ObjectiveCONCERTO was a randomised, double-blind, parallel-armed study of methotrexate (MTX) in combination with adalimumab to assess whether an increasing trend of efficacy and decreased safety exists when increasing MTX dose in patients with early rheumatoid arthritis (RA).MethodsEarly, biologic and MTX-naive RA patients (N=395) were evenly randomised to open-label adalimumab (40 mg every other week) plus weekly blinded 2.5, 5, 10 or 20 mg MTX for 26 weeks. Clinical, radiographic and functional outcomes were analysed using two-sided linear trend tests or one-way analysis of covariance.ResultsStatistically significant increasing trends were observed in the proportion of patients achieving the primary endpoint, 28-joint count disease activity score with C reactive protein (DAS28(CRP)) <3.2 (42.9%, 44.0%, 56.6% and 60.2% for 2.5, 5, 10 or 20 mg/week MTX, respectively), DAS28(CRP) <2.6 and American College of Rheumatology 50/70/90 responses with increasing doses of MTX in combination with adalimumab. No statistical differences in minimal clinically important differences in physical function were detected. Statistically significant trends for achieving low disease activity and remission were demonstrated with increasing MTX dose by validated clinical indices; differences comparing 10 and 20 mg MTX were minimal. Adalimumab serum concentrations increased with ascending dose up to 10 mg MTX. More patients experienced infectious adverse events with increasing MTX dose.ConclusionsIncreasing doses of MTX in combination with adalimumab demonstrated a statistically significant trend in improved clinical outcomes that mimicked the adalimumab pharmacokinetic profile. In early RA patients initiating adalimumab combination therapy, efficacy of 10 and 20 mg/week MTX appeared equivalent.

The amount of calcium available for absorption is dependent, in part, on its sustained solubility in the gastrointestinal (GI) tract. Many calcium salts, which are the calcium sources in supplements and food, have pH-dependent solubility and may have limited availability in the small intestine, the major site of absorption. The equilibrium solubility of four calcium salts (calcium oxalate hydrate, calcium citrate tetrahydrate, calcium phosphate, calcium glycerophosphate) were determined at controlled pH values (7.5, 6.0, 4.5 and < or = 3.0) and in distilled water. The solubility of calcium carbonate was also measured at pH 7.5, 6.0 and 4.5 with two CO(2) environments (0.3 and 152 mmHg) above the solution. The precipitation profile of CaCO(3) was calculated using in-vivo data for bicarbonate and pH from literature and equilibrium calculations. As pH increased, the solubility of each calcium salt increased. However, in distilled water each salt produced a different pH, affecting its solubility value. Although calcium citrate does have a higher solubility than CaCO(3) in water, there is little difference when the pH is controlled at pH 7.5. The partial pressure of CO(2) also played a role in calcium carbonate solubility, depressing the solubility at pH 7.5. The calculations of soluble calcium resulted in profiles of available calcium, which agreed with previously published in-vivo data on absorbed calcium. The experimental data illustrate the impact of pH and CO(2) on the solubility of many calcium salts in the presence of bicarbonate secretions in the intestine. Calculated profiles using in-vivo calcium and bicarbonate concentrations demonstrate that large calcium doses may not further increase intestinal calcium absorption once the calcium carbonate solubility product has been reached.

A semiphysiologically based pharmacokinetic (semi-PBPK) model was developed to describe a unique blood, liver, and bile clinical data set for the hepatobiliary imaging agent 99mTechnetium–mebrofenin (99mTc–mebrofenin), and to simulate sites/mechanisms of a 99mTc–mebrofenin–ritonavir drug–drug interaction (DDI). The transport inhibitor ritonavir (multiple-dose: 2 × 300 mg) significantly increased systemic 99mTc–mebrofenin exposure as compared with control (4,464 ± 1,861 vs. 1,970 ± 311 nCi min/ml; mean ± SD), without affecting overall hepatic exposure or biliary recovery. A novel extrahepatic distribution compartment was required to characterize 99mTc–mebrofenin disposition. Ritonavir inhibited 99mTc–mebrofenin accumulation in human sandwich-cultured hepatocytes (SCH) (half maximal inhibitory concentration (IC50) = 3.46 ± 1.53 µmol/l). Despite ritonavir accumulation in hepatocytes, intracellular binding was extensive (97. 6%), which limited interactions with multidrug resistance protein 2 (MRP2)-mediated biliary excretion. These in vitro data supported conclusions from modeling/simulation that ritonavir inhibited 99mTc–mebrofenin hepatic uptake, but not biliary excretion, at clinically relevant concentrations. This integrated approach, utilizing modeling, clinical, and in vitro data, emphasizes the importance of hepatic and extrahepatic distribution, assessment of inhibitory potential in relevant in vitro systems, and intracellular unbound concentrations to assess transporter-mediated hepatic DDIs.

ObjectiveEnthesitis‐related arthritis (ERA) is a juvenile idiopathic arthritis (JIA) category, primarily affecting entheses and peripheral joints. This study evaluated efficacy, safety, and pharmacokinetics of adalimumab versus placebo in patients with ERA.MethodsThis is a phase III, multicenter, randomized double‐blind study in patients ages ≥6 to <18 years with ERA treated with adalimumab (24 mg/m2, maximum dose 40 mg every other week) or placebo for 12 weeks, followed by up to 192 weeks of open‐label adalimumab. The primary end point was percent change from baseline in number of active joints with arthritis (AJC) at week 12. Samples were collected to determine adalimumab serum concentrations. Adverse events (AEs) were assessed throughout the study.ResultsForty‐six patients were randomized (31 adalimumab/15 placebo). At baseline, mean age was 12.9 years, mean duration of ERA symptoms was 2.6 years, mean AJC was 7.8, and mean enthesitis count was 8.1. Mean percent change from baseline in AJC at week 12 was greater in the adalimumab group versus placebo (−62.6% versus −11.6%; P = 0.039). Most secondary variables favored adalimumab versus placebo at week 12. Treatment response further increased with continued adalimumab therapy through week 52. Mean steady‐state adalimumab serum concentrations were 7.5–11.8 μg/ml, similar to patients age ≥2 years with polyarticular JIA. AE rates were similar between placebo and adalimumab: any AE (53.3% versus 67.7%), serious AEs (0% versus 3.2%), and infectious AEs (20.0% versus 29.0%).ConclusionAdalimumab reduced signs and symptoms of ERA at week 12, with improvement sustained through week 52. The safety profile was consistent with previous adalimumab studies.

Results from these three phase I studies supported testing ABT-122 every week and every other week regimens in phase II trials in subjects with rheumatoid and psoriatic arthritis. Study 2 (EudraCT: 2012-003448-54); Study 3 (NCT01853033).