1, P = 0·81; 40 mg −3·1 ± 2·7, P = 0·27; 80 mg −4·7 ± 2·1, P = 0·01; placebo −1·6 ± 1·8). Adverse events were generally mild and similar across all groups. ASN002 showed dose‐dependent plasma exposure with low interpatient variability, significantly downregulated several serum biomarkers involved in Th1, Th2 and Th17/Th22 immunity, and decreased the atherosclerosis‐associated biomarker E selectin/SELE.ConclusionsIn patients with moderate‐to‐severe AD, ASN002 showed strong efficacy with rapid onset of action and associated improvements in systemic inflammation.

Background: Moderate-to-severe atopic dermatitis (AD) has been associated with significant disease burden and systemic abnormalities and often requires systemic treatments. Currently, safe and effective oral systemic treatments for moderate-to-severe AD are not yet available. ASN002 is an oral inhibitor of the Janus kinase/spleen tyrosine kinase signaling pathways, targeting several cytokine axes (T H 2/T H 22/T H 17/T H 1) and epidermal differentiation. Objective: We sought to evaluate the effect of ASN002 on the cellular and molecular biomarker profile of patients with moderate-to-severe AD and to correlate changes in biomarkers to improvements in clinical severity measures and pruritus. Methods: Thirty-six patients with moderate-to-severe AD were randomized to groups with dose escalation of ASN002 (20, 40, and 80 mg) and a placebo group. Skin biopsy specimens were performed at baseline, day 15, and day 29. Gene expression studies were conducted by using microarray and quantitative RT-PCR, and cellular infiltrates and protein expression were studied by using immunohistochemistry. Results: ASN002 reversed the lesional skin transcriptome toward a nonlesional phenotype. It also rapidly and significantly suppressed key inflammatory pathways implicated in AD pathogenesis, including T H 2 (IL4 receptor [IL4R], IL13, CCL13/ monocyte chemoattractant protein 4, CCL17/thymus and activation-regulated chemokine, CCL18/pulmonary and activation-regulated chemokine, CCL22/macrophage-derived chemokine, and CCL26/eotaxin-3), T H 17/T H 22 (lipocalins, PI3/ elafin, CCL20, S100A7/S100A8/S100A9, and IL36G/IL36RN), and T H 1 (IFNG, CXCL9/CXCL11, and MX1) axes and barrierrelated measures (filaggrin [FLG] and CLDN23). Significant improvements in AD gene signatures were observed predominantly in the 40-and 80-mg groups. Smaller and largely nonsignificant molecular changes were seen in the 20-mg and placebo groups. Conclusion: The Janus kinase/spleen tyrosine kinase inhibitor ASN002 significantly suppressed key AD inflammatory pathways, corresponding to clinical response. ASN002 might be an effective novel therapeutic agent for moderate-to-severe AD.