Late-occurring and Long-circulating Metabolites of GABAAα2,3 Receptor Modulator AZD7325 Involving Metabolic Cyclization and Aromatization: Relevance to MIST Analysis and Application for Patient Compliance.

AZD7325 [4-amino-8-(2-fluoro-6-methoxyphenyl)-N-propylcinnoline-3-carboxamide] is a selective GABAAα2,3 receptor modulator intended for the treatment of anxiety disorders through oral administration. An interesting metabolic cyclization and aromatization pathway led to the tricyclic core of M9, i.e., 2-ethyl-7-(2-fluoro-6-methoxyphenyl)pyrimido[5,4-c]cinnolin-4(3H)-one. Further oxidative metabolism generated M10 via O-demethylation and M42 via hydroxylation. An authentic standard of M9 was synthesized to confirm the novel structure of M9 and that of M10 and M42 by liver microsomal incubation of the M9 standard. Metabolites M9, M10, and M42 were either minor or absent in plasma samples after a single dose; however, all became major metabolites in human and preclinical animal plasma after repeated doses and circulated in humans longer than 48 hours after the end of seven repeated doses. The absence of these long circulating metabolites from selected patients' plasma samples was used to demonstrate patient noncompliance as the cause of unexpected lack of drug exposure in some patients during a Phase IIb outpatient clinical study. The observation of late-occurring and long-circulating metabolites demonstrates the need to collect plasma samples at steady state after repeated doses when conducting metabolite analysis for the safety testing of drug metabolites. All 12 major nonconjugate metabolites of AZD7325 observed in human plasma at steady state were also observed in dog, rat, and mouse plasma samples collected from 3-month safety studies and at higher exposures in the animals than humans. This eliminated concern about human specific or disproportional metabolites.

An open-label, non-randomised, phase 1, single-dose study to assess the pharmacokinetics of ceftaroline in patients with end-stage renal disease requiring intermittent haemodialysis.

For patients with normal renal function, the recommended ceftaroline fosamil dose is a 600 mg 1-h intravenous (i.v.) infusion every 12 h (q12h). In patients with a creatinine clearance of ≤30 mL/min, including those with end-stage renal disease (ESRD), the recommended dose is a 200 mg 1-h i.v. infusion q12h. This phase 1 study (NCT01664065) evaluated the pharmacokinetics, safety and tolerability of ceftaroline fosamil 200 mg 1-h i.v. infusion in patients with ESRD. Patients with ESRD (n=8) participated in two treatment periods (ceftaroline fosamil 200 mg administered pre- and post-haemodialysis) separated by >1 week. Healthy volunteers (n=7) received a single 600 mg dose of ceftaroline fosamil. Blood (pre- and post-haemodialysis) and dialysate samples were obtained for pharmacokinetic analysis. In patients with ESRD, the geometric mean [coefficient of variation (%CV)] plasma ceftaroline area under the plasma concentration-time curve from zero to infinity (AUC0-∞) following post-haemodialysis ceftaroline fosamil 200 mg infusion was 64.8 (38.9)µg·h/mL, similar to that in volunteers following a 600 mg infusion [62.7 (9.4)µg·h/mL]. Ceftaroline AUC0-∞ decreased by ca. 50% when infusion was initiated pre-haemodialysis. In the pre-haemodialysis treatment period, 80% of the ceftaroline fosamil dose was recovered in dialysate as ceftaroline (73%) and ceftaroline M-1 (7%). The frequency of adverse events was similar across patients with ESRD (pre- and post-haemodialysis) and volunteers (43%, 50% and 43% of subjects, respectively). Ceftaroline fosamil 200 mg 1-h i.v. infusion q12h, administered post-haemodialysis on dialysis days, is an appropriate dosage regimen for ESRD patients.

Evaluation of the pharmacokinetics and safety of single and multiple ceftaroline fosamil infusions in healthy Chinese and Western subjects.

OBJECTIVES: Two phase I studies in healthy Chinese (NCT01458743) and Western (NCT01612507) subjects evaluated the pharmacokinetics (PK) and safety of single and multiple ceftaroline fosamil 600 mg infusions administered every 8 or 12 hours (q8h or q12h). METHODS: Each study enrolled subjects sequentially into 1 of 2 cohorts (cohort 1: 60-minute infusions; cohort 2: 120-minute infusions). All subjects in the Chinese (n = 26) study received open label ceftaroline fosamil; in the Western study, subjects (n = 41) in each cohort were randomized 3 : 1 to ceftaroline fosamil or placebo infusions. Single infusions were administered on days 1 and 8. On days 2 - 7 (3 - 7 for Chinese study, cohort 1) subjects received q12h or q8h infusions. Plasma and urine were collected on days 1 and 8 for PK analysis. RESULTS: Ceftaroline PK was linear and time-independent following single and multiple doses of ceftaroline fosamil. The magnitude and timing of peak plasma concentrations of ceftaroline (active metabolite), ceftaroline fosamil (prodrug), and ceftaroline M-1 (inactive metabolite) varied according to the ceftaroline fosamil dosing schedule (q12h or q8h) and infusion duration (60 minutes or 120 minutes), but overall plasma ceftaroline exposures within the respective dosing intervals were broadly similar across cohorts. The most frequent adverse events were rash/drug eruption, most of which were of mild-moderate intensity and considered related to treatment. CONCLUSIONS: Ceftaroline PK was broadly similar in healthy Chinese and Western subjects receiving equivalent dose regimens. The tolerability profile of ceftaroline fosamil in Chinese and Western subjects was consistent with previous clinical trials.

