Biomedical subjects

S Antila

Publications and source records attributed to S Antila.

16 recordsLinked to original sources

PubMed2003

Pharmacokinetic-pharmacodynamic interrelationships of intravenous and oral levosimendan in patients with severe congestive heart failure.

OBJECTIVE: To assess the pharmacokinetic-pharmacodynamic (PK-PD) interrelations after a 6-hour continuous infusion and a 2 mg single oral dose of levosimendan in patients with congestive heart failure (CHF). METHODS: This was an open-label, non-randomized Phase II trial in 29 patients with New York Heart Association (NYHA) class III-IV CHF, comprising 2 study days. On the first day, patients were given 6-hour levosimendan infusion with the dose 0.2 microg/kg/min. After a 1-week washout, the patients received a 2 mg single oral dose of levosimendan. Heart rate-corrected electromechanical systole QS2i was the primary variable. Secondary variables were heart rate (HR), systolic (sBP) and diastolic blood pressure (dBP) and 24-hour ambulatory ECG (Holter). RESULTS: QS2i shortened from 515 ms at baseline to 506 ms at the end of 6-hour infusion (p = 0.007). After 2 mg single dose, QS2i shortened at 2 h after drug intake from 532 ms at baseline to 525 ms (p = 0.006). The effect was similar also at 8 h (532 ms vs 526 ms, p = 0.017). Mean of maximum shortening of QS2i observed during the infusion was 22 ms (p < 0.0001) and 17 ms after 2 mg single oral dose (p < 0.0001). The concentration-effect loops for QS2i showed a clear counter-clockwise hysteresis with both modes of administration. sBP and dBP decreased both during infusion and after 2 mg oral dose. HR remained unchanged during both modes of administration. CONCLUSIONS: Both 6-hour infusion and 2 mg single dose of levosimendan showed that levosimendan possesses moderate inotropic and vasodilatory effects in patients with severe congestive heart failure, which could be described as counter-clockwise hysteresis. It seemed that the vasodilatory effect appeared earlier than the inotropic effect.

Administration, Oral↗

PubMed2002

Development of level A, B and C in vitro-in vivo correlations for modified-release levosimendan capsules.

The aim of this study was to investigate the possibility of developing different levels of correlation between in vitro release and in vivo absorption rate for four modified-release levosimendan capsule formulations. Differences and similarities in the in vitro dissolution curves were compared with pharmacokinetic parameters describing absorption rate. Formulations F, G, H and I differed in the amounts of the delaying excipients alginic acid and HPMC. In vitro release rate was studied by the USP basket method using the following conditions: pH 5.8 or 7.4 and a rotation speed of 50 or 100 rpm. In vivo bioavailability was tested in nine healthy male volunteers and the fractions absorbed were calculated by the Wagner-Nelson method. Dissolution conditions pH 5.8 and a rotation speed of 100 rpm predicted best the similarities and differences in absorption rates among different formulations, and levels C and B correlation coefficients were 0.85 and 0.97, respectively. For formulation H level A correlation (r=0.997) was found when in vitro lag time was 0.2 h and time scale factor 1.9. This study indicated that dissolution tests developed can be used as a surrogate for human bioequivalence studies, for development processes of final commercial products, to ensure batch to batch bioequivalence and in the future in possible scale-up and post approval change cases for modified-release levosimendan formulation H.

Adult↗

PubMed2002

Pharmacokinetics of levosimendan and its metabolites during and after a 24-hour continuous infusion in patients with severe heart failure.

