Pharmacokinetic study between a bilayer matrix fentalyl patch and a monolayer matrix fentanyl patch: single dose administration in healthy volunteers.

AIMS: Transdermal fentanyl is a well established treatment for cancer pain. The aim of the present study is to assess the relative bioavailability of fentanyl from two different transdermal systems by evaluating plasma drug concentrations after single administration of Fentalgon® (test), a novel bilayer matrix type patch, and Durogesic SMAT (reference), a monolayer matrix type patch. In the Fentalgon patch the upper 6% fentanyl reservoir layer maintains a stable concentration gradient between the lower 4% donor layer and the skin. The system provides a constant drug delivery over 72 h. METHODS: This was an open label, single centre, randomized, single dose, two period crossover clinical trial, that included 36 healthy male volunteers. The patches were applied to non-irritated and non-irradiated skin on the intraclavicular pectoral area. Blood samples were collected at different time points (from baseline to 120 h post-removal of the devices) and fentanyl concentrations were determined using a validated LC/MS/MS method. Bioequivalence was to be claimed if the 90% confidence interval of AUC(0,t) and C(max) ratios (test: reference) were within the acceptance range of 80-125% and 75-133%, respectively. RESULTS: The 90% confidence intervals of the AUC(0,t) ratio (116.3% [109.6, 123.4%]) and C(max) ratio (114.4% [105.8, 123.8%] were well included in the acceptance range and the C(max) ratio also met the narrower bounds of 80-125%. There was no relevant difference in overall safety profiles of the two preparations investigated, which were adequately tolerated, as expected for opioid-naïve subjects. CONCLUSIONS: The new bilayer matrix type patch, Fentalgon®, is bioequivalent to the monolayer matrix type Durogesic SMAT fentanyl patch with respect to the rate and extent of exposure of fentanyl (Eudra/CT no. 2005-000046-36).

Mechanistic Considerations About an Unexpected Ramipril Drug-Drug Interaction in the Development of a Triple Fixed-Dose Combination Product Containing Ramipril, Amlodipine, and Atorvastatin.

This open-label, repeat-dose, fixed-sequence study in healthy subjects examined pharmacokinetic drug-drug interactions between the components of a novel fixed-dose combination product containing ramipril, amlodipine, and atorvastatin. Sequential 5-day monotreatments (MTs) of ramipril (5 mg/d) and atorvastatin (40 mg/d) were followed by a 9-day amlodipine MT (5 mg/d), separated by 96 hours washout intervals. After amlodipine MT, all 3 single-entity drugs were coadministered for 5 days. Blood samples were taken over the dosing intervals and drug concentrations quantified by high-performance liquid chromatography-mass spectrometry. Pharmacokinetic parameters were assessed and compared between the MTs and combination treatments by analysis of variance. Eighteen healthy subjects were enrolled and completed the study. No significant difference in maximum concentration (Cmax ) and area under the plasma concentration-time curve over the dosing interval (AUC0-τ ) for amlodipine and AUC0-τ of atorvastatin was observed upon combination treatments versus MTs. Cmax of atorvastatin was slightly decreased (Cmax ratio, 89.3%) when given in combination. Increased exposure of ramipril and less pronounced exposure of ramiprilat were observed in the presence of amlodipine and atorvastatin, with Cmax ratios for ramipril and ramiprilat of 182.6% and 155.9%, and corresponding AUC0-τ ratios of 150.0% and 112.1%, respectively. These ramiprilat increases are unlikely of clinical relevance, because complete angiotensin-converting enzyme occupation is achieved with ≥5-mg ramipril doses, and free ramiprilat is rapidly eliminated. As ramipril is known to be subject to a site-dependent absorption in the upper small intestine, it is hypothesized that slowing of intestinal motility by atorvastatin or amlodipine or a combined effect of both, increased the residence time of ramipril in its "absorption window," thereby enhancing its bioavailability.

Safety of Candesartan, Amlodipine, and Atorvastatin in Combination: Interaction Study in Healthy Subjects.

For efficient cardiovascular risk protection antihypertensive treatment is often combined with cholesterol-lowering treatment, although solid data of interaction and side effects are missing. This is a prospective, single-center interaction study conducted in a fixed sequence design at steady state of candesartan, amlodipine, and atorvastatin. Five-day monotherapy of candesartan 8 mg was followed by 5-day atorvastatin 40 mg monotherapy and subsequently 9-day amlodipine 5 mg monotherapy; each treatment separated by washout phases. Immediately after amlodipine monotherapy, all 3 drugs were administered concomitantly for 5 days. Pharmacokinetic parameters as well as safety were assessed. Eighteen healthy subjects enrolled and completed the study. No significant difference in the maximum concentration (Cmax ) and the area the under plasma concentration-time curve (AUC) for amlodipine and AUC of atorvastatin was detected following combination versus monotherapy. Cmax of atorvastatin decreased slightly but clinically not relevantly when given in combination. A statistically significant but not below 0.80-fold decrease between candesartan following combination vs monotherapy was detected for Cmax and AUC. In general, all treatments were well tolerated. Concluding, systemic exposure of candesartan, amlodipine, and atorvastatin is not clinically significantly changed upon coadministration. These data support a fixed-dose combination of the 3 components for dual cardiovascular risk prevention.

