An open-label study in healthy men to evaluate the risk of seminal fluid transmission of denosumab to pregnant partners.

AIMS: Denosumab is a fully human monoclonal immunoglobulin G2 antibody that inhibits bone resorption and increases bone mass and strength. The present clinical study assessed serum and seminal fluid pharmacokinetics following a single denosumab dose in healthy men, and evaluated whether denosumab in seminal fluid poses any risk to a fetus in the event of unprotected sexual intercourse with a pregnant partner. METHODS: An open-label, single-dose study in 12 healthy men was conducted over a 106-day period. Subjects received a single subcutaneous dose of 60-mg denosumab on day 1. Serum and seminal fluid samples were collected at specified time points to assess denosumab pharmacokinetics. Adverse events were recorded. RESULTS: Denosumab was measurable at low concentrations in seminal fluid (~2% of serum concentrations). The mean [standard deviation (SD)] maximum observed drug concentration (Cmax ) was 6170 (2070) ng ml(-1) (serum) and 100 (81.9) ng ml(-1) (seminal fluid). The median time to Cmax (tmax ) was 8 days (serum) and 21 days (seminal fluid). The mean (SD) area under the plasma concentration-time curve (AUC) from time zero to the time of the last quantifiable concentration (AUClast ) was 333 000 (122 000) day•ng ml(-1) (serum) and 5220 (4880) day•ng ml(-1) (seminal fluid). The mean (SD) Cmax and AUC ratios between seminal fluid and serum were 0.0217 (0.0154) and 0.0170 (0.0148), respectively. Using conservative assumptions for ejaculate volume (6 ml), vaginal absorption (100%) and placental transfer (100%), the measured mean denosumab seminal fluid Cmax would result in fetal exposure that was more than 110 times below the preclinically derived 'no effect level' for denosumab. CONCLUSIONS: These results indicate a negligible risk to a fetus exposed to denosumab via seminal fluid transfer to a pregnant partner.

Comparison of pharmacokinetics and safety of pegfilgrastim administered by two delivery methods: on-body injector and manual injection with a prefilled syringe.

PURPOSE: For patients with clinically significant risk of febrile neutropenia, pegfilgrastim administration should occur the day after myelosuppressive chemotherapy; however, a variety of factors may preclude patients from returning to the clinic the next day for pegfilgrastim administration, necessitating other strategies. This study compared the pharmacokinetics and safety of pegfilgrastim administered via an on-body injector applied to the subject's skin versus manual injection using a prefilled syringe. METHODS: Healthy subjects aged 18-50 years were randomized 1:1 to receive a single 6-mg subcutaneous pegfilgrastim dose from an on-body injector or a prefilled syringe. Blood for pharmacokinetic measurements was collected at baseline and prespecified time points after pegfilgrastim administration; safety was assessed throughout the 6-week study. Primary endpoints were maximum concentration (C max) and area under the concentration curve from time 0 to infinity (AUC0-inf). Secondary endpoints included safety, tolerability, and immunogenicity. RESULTS: Pegfilgrastim mean AUC0-inf values for the on-body injector (n = 125) and manual injection (n = 128) were 10,900 and 11,100 h ng/mL, respectively; mean C max values were 248 and 262 ng/mL, respectively. The least squares geometric mean ratios were 0.97 for C max and 1.00 for AUC0-inf; the corresponding 90 % CIs were within the prespecified range (0.80-1.25), indicating comparable pegfilgrastim pharmacokinetics between delivery methods. Treatment-emergent adverse events (AEs) were similar between groups (injector, 86 %; manual, 85 %). Injector- or syringe-related AEs were more prevalent with the injector (13 %; manual, 4 %); none were serious. No pegfilgrastim-neutralizing antibodies were detected. CONCLUSIONS: Pegfilgrastim pharmacokinetics and safety were comparable between the on-body injector and manual injection groups.

Pharmacological inhibition of myostatin and changes in lean body mass and lower extremity muscle size in patients receiving androgen deprivation therapy for prostate cancer.