OBJECTIVE: Levosimendan is a new calcium sensitizer with additional vasodilatory properties developed for the short-term intravenous treatment of congestive heart failure. The aims of the present study were to determine the pharmacokinetics and hemodynamic effects of levosimendan and its metabolites during and after a 24-hour levosimendan infusion. METHODS: The study was an open-label, non-randomized, phase II study in 2 centers. Twelve patients with NYHA III-IV heart failure received 0.2 microg/kg/min continuous infusion of levosimendan for 24 hours. Blood samples for the determination of plasma concentrations of the parent drug and the metabolites were drawn repeatedly during the infusion and the 2-week follow-up period. Heart rate from Holter recordings and blood pressure were measured. RESULTS: The elimination half-life of levosimendan was 1.3 hours and that of the metabolites 75-78 hours. The mean maximum increase in heart rate of 10 bpm (p < 0.005) and the mean maximum decreases in systolic and diastolic blood pressure of 12 mmHg and 8 mmHg (p < 0.05 for both), respectively, were observed during the first day after stopping levosimendan infusion. The hemodynamic effects slowly declined during the follow-up, and after 1 week no statistically significant differences compared with baseline were observed. No increase in ventricular arrhythmias was seen. CONCLUSION: A 24-hour infusion of levosimendan induces hemodynamic effects lasting several days after stopping the infusion. The prolongation of the effects beyond the infusion period is most likely due to an active metabolite with a long half-life.

Blood Pressure↗

PubMed2001

Mismatch negativity is unaffected by top-down predictive information.

The mismatch negativity (MMN) event-related brain potential is assumed to reflect a stimulus-driven change detection process. We examined whether MMN is sensitive to volitional control by testing whether MMN is affected by the subject's foreknowledge of the sound changes. Subjects were instructed to produce a sequence of button presses by pressing one button frequently and another infrequently. In the predictable condition, the frequently pressed button triggered the standard tone, the other button the deviant tone. In the unpredictable condition, each button press triggered the next tone of a prearranged standard/deviant sequence. No difference was found in the MMN amplitude, latency, or scalp distribution between the predictable and unpredictable conditions. This suggests that there is no direct top-down control over the MMN-generating process.

Acoustic Stimulation↗

PubMed2000

Pharmacokinetic and pharmacodynamic interactions between the novel calcium sensitiser levosimendan and warfarin.

OBJECTIVE: To study the effects of possible interactions between levosimendan and warfarin on pharmacokinetics and pharmacodynamics. Furthermore, the effects of levosimendan on blood coagulation were investigated. METHODS: Open, randomised cross-over design with two treatment phases was used. During one phase, levosimendan (0.5 mg four times daily) was given orally to ten healthy subjects for 9 days. On the fourth treatment day with levosimendan, a single oral dose of warfarin (25 mg) was given. Pharmacokinetic parameters of levosimendan from the third and fourth treatment days were compared with each other. During the other treatment phase the subjects received only a single dose of warfarin. Pharmacokinetic parameters of warfarin alone were compared with those determined after concomitant administration of levosimendan. Changes in blood coagulation parameters were evaluated after levosimendan and warfarin alone and after concomitant administration. RESULTS: Warfarin did not change the pharmacokinetics of levosimendan. The distribution volume of warfarin was higher and elimination half-life shorter after concomitant levosimendan administration than after warfarin alone. However, concomitant levosimendan administration did not potentiate the effects of warfarin on blood coagulation assessed using activated partial thromboplastin time (APTT) and thromboplastin time (TT-SPA). Levosimendan alone for 3 days did not change APTT or TT-SPA values. There were no changes in the protein binding of levosimendan or warfarin upon concomitant administration. Continuous treatment with oral levosimendan caused headache, which was probably due to cerebral vasodilation. CONCLUSIONS: Concomitant levosimendan administration did not potentiate the effect of warfarin on blood coagulation after a single dose. Levosimendan itself had no effects on blood coagulation.

Adult↗

PubMed2000

Transdermal delivery of levosimendan.