Safety, local tolerability and pharmacokinetics of ceftaroline fosamil administered in a reduced infusion volume.

AIMS: The standard dose of ceftaroline fosamil for patients with normal renal function is 600 mg diluted in 250 ml by 60 min intravenous infusion every 12 h. This two part phase I trial (NCT01577589) assessed safety and local tolerability of multiple ceftaroline fosamil 50 ml and 250 ml infusions, and pharmacokinetics following single administrations of each infusion volume. METHODS: Part A was a placebo-controlled, double-blind, multiple dose crossover study. Twenty-four healthy subjects were randomized to simultaneous, bilateral ceftaroline fosamil 600 mg and placebo infusions in each arm (50 ml then 250 ml or vice versa) every 12 h for 72 h, with a ≥ 4.5 day washout. Local tolerability was evaluated by the Visual Infusion Phlebitis scale, with scores ≥2 considered infusion site reactions (ISRs). Part B was an open label crossover study. Ten subjects were randomized to single 50 ml and 250 ml ceftaroline fosamil 600 mg infusions on days 1 and 3 (washout on day 2). Blood samples for pharmacokinetic analysis were taken over 24 h. RESULTS: In part A, four subjects (16.7%) experienced ISRs, all of which were associated with placebo infusions. No ISRs were reported for either ceftaroline fosamil 50 ml or 250 ml. Plasma pharmacokinetics (ceftaroline fosamil, active ceftaroline and an inactive metabolite) were similar following single 50 ml and 250 ml infusions in part B. CONCLUSIONS: No new safety concerns were identified for ceftaroline fosamil 600 mg 50 ml compared with 250 ml. These findings suggest infusion volumes down to 50 ml may be used in patients with fluid intake restrictions.

A clinical study to assess CYP1A2 and CYP3A4 induction by AZD7325, a selective GABA(A) receptor modulator - an in vitro and in vivo comparison.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: • AZD7325 is an orally administered, potent, selective gamma-amino-butyric acid (GABA(A) ) α2,3 receptor modulator intended for the treatment of anxiety. • The induction effects of AZD7325 on CYP1A2 and CYP3A4 have not been systematically studied. WHAT THIS STUDY ADDS: • The in vitro studies showed that AZD7325 was a moderate CYP1A2 inducer and potent CYP3A4 inducer. • The follow-up clinical studies in healthy volunteers demonstrated that the expected efficacious daily dose of AZD7325 only weakly induced the pharmacokinetics of the CYP3A4 sensitive substrate, midazolam, and had no effect on the pharmacokinetics of the CYP1A2 substrate, caffeine. There was no apparent change in AZD7325 exposure following co-administration of midazolam or caffeine compared with AZD7325 alone. • The study demonstrated that clinical exposure of the inducer plays a critical role in the determination of cytochrome P450 induction risk of a drug candidate. AIM(S): To investigate the potential of AZD7325 to induce CYP1A2 and CYP3A4 enzyme activities. METHODS: Induction of CYP1A2 and CYP3A4 by AZD7325 was first evaluated using cultured human hepatocytes. The effect of multiple doses of 10 mg AZD7325 on the pharmacokinetics of midazolam and caffeine was then examined in healthy subjects. RESULTS: The highest CYP1A2 and CYP3A4 induction responses were observed in human hepatocytes treated with 1 or 10 µm of AZD7325, in the range of 17.9%-54.9% and 76.9%-85.7% of the positive control responses, respectively. The results triggered the further clinical evaluation of AZD7325 induction potential. AZD7325 reached a plasma C(max) of 0.2 µm after 10 mg daily dosing to steady-state. AZD7325 decreased midazolam geometric mean AUC by 19% (0.81-fold, 90% CI 0.77, 0.87), but had no effect on midazolam C(max) (90% CI 0.82, 0.97). The mean CL/F of midazolam increased from 62 l h(-1) (midazolam alone) to 76 l h(-1) when co-administered with AZD7325. The AUC and C(max) of caffeine were not changed after co-administration of AZD7325, with geometric mean ratios (90% CI) of 1.17 (1.12, 1.23) and 0.99 (0.95, 1.03), respectively. CONCLUSIONS: While AZD7325 appeared to be a potent CYP3A4 inducer and a moderate CYP1A2 inducer from in vitro studies, the expected efficacious dose of AZD7325 had no effect on CYP1A2 activity and only a weak inducing effect on CYP3A4 activity. This comparison of in vitro and in vivo results demonstrates the critical role that clinical exposure plays in evaluating the CYP induction risk of a drug candidate.