Arzneimittel Forsch
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Arzneimittel Forsch · Feb 2001
Randomized Controlled Trial Clinical TrialBioequivalence study of finasteride. Determination in human plasma by high-pressure liquid chromatography coupled to tandem mass spectrometry.
Two different finasteride (CAS 98319-26-7) tablet formulations were evaluated for their relative bioavailability (Flaxin tablets 5 mg, as the test formulation vs reference formulation, tablets 5 mg) in 23 healthy male volunteers who received a single 5 mg oral dose of each preparation. The study was open, randomized with a two-period crossover design and a 7-day washout period. Plasma samples were obtained over a 48-h interval. ⋯ Geometric mean test/reference formulations individual percent ratio was 95.71 for AUC0-48 h and 88.70% for Cmax. The 90% confidence interval for the geometric mean of the individual ratio test/reference formulations was 95.70-120.20% for AUC0-48 h, 94.60-121.30 for AUC0-infinity and 88.70-108% for Cmax. Since for both Cmax or AUC the 90% Cl values are within the interval proposed by the Food and Drug Administration, the test formulation is bioequivalent to the reference formulation for both the rate and extent of absorption after single dose administration.
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Arzneimittel Forsch · Jan 2001
Randomized Controlled Trial Clinical TrialDose-related effects of controlled release dihydrocodeine on oro-cecal transit and pupillary light reflex. A study in human volunteers.
It is well accepted that long-term administration of opioids results in a dose-related constipation. No data so far have demonstrated conclusively whether such constipation is also seen after intake of a controlled release formulation. It was therefore of interest to evaluate whether increasing doses of a controlled release formulation of dihydrocodeine (DHC, CAS 125-28-0) after oral administration also induces a dose-related increase in constipation. ⋯ It is concluded that opioid receptor sites, which are located in the plexus myentericus of the intestinal wall, are responsible for the delay in propulsion. Because of the controlled release of a fixed amount of DHC over time there is constant binding of the ligand followed by a constant conformational change of peripheral and central receptor sites. Thus constant release induces no dose-related increase in oro-cecal transit and inhibition of the pupillary light reflex.
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Arzneimittel Forsch · Jan 2001
Randomized Controlled Trial Comparative Study Clinical Trial[Relative bioavailability of diclofenac after a single administration of a new multiple-unit formulation of enteric-coated pellets].
The relative bioavailability of diclofenac (CAS 15307-86-5) was investigated after a single administration of a multiple-unit formulation containing 75 mg diclofenac sodium in enteric-coated pellets (A) in comparison to an enteric-coated tablet with 50 mg diclofenac sodium (B), a capsule containing 140 mg diclofenac resinate (C) and a dispersible tablet containing 46.5 mg diclofenac acid (D). The study was carried out in a four-way crossover design in 16 healthy male volunteers. Serum concentrations of diclofenac were determined with a validated and specific HPLC-method. ⋯ Despite the enteric-coating of the pellets, a short lagtime of 0.4 h was determined for the test formulation. For the other rapid-release formulation (D), the lagtime was of a similar magnitude (0.3 h), while drug release and absorption from the enteric-coated tablet and the diclofenac resinate capsule were delayed (1.8 and 0.7 h, respectively). Due to the rapid and high bioavailability of diclofenac, the multiple-unit formulation fulfills the prerequisites for the oral treatment of acute painful conditions when prompt analgesic and anti-inflammatory efficacy is desired.
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Arzneimittel Forsch · Jan 2001
Role of L-arginine/nitric oxide pathway in the antinociceptive activities of morphine and mepyramine in mice.
The p-benzoquinone (PBQ)-induced abdominal constriction test was used to assess the involvement of L-arginine/nitric oxide (NO) pathway in the antinociceptive activity of the subcutaneously administered H1-receptor antagonist, mepyramine (CAS 59-33-6), and an opioid receptor agonist, morphine (CAS 57-27-2), in mice. Mepyramine (ED50: 5.6 mg/kg) and morphine (ED50: 0.13 mg/kg) produced antinociceptive effects. The NO precursor L-arginine (CAS 1119-34-2) (50 mg/kg) also produced antinociception similar to mepyramine, but significantly less than morphine. ⋯ The antinociceptive activity of morphine, but not that of mepyramine, was completely abolished when combined with L-NMMA. L-NMMA also significantly decreased the antinociception induced by morphine or mepyramine in combination with L-arginine. The present results suggest that morphine and mepyramine could produce peripheral antinociception by the involvement of L-arginine/NO cascade or other related pathways of nociceptive processes induced by NO.
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Arzneimittel Forsch · Jan 2001
Antioxidant effect of N omega-nitro-L-arginine methyl ester (L-NAME) on global cerebral ischemia in a rat model.
The antioxidant effect of the non-specific nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (CAS 50903-99-6, L-NAME), was studied in a rat model of global cerebral ischemia. In addition, the influence of low doses of L-NAME on nitric oxide production, measured as nitrate/nitrite end products, was investigated in the ischemic rats. Ischemia was induced by bilateral clamping of the common carotid arteries for 60 min followed by a reperfusion period for 60 min. ⋯ L-NAME was also capable to normalize the reduced activity of superoxide dismutase (SOD, 1.15.1.1) that was observed after ischemia. Improvement of these parameters in L-NAME-treated rats was parallel to normalization of nitric oxide production in the treated animals. These results indicate that inhibition of nitric oxide synthase, induced by L-NAME, could improve the oxidative status of the rat brain after ischemia.