The aim of this study was to determine if transdermal penetration of levosimendan, a novel positive inotropic drug, could be enhanced and controlled by formulation modifications. Penetration of levosimendan across human epidermis in vitro was determined using abdominal excised skin and diffusion cells. Predicted steady-state plasma concentrations of levosimendan were estimated using permeabilities and pharmacokinetic parameters of levosimendan. For penetration enhancement we used different pH values, co-solvents, cyclodextrins, surfactants, penetration enhancers, liposomes, and iontophoresis. Sodium lauryl sulfate, ethanol, oleic acid, and soya phosphatidylcholine or their combinations clearly increased levosimendan permeation across the skin in vitro. Iontophoresis was also an efficient method to increase transdermal permeation of levosimendan. A hydrophilic co-solvent/penetration enhancer is needed to achieve better permeability of levosimendan across the skin. In conclusion, transdermal delivery of levosimendan can be significantly increased by formulation modification. Based on kinetic calculations, therapeutic plasma concentrations may be achievable transdermally.

Administration, Cutaneous↗

PubMed1999

Site dependent bioavailability and metabolism of levosimendan in dogs.

Site specific bioavailability and metabolism of levosimendan was studied in ten dogs by placing intestinal access port catheters in different parts of the gastrointestinal tract. 14C-labelled levosimendan (0.1 mg/kg) was administered intravenously, by gastric tube and directly through catheters that were placed in the duodenum, jejunum and ileum. Plasma samples were collected and radioactivity in the different organs and tissues was measured. The results of the present study showed that bioavailability of levosimendan was high varying from 71 to 86% after extravascular administration. Metabolite OR-1855 concentrations in the plasma were about 3-4 times higher after administration to the ileum compared to the other administration routes. It can be concluded that the bioavailability of levosimendan is not affected by site specific administration. The bacteria or enzymes responsible for the metabolism of levosimendan are located in the lower parts of the gastrointestinal tract.

Animals↗

PubMed1998

The CYP3A4 inhibitor intraconazole does not affect the pharmacokinetics of a new calcium-sensitizing drug levosimendan.

Itraconazole is a potent inhibitor of CYP3A4 isoenzyme and it can cause clinically significant interactions with some other drugs. Levosimendan is a new calcium-sensitizing drug intended for congestive heart failure. We aimed to study possible interactions of itraconazole with levosimendan in healthy volunteers. Twelve healthy male volunteers were included into a randomized, double-blind, two-phase crossover study. A wash-out period of 4 weeks was held between the phases. The subjects were given orally itraconazole 200 mg or placebo daily for 5 days. On the fifth day, they received a single oral dose of 2 mg of levosimendan. Levosimendan plasma concentrations were determined up to 12 hours and ECG, heart rate, and blood pressure followed-up to 8 hours after intake of levosimendan. Itraconazole had no significant effects on the pharmacokinetic parameters of levosimendan. Neither were there any differences in heart rate, PQ-, QTc- or QRS intervals between the placebo and itraconazole phases. The systolic blood pressure was decreased slightly more (p < 0.05) during the itraconazole phase than during the placebo phase. In conclusion, because the potent CYP3A4 inhibitor itraconazole had no significant pharmacokinetic interaction with levosimendan, interactions with CYP3A4 inhibitor, and oral levosimendan are unlikely.

Adult↗

PubMed1998

Integrated pharmacokinetics and pharmacodynamics of the novel calcium sensitizer levosimendan as assessed by systolic time intervals.

