Publications by authors named "Martin Dowty"

Physiologically-based pharmacokinetic (PBPK) modeling offers a viable approach to predict induction drug-drug interactions (DDIs) with the potential to streamline or reduce clinical trial burden if predictions can be made with sufficient confidence. In the current work, the ability to predict the effect of rifampin, a well-characterized strong CYP3A4 inducer, on 20 CYP3A probes with publicly available PBPK models (often developed using a workflow with optimization following a strong inhibitor DDI study to gain confidence in fraction metabolized by CYP3A4, f, and fraction available after intestinal metabolism, Fg), was assessed. Substrates with a range of f (0.

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Abrocitinib is a selective Janus kinase 1 inhibitor approved for the treatment of atopic dermatitis. It is metabolized primarily by cytochrome P450 (CYP) 2C19 (approximately 53%) and CYP2C9 (approximately 30%), which form 2 active metabolites. The pharmacologic activity of abrocitinib is attributable to the unbound exposures of abrocitinib and those metabolites with active moiety area under the plasma concentration-time curve (AUC) considered the best measure of the total pharmacological effect.

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  • - Ritlecitinib is an oral medication being developed for treating moderate-to-severe alopecia areata, functioning as an irreversible inhibitor of specific kinases.
  • - A study using advanced mass spectroscopy explored how ritlecitinib is absorbed, distributed, metabolized, and eliminated in the body, revealing key pharmacokinetic parameters like a clearance rate of 43.7 L/h and a bioavailability of 64%.
  • - The research found that ritlecitinib binds to plasma proteins and is mainly cleared through urine, with metabolic processes involving various cytochrome P450 enzymes and glutathione-related conjugation playing significant roles.
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  • * To gain regulatory approval for the MR microsphere, researchers needed to establish bioequivalence (BE) with the IR solution, which was achieved by conducting physiologically-based pharmacokinetic (PBPK) virtual BE trials instead of traditional clinical ones.
  • * The trials showed that the MR microsphere (10 mg once daily) is bioequivalent to the IR solution (5 mg twice daily) after both a single and multiple doses, highlighting a new method that minimizes unnecessary testing on healthy volunteers while aiding in drug formulation development.
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Brepocitinib is an oral once-daily Janus kinase 1 and Tyrosine kinase 2 selective inhibitor currently in development for the treatment of several autoimmune disorders. Mass balance and metabolic profiles were determined using accelerator mass spectrometry in six healthy male participants following a single oral 60 mg dose of C-brepocitinib (∼300 nCi). The average mass balance recovery was 96.

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Background And Objective: Abrocitinib is an oral small-molecule Janus kinase (JAK)-1 inhibitor approved for the treatment of moderate-to-severe atopic dermatitis. In vitro studies indicated that abrocitinib is a weak time-dependent inhibitor of cytochrome P450 (CYP) 2C19/3A and a weak inducer of CYP1A2/2B6/2C19/3A. To assess the potential effect of abrocitinib on concomitant medications, drug-drug interaction (DDI) studies were conducted for abrocitinib with sensitive probe substrates of these CYP enzymes.

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  • * Due to the dissolution differences between 100-mg and 50-mg capsules, a biowaiver for the lower dose couldn't be granted based solely on traditional tests.
  • * A physiologically based pharmacokinetic (PBPK) model was used to predict in vivo behavior from in vitro data, showing that 50-mg capsules are likely bioequivalent to 100-mg capsules with over a 90% success probability in virtual trials.
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  • Ritlecitinib, an investigational drug targeting certain kinases, was studied for its effects on drug transporters and potential interactions with other medications.
  • In both in vitro and clinical studies, ritlecitinib was assessed for its ability to inhibit various transporters, including BCRP, OATP1B1, and OAT3, using rosuvastatin as a test drug and measuring endogenous biomarkers.
  • Results indicated that ritlecitinib does not inhibit these transporters, suggesting limited potential for clinically significant drug interactions, and supports the use of coproporphyrin I and pyridoxic acid as biomarkers for evaluating transporter activity.
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Aims: Brepocitinib is a tyrosine kinase 2/Janus kinase 1 inhibitor being investigated for the treatment of several autoimmune diseases. This study assessed the absorption, distribution, metabolism and excretion of oral brepocitinib, and the absolute oral bioavailability (F) and fraction absorbed (F ) using a C microtracer approach.

Methods: This was a phase 1 open-label, nonrandomized, fixed sequence, two-period, single-dose study of brepocitinib in healthy male participants.

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  • Ritlecitinib is being developed as a treatment for inflammatory diseases and inhibits certain transport proteins such as OCT1.
  • A clinical study showed that when ritlecitinib is taken with sumatriptan (a drug that relies on OCT1), its concentration in the bloodstream increased significantly, indicating that ritlecitinib affects OCT1’s function.
  • The study confirmed that while ritlecitinib and its metabolite M2 inhibit OCT1, they do not have a meaningful impact on other transporters like OCT2 or MATE1/2K.
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Brepocitinib is a tyrosine kinase 2 and Janus kinase 1 inhibitor in development for treatment of inflammatory autoimmune diseases. This analysis aimed to add to the pharmacokinetic knowledge of the medication, through development of a population pharmacokinetic model and identification of factors that affect drug disposition. Plasma samples from 5 clinical trials were collated, composed of healthy volunteers, patients with psoriasis and patients with alopecia areata taking oral brepocitinib.

