Digoxin concentrations in serum and cantharides blister fluid: correlations with cardiac response.

The relationship between the pharmacokinetics and dynamics of digoxin was investigated using a skin blistering technique that allows experimental access to tissue fluid concentrations. Eight healthy volunteers received digoxin, 1.0 mg, and placebo intravenously according to a double-blind crossover design. Drug concentrations were determined during a 72-hour period in serum, urine, and cantharides blister fluid (CBF). Digoxin levels in the hypothetic peripheral compartments were calculated from serum concentrations. Digoxin effects (total electromechanical systole [QS2c], left ventricular ejection time [LVETc], preejection period [PEPc], QTc time, heart rate, and T wave amplitude) were measured simultaneously. Peak levels in the shallow and deep compartments occurred at 12 1/2 to 20 minutes and 3 hours and the maximum concentration in CBF (2.75 +/- 0.48 ng/ml) occurred at 1 hour. Digoxin effects on QS2c, PEPc, and the ratio PEP/LVET were not related to serum concentrations but were closely related to CBF concentrations (r = 0.90). CBF concentrations were then within the range of serum digoxin concentrations usually associated with the treatment of heart failure. Thus, CBF allows experimental access to active drug concentrations after a single intravenous dose.

Kinetics of fenoximone, a new cardiotonic, in healthy subjects.

Fenoximone, a new cardiotonic, was given to six healthy men as a single intravenous dose of 1 mg/kg and a single oral dose of 3 mg/kg as solution in a crossover study. Plasma concentrations were monitored for 8 hr and urine was collected for 24 hr. Peak plasma concentrations (Cmax) were reached 30 min after the oral dose. Decay of plasma concentrations was fitted to a mean (+/- SD) elimination t1/2 (t1/2 beta) of 60 +/- 14 min after intravenous injection and 78 +/- 26 min after oral dosing. Mean total body clearance for intravenous dosing was 2062 +/- 846 ml/min, renal clearance (ClR) was 5.3 +/- 2.4 ml/min, and extrapolated volume of distribution was 0.37 +/- 0.26 l/kg. The sulfoxide derivative was detected as the main metabolite. Cmax of the sulfoxide metabolite occurred 10 min after the end of the intravenous infusion and 20 to 60 min after oral dosing. From the decay of the plasma concentrations of the sulfoxide, the t1/2 beta s were calculated as 132 +/- 15 min after intravenous injection and 140 +/- 27 min after oral dosing of fenoximone. ClR of the sulfoxide was 499 +/- 106 ml/min after intravenous injection; 24-hr urinary recovery of the sulfoxide was 75.7% +/- 5.7% after intravenous injection and 64.3% +/- 10.4% after oral dosing. Mean oral bioavailability of fenoximone was 53% (range 44% to 69%).

Kinetics of alpha-difluoromethylornithine: an irreversible inhibitor of ornithine decarboxylase.

We gave alpha-difluoromethylornithine (DFMO), a selective, irreversible inhibitor of ornithine decarboxylase, to six health men in single intravenous doses of 5 and 10 mg/kg body weight and oral doses of 10 and 20 mg/kg. Plasma concentrations were monitored during the 24 hr after each dose. Urine was collected from 0 to 24 hr after drug and amount of unchanged drug excreted was determined. Peak plasma concentrations were reached within 6 hr after oral doses. The decay of the plasma concentrations followed first-order kinetics with a mean half-life (t 1/2) for all four doses studied of 199 +/- 6 min (+/- SD). Mean total body clearance (ClT) for the four doses was 1.20 +/- 0.06 ml . min-1 . kg-1. Mean renal clearance was determined as 0.99 +/- 0.03 ml . min-1 . kg-1, accounting for 83% of drug elimination. Mean apparent volume of distribution (aVD) was 0.337 +/- 0.031 l/kg-1, corresponding to 24 l for 70 kg of body weight. The amount of unchanged drug in 24-hr urine samples was 47 +/- 7% and 40 +/- 11% after 10 and 20 mg/kg orally, and 78% and 81 +/- 8% after 5 and 10 mg/kg intravenously. Bioavailability of the 10 mg/kg dose was estimated as 58% from the urinary recoveries and as 54% from the areas under the plasma concentration curves (AUC 0 leads to infinity). Since doubling of the dose resulted in a doubling of the mean AUC 0 leads to infinity and since other kinetic parameters, such as aVD, t 1/2, ClT, and the urinary recovery of unchanged drug, were essentially the same at all doses, DFMO kinetics follow a dose-linear model.

