Comparative Performance of Two Drug Interaction Screening Programmes Analysing a Cross-Sectional Prescription Dataset of 84,625 Psychiatric Inpatients.

Comparative Performance of Two Drug Interaction Screening Programmes Analysing a Cross-Sectional Prescription Dataset of 84,625 Psychiatric Inpatients.

Drug Saf. 2013 Mar 14;
Zorina OI, Haueis P, Greil W, Grohmann R, Kullak-Ublick GA, Russmann S

BACKGROUND: Clinical decision support software (CDSS) solutions can automatically identify drug interactions and thereby aim to improve drug safety. However, data on the comparative performance of different CDSS to detect and appropriately classify interactions in real-life prescription datasets is limited. OBJECTIVE: The aim of this study was to compare the results from two different CDSS analysing the pharmacotherapy of a large population of psychiatric inpatients for drug interactions. METHODS: We performed mass analyses of cross-sectional patient-level prescriptions from 84,625 psychiatric inpatients using two CDSS – MediQ and ID PHARMA CHECK(®). Interactions with the highest risk ratings and the most frequent ratings were reclassified according to the Zurich Interaction System (ZHIAS), a multidimensional classification that incorporates the OpeRational ClassificAtion of Drug Interactions (ORCA) and served as a reference standard. RESULTS: MediQ reported 6,133 unique interacting combinations responsible for 270,617 alerts affecting 63,454 patients. ID PHARMA CHECK(®) issued 5,400 interactions and 157,489 alerts in 48,302 patients. Only 2,154 unique interactions were identified by both programmes, but overlap increased with higher risk rating. MediQ reported high-risk interactions in 2.5 % of all patients, compared with 5 % according to ID PHARMA CHECK(®). The positive predictive value for unique major alerts to be (provisionally) contraindicated according to ORCA was higher for MediQ (0.63) than for either of the two ID PHARMA CHECK(®) components (0.42 for hospINDEX and 0.30 for ID MACS). MediQ reported more interactions, and ID PHARMA CHECK(®) tended to classify interactions into a higher risk class, but overall both programmes identified a similar number of (provisionally) contraindicated interactions according to ORCA criteria. Both programmes identified arrhythmia as the most frequent specific risk associated with interactions in psychiatric patients. CONCLUSIONS: CDSS can be used for mass-analysis of prescription data and thereby support quality management. However, in clinical practice CDSS impose an overwhelming alert burden on the prescriber, and prediction of clinical relevance remains a major challenge. Only a small subset of yet to be determined alerts appears suitable for automated display in clinical routine. HubMed – drug

Simultaneous Pharmacogenetics-Based Population Pharmacokinetic Analysis of Darunavir and Ritonavir in HIV-Infected Patients.

Clin Pharmacokinet. 2013 Mar 15;
Moltó J, Xinarianos G, Miranda C, Pushpakom S, Cedeño S, Clotet B, Owen A, Valle M

BACKGROUND: Darunavir is a potent protease inhibitor of HIV. To enhance its pharmacokinetic profile, darunavir must be co-administered with ritonavir. There is wide inter-patient variability in darunavir pharmacokinetics among HIV-infected individuals, however. Darunavir is a known substrate for influx transporters, such as the 1A2 and the 1B1 members of the solute carrier organic anion transporter family (SLCO1A2, SLCO1B1), as well as for efflux transporters such as the multi-drug resistance protein 1 (MRP1). OBJECTIVE: The aim of this study was to develop a semi-mechanistic population pharmacokinetic model for darunavir and ritonavir administered in HIV-infected adults. The desired model would incorporate patient characteristics and pharmacogenetic data contributing to variability in drug concentrations and also take into account the interaction between the two compounds. METHODS: A population pharmacokinetic analysis was performed with 705 plasma samples from 75 Caucasian individuals receiving darunavir/ritonavir (600/100 mg twice daily) for at least 4 weeks. At least one full pharmacokinetic profile was obtained for each participant, and darunavir and ritonavir concentrations in plasma were determined by high performance liquid chromatography. Genotyping for 148 polymorphisms in genes coding for transporters or metabolizing enzymes was conducted by two methods: MALDI-TOF mass spectrometry and real-time polymerase chain reaction-based allelic discrimination. A population pharmacokinetic model was developed for darunavir and for ritonavir. The effect of single nucleotide polymorphisms on the post hoc individual pharmacokinetic parameters was first explored using graphic methods and regression analysis. Those covariates related to changes in darunavir or ritonavir pharmacokinetic parameters were then further evaluated using non-linear mixed effects modeling (NONMEM version VII). RESULTS: Darunavir and ritonavir pharmacokinetics were best described by a two- and one-compartment model, respectively, both with first-order absorption and elimination. The darunavir peripheral volume of distribution decreased as ?1-acid glycoprotein concentrations increased. Darunavir clearance was 12 % lower in patients with SLCO3A1 rs8027174 GT/TT genotypes, while homozygosity for the rs4294800 A allele was associated with 2.5-fold higher central volume of distribution. Body weight influenced ritonavir clearance. Ritonavir inhibited darunavir clearance following a maximum-effect model. CONCLUSION: A population pharmacokinetic model to simultaneously describe the pharmacokinetics of darunavir and ritonavir was developed in HIV-infected patients. The model provides better understanding of the interaction between darunavir and ritonavir and suggests an association between SLCO3A1 polymorphisms and darunavir pharmacokinetics. Bayesian estimates of individual darunavir parameters and ritonavir may be useful to predict darunavir exposure. HubMed – drug