Relative bioavailability of prasugrel free base in comparison to prasugrel hydrochloride in the presence and in the absence of a proton pump inhibitor.

Prasugrel (CAS 150322-43-3), an inhibitor of platelet activation and aggregation, is indicated to reduce the rate of thrombotic cardiovascular events in patients with acute coronary syndrome. If a proton pump inhibitor is co-administered with prasugrel, a pH dependent salt-to-base conversion rate of prasugrel could become clinically meaningful. In an open-label, randomized, four-period, 2 x two-way crossover study, the relative bioavailability of tablets containing prasugrel free base compared to prasugrel hydrochloride (originator product) both in the presence and in the absence of the proton pump inhibitor lansoprazole (CAS 103577-45-3) was investigated. In the absence of lansoprazole, the extent of absorption (AUC) of prasugrel free base was about 8-9% lower, while the rate of absorption (Cmax) after administration of prasugrel free base was 20% lower when compared to prasugrel hydrochloride. When lansoprazole was used to raise the pH level in the upper gastro-intestinal tract, AUC was decreased by 25% after administration of prasugrel hydrochloride and by 41% after prasugrel free base. In addition, the peak plasma levels were decreased by 52% and 72%, respectively (geometric means). The relative bioavailability of the prasugrel free base compared to prasugrel hydrochloride, both in the presence and in the absence of the proton pump inhibitor lansoprazole, differs so much that most probably a generic formulation containing prasugrel free base will not be equivalent in all aspects to the originator product.

Bioequivalence of exemestane in post-menopausal females.

The bioavailability of two exemestane tablet formulations was compared in 74 healthy post-menopausal females, aged 46 to 74 years, during a laboratory-blind, randomized, two-treatment, two-period, cross-over study under fed conditions. In each treatment phase subjects received a single dose (one tablet) of 25 mg exemestane (CAS 107868-30-4). Consecutive dosing was separated by a drug-free washout period of 21 d. Following each dosing, serial venous blood samples were collected over a period of 144 h for the determination of plasma exemestane concentrations by means of a validated LC-MS/MS method. The geometric mean Cmax of exemestane for the reference and test products was 21.48 and 20.14 ng/mL, respectively. The corresponding mean AUC(0-infinity) was 87.12 and 86.90 ng x h/mL. The median Tmax for both products under investigation appeared at 1.70 and 1.97 h, respectively. The test product was well tolerated and shown to be bioequivalent to the reference product with respect to all primary pharmacokinetic variables investigated.

Proof of systemic safety of a lidocaine ointment in the treatment of patients with anorectal pain.

OBJECTIVE: The aim of the study was to demonstrate that repeated anorectal administration of a 5% lidocaine ointment (CAS 137-58-6; LidoPosterine Salbe, Posterisan akut Rektalsalbe) in the treatment of patients with acute anorectal pain does not result in systemically efficacious plasma concentrations of lidocaine. PATIENTS AND METHODS: In an open single-center study 24 male or female patients with anorectal pain due to hemorrhoids, anal fissures, fistulas or proctitis administered lidocaine ointment as a single anorectal dose (2.5 g ointment corresponding to 125 mg lidocaine) followed by repeated administration (2.5 g ointment t.i.d.) for 4 days. Safety evaluation was performed with respect to plasma concentrations of lidocaine, vital signs, electrocardiogram (ECG), physical findings and adverse events. Blood samples were drawn prior to the first single administration and at 13 time points over the first 24 h in order to create a pharmacokinetic profile. Blood samples were also drawn prior to administration of the last dose on day 5 and thereafter using the identical time points for blood sampling as on day 1. Vital signs and ECG were recorded immediately before and 1 and 4 h after the first and last administration, respectively. Adverse events and skin tolerability were also recorded at predefined times during the study period. RESULTS: After a single dose of 125 mg lidocaine the average extent of exposure in terms of the AUC(tau,sd) during a 6 h dosage interval amounted to 397.7 ng/ml x h (geometric mean). C(max,sd) reached a mean value of 131.8 ng/ml (geometric mean). Only a minor accumulation of the lidocaine plasma concentrations was observed after multiple dose application. The geometric mean of the AUC(tau,md) (503.8 ng/ml x h, tau = 6 h) and the geometric mean of C(max,md) (145.9 ng/ml) were slightly higher than the corresponding single dose values. The AUC accumulation ratio was calculated as 127% (90% CI: 108-148%) and the C(max) accumulation ratio reached 120% (90% CI: 101-139%). Plasma peak concentrations of lidocaine in all subjects remained with a sufficient safety margin below the minimal effective therapeutic plasma concentration (1.5 microg/ml) as well as by an order of magnitude below toxic concentrations (5 microg/ml). There were neither unexpected, serious nor severe adverse events. There were no clinically relevant findings with respect to vital signs and ECG. CONCLUSIONS: Repeated anorectal administration of a 5% lidocaine ointment proved to be safe with respect to systemic plasma concentrations of lidocaine and vital signs.