CONTEXT: Myostatin is a negative regulator of muscle growth. Androgen deprivation (ADT) is associated with muscle loss and increased body fat, and currently available therapies have limited efficacy to treat this complication. The antimyostatin peptibody (AMG 745/Mu-S) markedly attenuated muscle loss and decreased fat accumulation in orchiectomized mice. OBJECTIVE: The objective of the study was to evaluate the safety, pharmacokinetics, and muscle efficacy of AMG 745 in men undergoing ADT for nonmetastatic prostate cancer. METHODS: This was a randomized, blinded, placebo-controlled, multiple-dose, phase 1 study of AMG 745 given for 28 days. The end point of percentage change from baseline in lean body mass (LBM) as assessed by dual x-ray absorptiometry was prespecified. RESULTS: Rates of adverse events (AMG 745 vs placebo) were the following: diarrhea (13% vs 9%), fatigue (13% vs 4%), contusion (10% vs 0%), and injection site bruising (6% vs 4%). Exposure increased linearly from 0.3 mg/kg to 3 mg/kg. AMG 745 significantly increased LBM in the 3 mg/kg vs the placebo groups on day 29 by 2.2% (±0.8% SE, P = 0.008); in exploratory fat mass analysis, a decrease of -2.5% (±1.0% SE, P = 0.021) was observed. Pharmacodynamic changes in muscle and fat were maintained at follow-up, 1 month after day 29. CONCLUSION: Four weekly s.c. doses of AMG 745 were well tolerated and were associated with increased LBM and decreased fat in the men receiving ADT for nonmetastatic prostate cancer. RESULTS support further investigation of AMG 745 in clinical settings with muscle loss and atrophy.

Multiple doses of sclerostin antibody romosozumab in healthy men and postmenopausal women with low bone mass: a randomized, double-blind, placebo-controlled study.

Romosozumab (formerly AMG 785/CDP7851) is a monoclonal antibody that blocks sclerostin from inhibiting osteoblast maturation and function. This double-blind, placebo-controlled, randomized, ascending multiple-dose study enrolled 32 postmenopausal women and 16 healthy men with low bone mass. Women received six doses of 1 or 2 mg/kg once every 2 weeks (Q2W) or three doses of 2 or 3 mg/kg once every 4 weeks (Q4W) or placebo; and men received 1 mg/kg Q2W or 3 mg/kg Q4W or placebo. Mean serum romosozumab exposures increased approximately dose-proportionally. Romosozumab increased serum type 1 aminoterminal propeptide (PINP) by 66-147%, decreased serum C-telopeptide (sCTX) by 15-50%, and increased lumbar spine bone mineral density by 4-7%. Two subjects developed neutralizing antibodies without discernable effects on pharmacokinetics, pharmacodynamics, or safety. Adverse event rates were balanced between groups without any significant safety findings. These data support continued investigation of sclerostin inhibition in disorders that could benefit from increased bone formation.

A single-dose study of denosumab in patients with various degrees of renal impairment.

This 16-week study evaluated pharmacokinetics and pharmacodynamics of denosumab in 55 subjects with renal function ranging from normal to dialysis-dependent kidney failure. Participants received a single 60-mg subcutaneous dose of denosumab. Kidney function groups were based on calculations using the Cockcroft-Gault equation and U.S. Food and Drug Administration (FDA) guidance in place when the study was designed. Renal function did not have a significant effect on denosumab pharmacokinetics or pharmacodynamics. These findings suggest denosumab dose adjustment based on glomerular filtration rate is not required. Rapid decreases in serum C-telopeptide in all groups were sustained throughout the study. The most common adverse events were hypocalcemia (15%), pain in extremity (15%), and nausea (11%). Most adverse events were mild to moderate in severity. Calcium and vitamin D supplementation was not initially required by the study protocol, but was added during the trial. No subject who received adequate calcium and vitamin D supplementation became hypocalcemic. Seven subjects had nadir serum calcium concentrations between 7.5 and <8.0 mg/dL (1.9 and <2.0 mmol/L), and 5 subjects (4 with advanced renal disease) had nadir serum calcium <7.5 mg/dL (<1.9 mmol/L). Two subjects (1 symptomatic, 1 asymptomatic) were hospitalized for intravenous calcium gluconate treatment. At the recommended dose, denosumab is a useful therapeutic option for patients with impaired renal function. Supplementation of calcium and vitamin D is strongly recommended when patients initiate denosumab therapy, particularly in patients with reduced renal function.

Clinical pharmacokinetic and pharmacodynamic profile of cinacalcet hydrochloride.