Kinetics of medroxalol, a beta- and alpha-adrenoceptor antagonist.

Eight healthy men received single oral doses of 400, 800, and 1200 mg medroxalol and a single intravenous dose of 1 mg per kg body weight on four occasions separated by at least 2 wk. Plasma medroxalol concentrations were assayed up to 24 hr after each dose by a specific high-pressure liquid chromatographic assay. Urinary excretion of parent compound was determined as well. Following oral doses medroxalol reached peak plasma concentrations within 2.5 to 3 hr. The t 1/2 of the terminal decay phase was 11.1 hr. Mean apparent volume of distribution (aVD) was between 11.2 and 16.4 l/kg, and mean total body clearance (ClT) was between 0.73 and 0.99 l hr-1 kg-1. Mean urinary recovery of parent drug within 48 hr was 2.3%, 3.9%, and 3.6% after the oral doses compared to 8.2% after the intravenous dose. Bioavailability estimated from AUC was 27.2% after 400 mg, 31.3% after 800 mg, and 37.4% after 1200 mg by mouth. Since aVD, t 1/2, ClT, and urinary excretion did not differ significantly after the three oral doses, medroxalol kinetics appear to follow a dose-linear model.

Efficacy and tolerance of repeated oral doses of tolperisone hydrochloride in the treatment of painful reflex muscle spasm: results of a prospective placebo-controlled double-blind trial.

The efficacy and safety of oral tolperisone hydrochloride (Mydocalm) in the treatment of painful reflex muscle spasm was assessed in a prospective, randomized, double-blind, placebo-controlled trial. A total of 138 patients, aged between 20 and 75 years, with painful reflex muscle spasm associated with diseases of the spinal column or proximal joints were enrolled in eight rehabilitation centers. Patients were randomized to receive either 300 mg tolperisone hydrochloride or placebo for a period of 21 days. Both treatment groups recovered during the 3 weeks rehabilitation program. However, tolperisone hydrochloride proved to be significantly superior to placebo: the change score of the pressure pain threshold as the primary target parameter significantly increased during therapy with tolperisone hydrochloride (P = 0.03, valid-case-analysis) compared to the results obtained on placebo treatment. The overall assessment of efficacy by the patient also demonstrated significant differences in favor of tolperisone hydrochloride. Best results were seen in patients aged between 40 and 60 years with a history of complaints shorter than 1 year and with concomitant physical therapy. The evaluation of safety data, i.e., adverse events, biochemical and hematological laboratory parameters, demonstrated no differences between tolperisone hydrochloride and placebo. As a conclusion tolperisone hydrochloride represents an effective and safe treatment of painful reflex muscle spasm without the typical side effects of centrally active muscle relaxants.

Evaluation of the efficacy of a combined formulation (Grippostad-C) in the therapy of symptoms of common cold: a randomized, double-blind, multicenter trial.

