Publications

Drug transporters are recognized as key players in the processes of drug absorption, distribution, metabolism, and elimination. The localization of uptake and efflux transporters in organs responsible for drug biotransformation and excretion gives transporter proteins a unique gatekeeper function in controlling drug access to metabolizing enzymes and excretory pathways. This review seeks to discuss the influence intestinal and hepatic drug transporters have on pharmacokinetic parameters, including bioavailability, exposure, clearance, volume of distribution, and half-life, for orally dosed drugs. This review also describes in detail the Biopharmaceutics Drug Disposition Classification System (BDDCS) and explains how many of the effects drug transporters exert on oral drug pharmacokinetic parameters can be predicted by this classification scheme.

BACKGROUND

Idiopathic pulmonary fibrosis is a fatal disease for which no effective treatment exists. We assessed whether treatment with interferon gamma-1b improved survival compared with placebo in patients with idiopathic pulmonary fibrosis and mild-to-moderate impairment of pulmonary function.

METHODS

826 patients with idiopathic pulmonary fibrosis were enrolled from 81 centres in seven European countries, the USA, and Canada. Patients were randomly assigned (double-blind) in a 2:1 ratio to receive 200 microg interferon gamma-1b (n=551) or equivalent placebo (n=275) subcutaneously, three times per week. Eligible patients were aged 40-79 years, had been diagnosed in the past 48 months, had a forced vital capacity of 55-90% of the predicted value, and a haemoglobin-corrected carbon monoxide diffusing capacity of 35-90% of the predicted value. The primary endpoint was overall survival time from randomisation measured at the second interim analysis, when the proportion of deaths had reached 75% of those expected by the study conclusion. This study is registered with ClinicalTrials.gov, number NCT00075998.

FINDINGS

At the second interim analysis, the hazard ratio for mortality in patients on interferon gamma-1b showed absence of minimum benefit compared with placebo (1.15, 95% CI 0.77-1.71, p=0.497), and indicated that the study should be stopped. After a median duration of 64 weeks (IQR 41-84) on treatment, 80 (15%) patients on interferon gamma-1b and 35 (13%) on placebo had died. Almost all patients reported at least one adverse event, and more patients on interferon gamma-1b group had constitutional signs and symptoms (influenza-like illness, fatigue, fever, and chills) than did those on placebo. Occurrence of serious adverse events (eg, pneumonia, respiratory failure) was similar for both treatment groups. Treatment adherence was good and few patients discontinued treatment prematurely in either group.

INTERPRETATION

We cannot recommend treatment with interferon gamma-1b since the drug did not improve survival for patients with idiopathic pulmonary fibrosis, which refutes previous findings from subgroup analyses of survival in studies of patients with mild-to-moderate physiological impairment of pulmonary function.

FUNDING

InterMune.

BACKGROUND & AIMS

Cirrhotic patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) for refractory ascites or recurrent variceal bleeding are at risk for decompensation and death. This study examined whether a new model for end stage liver disease (MELD), which incorporates serum sodium (MELDNa), is a better predictor of death or transplant after TIPS than the original MELD.

METHODS

One hundred forty-eight consecutive patients undergoing nonemergent TIPS for refractory ascites or recurrent variceal bleeding from 1997 to 2006 at a single center were evaluated retrospectively. Cox model analysis was performed with death or transplant within 6 months as the end point. The models were compared using the Harrell's C index. Recursive partitioning determined the optimal MELDNa cutoff to maximize the risk:benefit ratio of TIPS.

RESULTS

The predictive ability of MELDNa was superior to MELD, particularly in patients with low MELD scores. The C indices (95% confidence interval [CI]) for MELDNa and MELD were 0.65 (95% CI, 0.55-0.71) and 0.58 (95% CI, 0.51-0.67) using a cut-off score of 18, and 0.72 (95% CI, 0.60-0.85) and 0.62 (95% CI, 0.49-0.74) using a cut-off score of 15. Using a MELDNa >15, 22% of patients were reclassified to a higher risk with an event rate of 44% compared with 10% when the score was

CONCLUSIONS

MELDNa performed better than MELD in predicting death or transplant after non-emergent TIPS, especially in patients with low MELD scores. A MELD score