A Novel Double-Tracer Technique to Characterize Absorption, Distribution, Metabolism and Excretion (ADME) of [(14)C]Tofogliflozin After Oral Administration and Concomitant Intravenous Microdose Administration of [ (13)C]Tofogliflozin in Humans.

Clin Pharmacokinet. 2013 Mar 14;
Schwab D, Portron A, Backholer Z, Lausecker B, Kawashima K

BACKGROUND: Human mass balance studies and the assessment of absolute oral bioavailability (F) are usually assessed in separate studies. Intravenous microdose administration of an isotope tracer concomitant to an unlabeled oral dose is an emerging technique to assess F. We report a novel double-tracer approach implemented for tofogliflozin combining oral administration of a radiolabel tracer with concomitant intravenous administration of a stable isotope tracer. Tofogliflozin is a potent and selective sodium/glucose cotransporter 2 inhibitor for the treatment of type 2 diabetes mellitus currently in clinical development. OBJECTIVES: The objectives of the present study were to assess the systemic exposure of major circulating metabolites, excretion balance, F and contribution of renal clearance (CLR) to total clearance (CL) of tofogliflozin in healthy subjects within one study applying a novel double-tracer technique. METHODS: Six healthy male subjects received 20 mg [(12)C/(14)C]tofogliflozin (3.73 MBq) orally and a concomitant microdose of 0.1 mg [(13)C]tofogliflozin intravenously. Pharmacokinetics of tofogliflozin were determined for the oral and intravenous route; the pharmacokinetics of the metabolites M1 and M5 were determined for the oral route. Quantification of [(12)C]tofogliflozin in plasma and urine and [(13)C]tofogliflozin in plasma was performed by selective LC-MS/MS methods. For the pre-selected metabolites of tofogliflozin, M1 and M5, a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied to plasma and urine samples. Total radioactivity was assessed in plasma, urine and feces. Pharmacokinetic analysis was conducted by non-compartmental methods. RESULTS: The pharmacokinetics of tofogliflozin in healthy subjects were characterized by an F of 97.5 ± 12.3 %, CL of 10.0 ± 1.3 l/h and volume of distribution at steady-state (V ss) of 50.6 ± 6.7 l. The main route of elimination of total drug-related material was by excretion into urine (77.0 ± 4.1 % of the dose). The observed CLR of 25.7 ± 5.0 ml/min was higher than the product of the estimated glomerular filtration rate (eGFR) and fraction unbound in plasma (f u) (eGFR × f u 15 ml/min), indicating the presence of net active tubular secretion in the renal elimination of tofogliflozin. However, CLR contributed only 15.5 % to the CL of tofogliflozin, suggesting that reductions in CLR by renal impairment won’t significantly affect systemic exposure to tofogliflozin. Tofogliflozin and its metabolite M1 were the only major circulating entities accounting for 46 ± 8.6 and 50 ± 8.2 %, respectively, of total circulating drug-related material, while the metabolite M5 was a minor circulating metabolite accounting for 3.0 ± 0.3 % of total circulating drug-related material. Both the M1 and M5 metabolites were excreted into urine and the major metabolite M1 did not exhibit active tubular secretion. CONCLUSIONS: These results demonstrate the utility of the double-tracer approach to provide essential pharmacokinetic data and excretion data for drug-related material in one study at the same dosing occasion. The data obtained allowed the characterization of absorption, distribution, metabolism and excretion of tofogliflozin. Tofogliflozin exhibited highly favorable pharmacokinetic properties as demonstrated by its high F, low CL and a low V ss. The presence of only one major circulating metabolite of tofogliflozin was unambiguously demonstrated. As a drug targeting the kidney, luminal exposure of the kidney is achieved by renal filtration and active tubular secretion. HubMed – drug

