Effect of aliskiren, an oral direct renin inhibitor, on the pharmacokinetics and pharmacodynamics of a single dose of acenocoumarol in healthy volunteers.

OBJECTIVE: Aliskiren is a direct renin inhibitor approved for the treatment of hypertension. This study investigated the effects of aliskiren on the pharmacokinetics and pharmacodynamics of a single dose of acenocoumarol in healthy volunteers. METHODS: This two-sequence, two-period, randomized, double-blind crossover study recruited 18 healthy subjects (ages 18-45) to receive either aliskiren 300 mg or placebo once daily on days 1-10 of each treatment period and a single dose of acenocoumarol 10 mg on day 8. Treatment periods were separated by a 10-day washout. Blood samples were taken frequently for determination of steady-state plasma concentrations of aliskiren (LC-MS/MS) and of R(+)- and S(-)-acenocoumarol (HPLC-UV), prothrombin time (PT) and international normalized ratio (INR). RESULTS: Co-administration with aliskiren had no effect on exposure to R(+)-acenocoumarol. Geometric mean ratios (GMR; aliskiren:placebo co-administration) for R(+)-acenocoumarol AUC(0-t) and C(max) were 1.08 and 1.04, respectively, with 90% CI within the range 0.80-1.25. Co-administration of aliskiren resulted in a 19% increase in S(-)-acenocoumarol AUC(0-t) (GMR 1.19; 90% CI 0.92, 1.54) and a 9% increase in C(max) (GMR 1.09; 90% CI 0.88, 1.34). The anticoagulant effect of acenocoumarol was not affected by co-administration of aliskiren. Geometric mean ratios were 1.01 for all pharmacodynamic parameters (AUC(PT), PT(max), AUC(INR) and INR(max)), with 90% CI within the range 0.97-1.05. CONCLUSION: Aliskiren has no clinically relevant effect on the pharmacokinetics or pharmacodynamic effects of a single dose of acenocoumarol in healthy volunteers, hence no dosage adjustment of acenocoumarol is likely to be required during co-administration with aliskiren.

Lack of pharmacokinetic interactions of aliskiren, a novel direct renin inhibitor for the treatment of hypertension, with the antihypertensives amlodipine, valsartan, hydrochlorothiazide (HCTZ) and ramipril in healthy volunteers.

Aliskiren is a novel, orally active direct renin inhibitor that lowers blood pressure alone and in combination with existing antihypertensive agents. As aliskiren does not affect cytochrome P450 enzyme activities, is minimally metabolised, and is not extensively protein bound, the potential for drug interactions is predicted to be low. Four open-label studies investigated the pharmacokinetic interactions between aliskiren 300 mg and the antihypertensive drugs amlodipine 10 mg (n = 18), valsartan 320 mg (n = 18), hydrochlorothiazide 25 mg (HCTZ, n = 22) and ramipril 10 mg (n = 17) in healthy subjects. In each study, subjects received multiple once-daily doses of aliskiren and the test antihypertensive drug alone or in combination in two dosing periods separated by a drug-free washout period. Plasma concentrations of drugs were determined by liquid chromatography and mass spectrometry methods. At steady state, relatively small changes in exposure to aliskiren were observed when aliskiren was co-administered with amlodipine (AUC(tau) increased by 29%, p = 0.032), ramipril (C(max,ss) increased by 31%, p = 0.043), valsartan (AUC(tau) decreased by 26%, p = 0.002) and HCTZ (C(max,ss) decreased by 22%, p = 0.039). Co-administration with aliskiren resulted in small changes in exposure to ramipril (AUC(tau) increased by 22%, p = 0.002), valsartan (AUC(tau) decreased by 14%, p = 0.062) and HCTZ (AUC(tau) decreased by 10% and C(max,ss) by 26%, both p < 0.001). All other changes in pharmacokinetic parameters were also small, and not statistically significant. None of the observed pharmacokinetic changes was considered clinically relevant. Aliskiren inhibited plasma renin activity (PRA) and also prevented the reactive rise in PRA induced by valsartan. The most commonly reported adverse events were headache, dizziness and gastrointestinal symptoms (all mild in severity), which were similar in frequency during antihypertensive drug treatment alone and in combination with aliskiren except for an increase in dizziness during treatment with the combination of aliskiren and HCTZ. In conclusion, aliskiren shows no clinically relevant pharmacokinetic interactions and is generally well tolerated when administered in combination with amlodipine, valsartan, HCTZ or ramipril.