Cinacalcet hydrochloride (cinacalcet) is a calcimimetic approved for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease (CKD) receiving dialysis and for the treatment of hypercalcaemia in patients with parathyroid carcinoma. Following oral administration, peak plasma concentrations of cinacalcet occur within 2-6 hours. The absolute bioavailability is 20-25%, and administration of cinacalcet with low- or high-fat meals increases exposure (area under the plasma concentration-time curve from time zero to infinity [AUC(infinity)]) 1.5- to 1.8-fold. Cinacalcet has no significant interaction with calcium carbonate or sevelamer hydrochloride, phosphate binders commonly used in the treatment of patients with CKD receiving dialysis. The terminal elimination half-life is 30-40 hours, and steady-state concentrations are achieved within 7 days. The pharmacokinetics of cinacalcet are dose proportional over the dose range of 30-180 mg. The pharmacokinetic profile of cinacalcet is not notably affected by varying degrees of renal impairment. The pharmacokinetics of cinacalcet are comparable between healthy subjects, patients with primary hyperparathyroidism and patients with secondary hyperparathyroidism with reduced renal function (including those patients with secondary hyperparathyroidism receiving dialysis). Additionally, the pharmacokinetics of cinacalcet are similar in patients with secondary hyperparathyroidism receiving haemodialysis and patients with secondary hyperparathyroidism receiving peritoneal dialysis. Mild hepatic impairment does not affect the pharmacokinetics of cinacalcet, whereas moderate or severe hepatic impairment increases the exposure (AUC(infinity)) by approximately 2- and 4-fold, respectively. Age, sex, bodyweight and race do not notably affect the pharmacokinetics of cinacalcet. Cinacalcet is extensively metabolized by multiple hepatic cytochrome P450 (CYP) enzymes (primarily 3A4, 2D6 and 1A2) with <1% of the parent drug excreted in the urine. Dose adjustments of cinacalcet may be necessary, and parathyroid hormone (PTH) and serum calcium concentrations should be closely monitored if a patient initiates or discontinues therapy with a strong CYP3A4 inhibitor (e.g. ketoconazole, erythromycin, itraconazole). Cinacalcet is a strong inhibitor of CYP2D6; therefore, dose adjustment of concomitant medications that are predominantly metabolized by CYP2D6 and have a narrow therapeutic index (e.g. flecainide, vinblastine, thioridazine and most tricyclic antidepressants) may be required. Cinacalcet does not appreciably inhibit or induce the activities of CYP3A4, 1A2, 2C9 or 2C19. An inverse relationship exists between plasma PTH and cinacalcet concentrations. PTH concentrations are greatest before dose administration when the cinacalcet concentration is lowest (24 hours after the previous day's dose). Nadir PTH levels occur approximately 2-3 hours after dosing.

Cinacalcet does not affect the activity of cytochrome P450 3A enzymes, a metabolic pathway for common immunosuppressive agents : a randomized, open-label, crossover, single-centre study in healthy volunteers.

BACKGROUND AND OBJECTIVE: Cinacalcet HCl (cinacalcet) is approved for the treatment of secondary hyperparathyroidism in subjects receiving dialysis and for the reduction of hypercalcaemia in patients with parathyroid carcinoma. The drug may also be co-administered with medications used in the renal transplantation setting, such as immunosuppressants. Cinacalcet, as well as some immunosuppressants such as ciclosporin, tacrolimus and sirolimus, is partially metabolized by the cytochrome P450 3A enzymes (CYP3A). This study aimed to evaluate the potential inhibitory effects of cinacalcet on CYP3A activity using midazolam as a probe substrate in healthy volunteers. METHODS: In this randomized, open-label, crossover, two-treatment, two-period, single-centre study, 12 healthy volunteers received either oral cinacalcet 90 mg once daily for 5 days plus a single oral dose of midazolam 2 mg on day 5, or a single oral dose of midazolam 2 mg on day 1. Following a 10-day washout period, subjects received the alternate treatment. Blood samples were collected predose and at selected time points up to 24 hours after dosing with midazolam for measurement of midazolam pharmacokinetic parameters. RESULTS: Eleven subjects completed the study. Mean (standard deviation) midazolam maximum plasma concentrations (C(max)) and area under the plasma concentration-time curve from time zero to infinity (AUC(infinity)) were 9.31 (3.09) ng/mL and 24.1 (7.7) ng . h/mL, respectively, when administered in combination with cinacalcet, compared with 9.76 (2.81) ng/mL and 22.8 (6.1) ng . h/mL when administered alone. The mean geometric ratios (90% confidence interval) were 0.95 (0.84, 1.06) and 1.05 (0.95, 1.16) for C(max) and AUC(infinity), respectively. All adverse events were mild to moderate in severity, and consistent with the safety profile of cinacalcet. CONCLUSION: Once-daily administration of cinacalcet did not alter the pharmacokinetics of midazolam relative to administration of midazolam alone. These data suggest that cinacalcet administration does not affect CYP3A activity, and thus would not have an effect on any drug eliminated via CYP3A, including some commonly used immunosuppressant therapies.

The pharmacokinetics of cinacalcet are unaffected following consumption of high- and low-fat meals.