Characterizing Systemic Exposure of Inhaled Drugs: Application to the Long-Acting ?2-Agonist PF-00610355.

Clin Pharmacokinet. 2013 Mar 14;
Diderichsen PM, Cox E, Martin SW, Cleton A, Ribbing J

BACKGROUND AND OBJECTIVES: PF-00610355 is an orally inhaled long-acting ?2-adrenoreceptor agonist that is being developed for the once-daily treatment of chronic obstructive pulmonary disease (COPD). The pharmacological effect is exerted in the lungs. However, systemic exposure of PF-00610355 is expected to be responsible for certain drug-related adverse effects. This analysis characterizes PF-00610355 using an integrated analysis of systemic exposure, across trials and patient populations. METHODS: A total of 6,107 samples of PF-00610355 plasma concentration, collected in 264 subjects from eight studies in healthy volunteers, asthma, and COPD patients, were analyzed using non-linear mixed-effects models. Model-based mean (95 % CI) exposure profiles for a range of PF-00610355 doses in COPD patients were simulated. RESULTS: PF-00610355 exposure profiles were described by a three-compartment disposition model with first-order absorption through a transit compartment. Patient status, inhalation device, and demographic factors were found to influence systemic drug exposure. Relative fine particle dose had a minor effect, whereas no effect of baseline lung function on the systemic exposure was found. An implicit method to address pharmacokinetic variability between occasions of drug intake yielded similar results as the established explicit method, yet in a much more efficient way. CONCLUSION: The estimated systemic pre-dose and maximum PF-00610355 plasma concentration was 23 and 38 % in COPD patients compared to healthy volunteers, respectively. The analysis illustrated the value of an integrated pharmacokinetic analysis to address specific challenges in the clinical development of long-/ultra-long-acting ?2-agonists and inhaled compounds in general, both in relation to selecting a safe starting dose in patients, but also in understanding exposure and systemic safety information across different patient populations and different inhalation devices/formulations. HubMed – drug

Disposition Pathway-Dependent Approach for Predicting Organic Anion-Transporting Polypeptide-Mediated Drug-Drug Interactions.

Clin Pharmacokinet. 2013 Mar 15;
Hu ZY

BACKGROUND AND OBJECTIVE: Organic anion-transporting polypeptide (OATP)-mediated drug-drug interactions (DDIs) are among the most important classes of clinically relevant DDIs. Accurate prediction of the OATP-mediated DDIs is not successful due to the sequential disposition pathways of OATP substrates in humans. Intestinal and hepatic uptake transporters, efflux transporters, and cytochrome P450 (CYP) enzymes are often involved in the sequential disposition pathways of typical OATP substrates. The aim of this proof-of-concept study is to develop and validate a novel approach which can be used to predict OATP-mediated DDIs with significantly increased accuracy and decreased false-negatives. METHODS: The feasibility of using a disposition pathway-dependent prediction (DPDP) approach to predict the ratios of the area under the plasma concentration-time curve (AUCR) in the presence and absence of the inhibitor was investigated. A total of 62 clinical DDI studies were included in this feasibility study. The disposition pathways governing the outcome of DDIs were first identified for each substrate using the information within learning sets, and then substrate-specific algorithms were used to predict the DDI risks of the external validation set (51 DDIs). RESULTS: The method predicted AUCR within 50-200 % for 50 studies (98 %), and the false-negative rate was 9.8 %. The DPDP approach showed significant improvement over an existing approach and was used to forecast the magnitude of 198 DDIs that have not been studied. CONCLUSION: This approach can be used to avoid unnecessary clinical DDI studies during new drug development. HubMed – drug