Pharmacokinetic interaction between verapamil and everolimus in healthy subjects.

AIMS: We sought to define the influence of verapamil, an inhibitor of CYP3A and P-glycoprotein, on the pharmacokinetics of everolimus, a substrate of this enzyme and transporter. METHODS: This was a two-period, single-sequence, crossover study in 16 healthy subjects. In period 1 subjects received a single 2 mg oral dose of everolimus. In period 2 they received verapamil 80 mg three times daily for a total of 6 days and a single 2 mg dose of everolimus co-administered on the second day of verapamil therapy. RESULTS: During verapamil co-administration, everolimus C(max) increased 2.3-fold (90% CI, 1.9, 2.7) from 21 +/- 8 to 47 +/- 18 ng ml(-1) and AUC increased 3.5-fold (90% CI, 3.1, 3.9) from 115 +/- 45 to 392 +/- 142 ng ml(-1) h. Everolimus half-life was only prolonged to a minor extent (32 +/- 6 vs. 37 +/- 6 h). Verapamil predose concentrations doubled from 32 +/- 16 to 74 +/- 42 ng ml(-1) after single dose administration of everolimus. CONCLUSIONS: Multiple dosing with verapamil increased blood concentrations of everolimus after a single dose by an average 3.5-fold. During verapamil treatment, dose reduction for everolimus should be made guided by blood monitoring and for verapamil by blood pressure monitoring.

Blood concentrations of everolimus are markedly increased by ketoconazole.

The authors sought to quantify the influence of the CYP3A and P-glycoprotein inhibitor ketoconazole on the pharmacokinetics of everolimus in healthy subjects. This was a 2-period, single-sequence, crossover study in 12 healthy subjects. In period 1, subjects received the reference treatment of a single 2-mg dose of everolimus. In period 2, they received the test treatment of ketoconazole 200 mg twice daily for a total of 8 days and a single dose of everolimus coadministered on the fourth day of ketoconazole therapy. The test/reference ratio and 90% confidence interval were derived for everolimus maximum concentration and area under the curve. During ketoconazole coadministration, everolimus maximum concentration increased 3.9-fold (90% confidence interval, 3.4-4.6) from 15 +/- 4 ng/mL to 59 +/- 13 ng/mL. Everolimus area under the curve increased 15.0-fold (90% confidence interval, 13.6-16.6) from 90 +/- 23 ng*h/mL to 1324 +/- 232 ng*h/mL. Everolimus half-life was prolonged by 1.9-fold from 30 +/- 4 hours to 56 +/- 5 hours. Everolimus did not appear to alter ketoconazole predose concentrations. Given the magnitude of this drug interaction, use of ketoconazole should be avoided if possible in everolimus-treated patients.

Effect of multiple-dose erythromycin on everolimus pharmacokinetics.

OBJECTIVE: We sought to quantify the influence of the CYP3A inhibitor erythromycin on the pharmacokinetics of everolimus, a CYP3A substrate. METHODS: This was a two-period, single-sequence, crossover study in 16 healthy subjects. In period 1, subjects received the reference treatment of a single 2-mg dose of everolimus. In period 2, they received the test treatment of erythromycin 500 mg three times daily for a total of 9 days and a single 2-mg dose of everolimus coadministered on the fifth day of erythromycin therapy. The test/reference ratio and 90% confidence interval (CI) were derived for everolimus C (max) and AUC. RESULTS: During erythromycin coadministration, everolimus C (max) increased 2.0-fold (90% CI, 1.8-2.3) from 20+/-5 ng/ml to 40+/-10 ng/ml. Everolimus AUC increased 4.4-fold (90% CI, 3.5-5.4) from 116+/-37 ng h/ml to 524+/-225 ng h/ml. Everolimus half-life was prolonged by 39% from 32+/-6 h to 44+/-6 h. Erythromycin predose concentrations were not changed after single-dose administration of everolimus. CONCLUSION: Multiple-dose erythromycin increased single-dose everolimus blood levels by an average 4.4-fold (range, 2.0-12.6). During erythromycin treatment, a compensatory everolimus dose reduction should be made guided by everolimus therapeutic drug monitoring.