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Abrocitinib is an oral once-daily Janus kinase 1 selective inhibitor being developed for the treatment of moderate-to-severe atopic dermatitis. This study examined the disposition of abrocitinib in male participants following oral and intravenous administration using accelerator mass spectroscopy methodology to estimate pharmacokinetic parameters and characterize metabolite (M) profiles. The results indicated abrocitinib had a systemic clearance of 64.

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Zimlovisertib (PF-06650833) is a selective, reversible inhibitor of interleukin-1 receptor-associated kinase 4 (IRAK4) with anti-inflammatory effects. This phase 1, open-label, fixed-sequence, two-period, single-dose study aimed to evaluate the mass balance and excretion rate of zimlovisertib in healthy male participants using a C-microtracer approach. All six participants received 300 mg C-zimlovisertib with lower radioactivity per mass unit orally in Period A, then unlabeled zimlovisertib 300 mg orally and C-zimlovisertib 135 μg intravenously (IV) in Period B.

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Abrocitinib is an oral Janus kinase 1 (JAK1) inhibitor currently approved in the United Kingdom for the treatment of moderate-to-severe atopic dermatitis (AD). As patients with AD may use medications to manage comorbidities, abrocitinib could be used concomitantly with hepatic and/or renal transporter substrates. Therefore, we assessed the potential effect of abrocitinib on probe drugs and endogenous biomarker substrates for the drug transporters of interest.

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Background And Objective: Abrocitinib is a Janus kinase 1-selective inhibitor for the treatment of moderate-to-severe atopic dermatitis. Abrocitinib is eliminated primarily by metabolism involving cytochrome P450 (CYP) enzymes. Abrocitinib pharmacologic activity is attributable to the unbound concentrations of the parent molecule and 2 active metabolites, which are substrates of organic anion transporter 3 (OAT3).

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  • Janus kinase (JAK) inhibitors, specifically ritlecitinib and brepocitinib, are being studied for treating alopecia areata (AA) with promising results from early research.
  • In a phase 2a clinical trial, biopsy samples from 46 patients showed significant improvements in scalp biomarkers after 24 weeks, correlating with hair regrowth measured by the Severity of Alopecia Tool (SALT) score.
  • While brepocitinib showed better results at week 12, ritlecitinib outperformed it by week 24, suggesting the need for larger and longer-term trials to confirm these findings.
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  • * They compiled case studies and recent literature to demonstrate how PBPK models effectively predict drug-drug interactions related to CYP3A induction.
  • * The group aims to improve the application of PBPK modeling in drug development by proposing workflows, discussing future directions, and identifying existing gaps to optimize the use of new drugs affected by CYP3A.
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Abrocitinib, an oral once-daily Janus kinase 1 selective inhibitor, is under development for the treatment of atopic dermatitis. This phase 1, nonrandomized, open-label, single-dose study (NCT03660241) investigated the effect of renal impairment on the pharmacokinetics, safety, and tolerability of abrocitinib and its metabolites following a 200-mg oral dose. Twenty-three subjects with varying degrees of renal function (normal, moderate, and severe impairment) were enrolled.

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  • Abrocitinib is a once-daily oral medication being studied for the treatment of atopic dermatitis and its safety in patients with various levels of liver impairment.
  • In a phase 1 study involving 24 participants with normal, mild, and moderate hepatic function, researchers found that hepatic impairment did not significantly affect the pharmacokinetics (how the drug is processed in the body) or safety of abrocitinib.
  • The study concluded that abrocitinib can be used safely without dose adjustments for patients with mild or moderate liver issues.
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  • A novel inhibitor of tyrosine kinase 2 (TYK2), PF-06826647, shows potential for treating inflammatory conditions by targeting pro-inflammatory cytokine signaling.
  • In the first-in-human study involving 69 healthy participants, researchers examined its safety, tolerability, and how the drug is processed in the body (pharmacokinetics) during both single and multiple ascending dose periods.
  • Results indicated that PF-06826647 had a good safety profile, with no serious adverse events and mild side effects, making it suitable for further testing in patients.
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Tyrosine kinase 2 (TYK2) is a member of the JAK kinase family that regulates signal transduction downstream of receptors for the IL-23/IL-12 pathways and type I interferon family, where it pairs with JAK2 or JAK1, respectively. On the basis of human genetic and emerging clinical data, a selective TYK2 inhibitor provides an opportunity to treat autoimmune diseases delivering a potentially differentiated clinical profile compared to currently approved JAK inhibitors. The discovery of an ATP-competitive pyrazolopyrazinyl series of TYK2 inhibitors was accomplished through computational and structurally enabled design starting from a known kinase hinge binding motif.

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Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis. It is eliminated via multiple pathways including oxidative metabolism (∼70%) and renal excretion (29%). This study aimed to predict the impact of drug-drug interactions and renal or hepatic impairment on tofacitinib pharmacokinetics using a physiologically based pharmacokinetic (PBPK) model.

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Translation of modulation of drug target activity to therapeutic effect is a critical aspect for all drug discovery programs. In this work we describe the profiling of a non-receptor tyrosine-protein kinase (TYK2) inhibitor which shows a functionally relevant potency shift between human and preclinical species (e.g.

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