Cinacalcet HCl reduces iPTH, serum calcium, serum phosphorus, and the calcium-phosphorus product in patients with chronic kidney disease and secondary hyperparathyroidism who are receiving dialysis, and reduces elevated serum calcium associated with primary hyperparathyroidism and parathyroid carcinoma. Cinacalcet is administered orally, and thus concomitant administration with food may affect its bioavailability. The objective of this study was to examine the effect of fat and caloric intake on cinacalcet exposure. This phase 1, randomized, open-label, single-dose, 3-period, 3-treatment, 6-sequence crossover study enrolled 30 healthy subjects (19 men, 11 women) to receive a single oral dose of cinacalcet HCl (Sensipar/Mimpara; Amgen Inc. Thousand Oaks, CA) (90 mg) on 3 separate occasions: following a high-fat, high-caloric meal, a low-fat, low-caloric meal, and a 10-hour fast. Blood samples were obtained predose and up to 72 hours postdose for pharmacokinetic (AUCinfinity, Cmax) and safety evaluations. Twenty-nine subjects completed all the 3 treatment conditions. The mean (90% confidence intervals) AUCinfinity following high- and low-fat meals was increased by 68 (48 to 89)% and 50 (33 to 70)%, respectively, relative to fasting. The difference in mean AUCinfinity between high- and low-fat meals was small [12 (9.9-26)%]. The mean tmax of cinacalcet was prolonged in fasting subjects (6 h) in relation to high-fat (4 h) and low-fat (3.5 h) fed subjects. The mean t1/2beta was similar between treatment conditions. Adverse events (AE) were observed at a similar frequency across the treatment conditions [high fat (34%), low fat (23%), and fasting (31%)]; the type of AE did not differ among the treatment conditions. The most common treatment-related AEs were headache 6/30 (20%), nausea 5/30 (17%), and dyspepsia 4/30 (13%) subjects. Administration of cinacalcet with either high- or low-fat meals results in significant increases in exposure, relative to administration under fasting conditions. However, the small differences observed in exposure following the ingestion of the different types of meals suggest that although food has a significant effect, the type of food does not. The observed effect supports the labeling statement that cinacalcet be taken with food, or shortly after a meal.

Pharmacology of darbepoetin alfa.

The distinct molecular structure of darbepoetin alfa, in both its amino acid sequence and its carbohydrate content, results in a biologic profile with lower binding affinity, longer circulating half-life, and higher in vivo potency compared with the epoetins. The mechanisms responsible for these differences in biological effects have not been fully explained. Pharmacokinetic investigations of darbepoetin alfa using prolonged blood sampling times established that the mean terminal half-life after subcutaneous (SC) administration is 70 to 105 hours. Pharmacodynamic studies were conducted to assess the suitability of darbepoetin alfa for use in weekly or less frequent (once every other week or once a month) dosing regimens to maintain haemoglobin levels in patients with anaemia of renal disease. Regardless of dialysis status, route of administration, or prior treatment with an erythropoiesis-stimulating agent, darbepoetin alfa administered at extended intervals was able to raise or maintain hemoglobin levels to target. More rigorous studies will be needed to confirm these findings.

Cinacalcet does not affect the pharmacokinetics or pharmacodynamics of warfarin.

BACKGROUND AND OBJECTIVE: Cinacalcet HCl (cinacalcet), approved for secondary hyperparathyroidism and parathyroid carcinoma-associated hypercalcaemia, may be coadministered with warfarin. The purpose of this study was to determine the pharmacokinetics/pharmacodynamics and tolerability of warfarin during cinacalcet coadministration. SUBJECTS AND METHODS: In this phase 1, randomised, double-blind, placebo-controlled, two-treatment, two-period crossover study, 21 healthy subjects received oral cinacalcet (30 mg) or placebo twice a day for 7 days and once on day 8, with a single warfarin dose (25mg) on day 5. After a 3-week washout, subjects received the alternative treatment. Samples for warfarin pharmacokinetics/pharmacodynamics were obtained until 144 hours post-dose. RESULTS: Single-dose administration of warfarin to subjects receiving cinacalcet did not demonstrate altered pharmacodynamics of either the R- or S-enantiomer. Geometric means ratio (90% CIs) for R- and S-warfarin were 1.01 (0.95, 1.07) and 1.00 (0.94, 1.04), respectively, for the area under the plasma concentration-time curve from time 0 to infinity (AUC(infinity)) and 0.90 (0.84, 0.96) and 0.88 (0.83, 0.94), respectively, for observed maximum plasma concentrations (C(max)). Additionally, the pharmacokinetic profiles of R- or S-warfarin were similar for all subjects. The ratio for the AUC from time 0 to the last measurable concentration (AUC(t)) for prothrombin time and factor VII were 1.03 (1.01, 1.04) and 0.97 (0.93, 1.01), respectively. The maximum rise (R(max)) and maximum change (Delta(max)) were 1.04 (1.02, 1.05) and 1.00 (0.96, 1.03), respectively. All treatment-emergent and treatment-related adverse events were mild to moderate in severity. There were no obvious differences in adverse events according to treatment. CONCLUSION: Warfarin pharmacokinetics/pharmacodynamics were not affected in subjects treated with warfarin 25mg who received cinacalcet 30 mg twice daily, thus suggesting that dose adjustment is not required.