JAHK: a low frequency antigen associated with the rG complex of the Rh blood group system.

We have investigated a 'new' low frequency antigen JAHK, which is a marker for the rare Rh gene complex rG. The rG haplotype does not produce any D, c or E antigens, but does produce a strong G antigen. The rG haplotype [d(C)(e)G] is associated with weak C and weak e antigens. Three unrelated rG/dce individuals and one rG/rG propositus were JAHK+. In addition, three propositi whose red cells had a typical expression of C and/or e antigen, which could not be shown to be rG because of a normal D antigen produced by the haplotype in trans, were also JAHK+. Families of three of the propositi demonstrate the inheritance of JAHK as a Mendelian dominant character. It is likely that the JAHK antigen results from conformational changes in an RhCcEe protein that has the amino acid characteristic of c antigen at position 16 and the amino acid residues characteristic of C antigen at positions 60, 68, and 103. JAHK has been assigned the number RH53.

An antiserum identifying a red cell determinant expressed by Rh:33 and by some "new" depressed Rh phenotypes.

An antibody detecting a determinant on Rh:33 cells and cells with depressed C and/or e antigens was separated by the absorption and elution technique from a serum with antibodies to several low-frequency antigens. The determinant, tentatively named FPTT, has a frequency of about 0.0094 percent in the South of France.

[The importance of HLA typing in cases of disputed paternity]. / Intérêt des groupages HLA dans les problèmes de paternite discutée.

In dispute paternity, the biologists must reply to two questions: 1. Is the paternity excluded or possible? 2. If it is possible, what is its probability? Valid answers can be given, using several genetic markers, among which HLA genes are specially interesting. Looking at HLA-A, B, C, DR typing of child, mother and presumed father, we propose a method which allows a direct calculation of paternity probability. Crossing over between HLA genes in presumed father and in mother are also considered in this method. In our experience, adding the date provided by the HLA genes and other genetic markers, we obtained, either formal exclusions, or possible paternities with a probability almost always higher than 90%.

[Phenotyping Kell and Duffy antigens by a technic of coagglutination on the Groupamatic G 360]. / Phénotypage Kell et Duffy par une technique de coagglutination sur Groupmatic G 360.

By adapting the technique of coagglutination to the Groupamatic, we have developed an efficient rapid method of phenotyping donors for the Kell and Fya antigens. 340 specimens can be tested per hour; 800 tests can be performed with only 15 ml of antisera. Over 10,000 donor specimens were tested for Kell and 2,470 were simultaneously phenotyped for Fya. No false negatives were observed. The rate, of false positive results, due to autoagglutinins coating the donors' red cells, was the same as that seen with the continuous flow method. We conclude that this technique is suitable for routine use in screening donors for Kell and Fya antigens.

[Detection and identification of irregular anti-erythrocyte antibodies with the Groupamatic G 360. Adaptation to the routine]. / Dépistage et identification des anticorps irréguliers antiérythrocytaires sur Groupamatic G 360. Adaptation à la routine.

The screening of irregular red-cell antibodies on 20.200 recipient samples was carried out simultaneously on continuous flux AUTO-ANALYZER (LIP-bromeline) and GROUPAMATIC (TPC-bromeline). From results it appears: --an equivalent sensibility of both technologies to detect Rh, Kell, Duffy and Kidd antibodies; --a higher sensibility of Groupamatic to detect particularly Lewis and P1 antibodies; --a clear superiority of TPC compared to bromeline technique which is commonly used with Groupamatic. Small modifications of the standard TPC system allow to associate, in routine work, detection of irregular red-cell antibodies with other analyses, such as ABO Rh grouping and phenotyping. From this last point of view, a restricted test of coagglutination phenotyping has revealed to be very promising.