BACKGROUND: The aim of the present trial was to evaluate the efficacy of a combined product in the treatment of common cold and to examine the contribution of the separate components. In the published literature there is conflicting data on the efficacy of agents used in the treatment of common cold, especially when given in drug combinations. METHODS: A prospective, randomized, double-blind, multicenter, 4-arm, controlled trial was carried out in 1,167 patients with common cold treated with one of the following medications: Grippostad-C, a combination of acetaminophen, caffeine, chlorpheniramine and ascorbic acid (verum), ascorbic acid (control), chlorpheniramine and ascorbic acid (reference 1), as well as acetaminophen, caffeine, and ascorbic acid (reference 2). A score of common cold symptoms (headache, throat pain, extremities and joint pain, cough, blocked nose, and disturbances of sleep quality) was the primary outcome. The test drug was first compared with the control using a hierarchic test strategy, then with reference 1, followed by reference 2 with the aim of proving superiority. FINDINGS: A clinically relevant and statistically significant difference was demonstrated at each level of the hierarchy. Grippostad-C was significantly superior to all other treatment groups, the combination of acetaminophen, caffeine, and ascorbic acid was significantly superior to the control, and the combination of chlorpheniramine and ascorbic acid was not statistically different from the control. INTERPRETATION: The efficacy of Grippostad-C for the treatment of common cold was proven. The findings demonstrate that the combination is superior to each of its separate components and each of the components has its own distinctive contribution to the efficacy of the combination product.

[Clinical and urodynamic effects of oral propiverine therapy in neurogenic urinary incontinence. A multicenter study for optimizing dosage]. / Klinische und urodynamische Effekte einer oralen Propiverintherapie bei neurogener Harninkontinenz. Eine multizentrische Studie zur Dosisoptimierung.

The efficacy and tolerability of propiverine hydrochloride (in doses of 15, 30, 45 and 60 mg/day) were evaluated in the treatment of 66 patients suffering from neurogenic incontinence for 21 days in an open, randomized, multicentre, parallel-group trial. Evaluation of efficacy was based on changes in cystometry, flow measurements and micturition and that of safety on adverse reactions and blood chemistry. The bladder volume increased and bladder pressure decreased dose dependently; the ratio of the two increased by 0.6, 3.3, 3.8 and 8.1 ml/cm H2O after 15, 30, 45 and 60 mg/day respectively. Some 54% of patients had a decreased micturition frequency after 15 mg/day and about 80% after 30-60 mg/day. At the same time, 8, 35, 12 and 42% of patients had subjective anticholinergic symptoms after therapy with 15, 30, 45 and 60 mg/day, respectively. The results suggest that propiverine is a safe and effective drug for the treatment of neurogenic incontinence. A daily dose of 30 mg propiverine is recommended; individual adjustment of the maintenance dose to 15 or 45 mg/day may be necessary.

A comparative dose-effect study with cardiac glycosides assessing cardiac and extracardiac responses in normal subjects.

We tested the hypothesis that differences exist in the pharmacodynamic pattern of different cardiac glycosides. We conducted a randomized, placebo-controlled study in normal volunteers and evaluated the effects of weekly increased oral dosing of digoxin (n = 10; from 0.25 to 1.0 mg/day), meproscillarin (n = 10; from 0.5 to 2.0 mg/day), and placebo (n = 5). To determine the glycoside effects, corrected electromechanical systole (QS2c) was used to measure inotropy and the PQ interval to test dromotropy. Red-green discrimination and critical flicker fusion (CFF) assessed visual functions. Subjective complaints were collected using rating lists. Both glycosides dose dependently shortened QS2c and prolonged PQ interval. PQ prolongations over +20 ms occurred in seven of 10 digoxin subjects, in two of 10 meproscillarin, and in one of five placebo. Equi-inotropic response, identified at 12 ms mean QS2c shortening, revealed the relative potency of digoxin to be 2.4 times higher than meproscillarin; this ratio increased to sevenfold for equi-effective negative dromotropic effects at 12 ms mean PQ prolongation. Each drug was associated with a dominant subjective complaint: digoxin with anergy and meproscillarin with diarrhea. Red-green discrimination was better under meproscillarin and CFF was depressed by digoxin. The results indicate that pharmacodynamic differences exist between cardiac glycosides. A differential use of various glycosides should be considered and tested clinically.

Color vision deficiencies: a common sign of intoxication in chronically digoxin-treated patients.

On the basis of anamnestic data from digitalis-intoxicated patients, rates of general disorders of vision between 6 and 20% have been reported. We used a psychophysical method, an automatically evaluated Farnsworth's Munsell 100-Hue Test, to detect color vision deficiencies in patients who received beta-methyldigoxin or beta-acetyldigoxin for at least 4 weeks as maintenance therapy. Patients were subgrouped according to serum digoxin concentrations measured by radioimmunoassay. There was a significant correlation between extent and rate of color vision deficiencies and serum digoxin concentrations. About 80% of the intoxicated patients showed generalized color vision deficiencies.

[Disorders of the ability to distinguish colors during digitalis therapy (author's transl)]. / Störungen des Farbunterscheidungs- vermögens unter Digitalistherapie.

31 hospitalized patients treated with beta-methyl digoxin and 34 treated with beta-acetyl digoxin were examined for color vision disturbances and compared with a control group (n = 17). The serum digoxin concentration was determined radioimmunologically. A significant correlation (p less than 0,01) was found between the severeness of the disturbances in color vision and the concentration of digoxin in the serum. The disturbances concerned different wave length regions. The lapse of time for disturbances in the distinguishing colors is being described in a case of suicidal intoxication.

Absolute bioavailability of oral immediate and slow release fluphenazine in healthy volunteers.

OBJECTIVE: The present study was conducted with the aim of investigating the absolute bioavailability of fluphenazine in healthy volunteers after administration of immediate and slow release oral formulations. METHODS: The oral dose was 12 mg fluphenazine hydrochloride. The intravenous bolus dose was 2.5 mg. Fourteen healthy volunteers of both sexes were enrolled in this randomised, crossover trial. Twelve volunteers completed the trial according to protocol. RESULTS: The concentration maxima after administration of the slow release formulation were approximately half those measured after the immediate release formulation and were recorded later by a factor of 2 (immediate release: Cmax = 2.3 ng.ml-1, tmax = 2.8 h; slow release: Cmax = 1.2 ng.ml-1, tmax = 4.6 h). The concentrations measured 10 min after intravenous bolus administration of 2.5 mg fluphenazine hydrochloride were approximately 100 times higher (261 ng.ml-1). The geometric means for the absolute bioavailability of fluphenazine were 2.7% for the immediate release formulation and 3.4% for the slow release formulation. The absolute bioavailability of fluphenazine is thus much lower than previously generally accepted.

Serum concentration of piroxicam and inhibition of platelet aggregation in patients with rheumatoid arthritis and M. Bechterew.

An open trial was conducted in 22 in-patients with classic or definite rheumatoid arthritis (RA) and 17 in-patients with M. Bechterew with the aim to investigate the effect of increasing concentrations of piroxicam in vivo on the platelet aggregation in such patients. In all patients therapy with piroxicam (10 mg/d) was started after withdrawing other non-steroidal antiinflammatory drugs. In 36 cases the daily dose of piroxicam was increased to 20 mg/d and in five cases to 30 mg/d based on clinical judgment. The platelet aggregation in platelet-rich plasma (PRP) caused by epinephrine, ADP (both 5 microM) and collagen (2 micrograms/ml) was measured at the beginning of the trial and before each dose increase. The results of the trial suggest that a significant positive correlation exists between increasing serum concentrations of piroxicam and the degree of inhibition of platelet aggregation, caused by all three platelet aggregation agonists. This action of piroxicam was most pronounced when epinephrine was used as platelet agonist.

Effect of diprafenone on the pharmacokinetics of digoxin.

This study was conducted to investigate the effect of diprafenone on the steady-state pharmacokinetics of digoxin. Twelve healthy men, all rapid hydroxylators of debrisoquine, received digoxin (0.5 mg per day over 7 days with a loading dose of 2 x 1 mg) or digoxin and diprafenone (3 x 100 mg per day) in three different phases, without a wash-out period (phase 1, digoxin alone; phase 2, digoxin + diprafenone; phase 3, digoxin alone). Blood and urine samples were collected for pharmacokinetic analyses. Diprafenone caused a statistically significant increase in digoxin trough concentrations [1.4 (SD 0.2) vs 1.6 (0.3) ng.ml-1], AUC(zero)-24 values [41 (7) vs 48 (9) ng.h.ml-1 and Css-max[3.9 (0.6) vs 5.5 (0.9) ng.ml-1]. In all volunteers the parameters tended to return to the original values after administration of diprafenone was discontinued [1.4 (0.3) ng.ml-1, 39 (11) ng.h.ml-1, and 3.9 (1.1) ng.ml-1 for trough concentration, AUC(zero)-24 and Cmax respectively]. The mean relative magnitude of the increase in AUC(zero)-24 and trough concentration values corresponded to the mean relative decrease in the renal clearance of digoxin (in both cases approximately 20%). This suggests that the increase in AUC and Css was caused by reduced renal clearance of digoxin.

[Comparative study of the absolute bioavailability of four oral digoxin preparations (author's transl)]. / Vergleichende Untersuchung der absoluten Bioverfügbarkeit von vier oralen Digoxin-Präparaten.

In a randomized cross over study on 19 normal subjects the absolute bioavailability of four oral digoxin preparations (Digacin containing a silica gel matrix as preparation A and three other commercial digoxin tablet preparations, B, C and D) were investigated applying digoxin in a daily dose of 0.25 mg for 10 consecutive days. On day 8, 9 and 10, the serum digoxin concentration and the amount of digoxin excreted with 24-h urine were measured radioimmunologically. After i.v. administration the mean serum digoxin concentration amounted to 0.58 ng/ml. With oral administration preparation A achieved the highest concentration (0.51 ng/ml) and preparation C the lowest (0.42 ng/ml). Accordingly, after i.v. administration 118 microgram digoxin were excreted with the 24-h urine and 95 microgram after the oral preparation A and 73 microgram after preparation C, respectively. From the serum concentrations and the amount excreted with the urine the absolute bioavailability was calculated: 88.0 and 80.4%, respectively, for preparation A, 82.5 and 67.2% for preparation B, 72.7 and 61.8% for preparation C, 76.2 and 67.3% for preparation D.

Balm mint extract (Lo-701) for topical treatment of recurring herpes labialis.

A double-blind, placebo-controlled, randomized trial was carried out with the aim of proving efficacy of standardized balm mint cream [active ingredient: 1% Lo-701--dried extract from Melissa officinalis L. leaves (70:1)] for the therapy of herpes simplex labialis. Sixty six patients with a history of recurrent herpes labialis (at least four episodes per year) in one center were treated topically; 34 of them with verum and 32 with placebo. The cream had to be smeared on the affected area four times daily over five days. A combined symptom score of the values for complaints, size of affected area and blisters at day 2 of therapy was formed as the primary target parameter. There was a significant difference in the values of the primary target parameter between both treatment groups: verum 4.03 +/- 0.33 (3.0); placebo 4.94 +/- 0.40 (5.0); values given are mean +/- SEM (median) of the symptoms score on day 2 of therapy. The tested formulation is effective for the treatment of herpes simplex labialis. The significant difference in the combined symptom score on the second day of treatment is of particular importance having in mind that the complaints in patients suffering from herpes labialis are usually most intensive at that time. In addition to the shortening of the healing period, the prevention of a spreading of the infection and the rapid effect on typical symptoms of herpes like itching, tingling, burning, stabbing, swelling, tautness and erythema, the balm mint cream has a further advantage. The different mechanism of action of the balm mint extract rules out the development of resistance of the herpes virus. Some indication exists that the intervals between the periods with herpes might be prolonged with balm mint cream treatment.