BACKGROUND: Levosimendan is a new calcium sensitizer, acting calcium-dependently on cardiac troponin C. In the present study pharmacokinetic-pharmacodynamic interrelations of levosimendan were assessed. SUBJECTS AND METHODS: Ten healthy subjects (22-27 years) were given single doses of 2 mg of levosimendan in 4 different formulations: intravenous (i.v.), conventional tablet (CT), conventional capsule (CC), and slow-release tablet (SR) on different days. Systolic time intervals and impedance cardiography were recorded up to 4 hours post drug. Plasma concentrations of levosimendan and its metabolite OR-1855 were analyzed using HPLC. Hysteresis loops were constructed by connecting the effect-concentration points in time order. In addition, pharmacokinetic-pharmacodynamic modelling was performed with the i.v. data. RESULTS: The i.v. administration, giving a maximal levosimendan concentration of 180 ng x ml(-1), increased heart rate by 8 beats min(-1) and cardiac output by 18%. It shortened heart rate corrected electromechanical systole QS2i by 23 ms, indicating a fairly strong positive inotropic effect. The conventional oral formulations (giving maximal drug concentrations of about 70-80 ng x ml(-1)) increased heart rate by 4-5 beats min(-1) and cardiac output by 5-8%, while QS2i shortened by 9-13 ms. The SR formulation resulted in low drug concentrations and generally weaker effects than the other formulations. The bioavailability of CT and CC was 83 and 87%, while that of SR was only 31%. QS2i showed counter-clockwise hysteresis after all formulations (p < 0.01). The mean equilibration half-time (ln(2)/k(e0)) after i.v. administration was 9.6 min. Only after SR, OR-1855 was detected in appreciable amounts in plasma, the highest value being 2.2 ng x ml(-1) which occurred 24 hours after drug intake. CONCLUSION: In conclusion, the pharmacokinetic-dynamic behavior of the inotropy index QS2i indicates an equilibration delay of levosimendan, which most probably reflects the time the drug requires to distribute from plasma to its cardiac site of action. The deviant kinetic-dynamic profile of the oral slow-release formulation suggests a different absorption pattern of levosimendan from this formulation.

Administration, Oral↗

PubMed1997

Studies on psychomotoric effects and pharmacokinetic interactions of the new calcium sensitizing drug levosimendan and ethanol.

Levosimendan (CAS 141505-33-1) is a calcium sensitizing drug intended for the treatment of congestive heart failure. In animal experiments levosimendan has potentiated the sedative effects of ethanol. Due to poor water solubility of the compound, ethanol is used as a diluent in the intravenous formulation. In this study the possible interactions between levosimendan and ethanol in human have been studied. Twelve healthy male volunteers were included in this double-blind, randomized, cross-over study. The study consisted of three treatment periods: levosimendan 1 mg intravenously, levosimendan combined with ethanol orally and ethanol 0.8 g/kg alone. Blood samples for determination of levosimendan and ethanol concentrations were collected for 8 h after the dosing. To observe possible pharmacodynamic interactions psychomotoric tests were made before drug administration and 1h, 2h, 3h and 6h thereafter. These tests included Digit symbol substitution test, Maddox wing, Critical Flicker fusion and VAS-test for subjective assessment of performance status. Plasma levosimendan concentrations were not changed by the concomitant ethanol administration. Ethanol did not alter the pharmacokinetics of levosimendan except the volume of distribution of central compartment which was decreased. Levosimendan did neither affect elimination of ethanol. Levosimendan did not potentiate the psychomotoric effects of ethanol neither did it have any psychomotoric effects itself. In conclusion, levosimendan is not likely to have any psychomotoric adverse effects or any clinically significant interactions with ethanol.

Adult↗

PubMed1996

Haemodynamic interactions of a new calcium sensitizing drug levosimendan and captopril.

OBJECTIVE: Levosimendan in a new inodilator drug that sensitizes troponin C in heart muscle cells to calcium, thus improving contractility. In previous studies, a single 2 mg intravenous dose of levosimendan increased cardiac output (CO) in healthy volunteers by about 40% and decreased pulmonary capillary wedge pressure in heart failure patients by 40-50%. The aim of the present, double-blind study was to evaluate the safety of concomitant use of levosimendan and an ACE-inhibiting drug. METHODS: The haemodynamic effects of levosimendan, given with or without captopril, were evaluated by using 2-dimensional echocardiography, repeated blood pressure measurements and by ambulatory ECG recordings. Twenty-four male patients with stable NYHA II-III heart failure (EF < 40%) after a previous myocardial infarct were given, in randomised order, a single i.v. infusion of levosimendan or placebo. The infusions were repeated after 2 weeks treatment with upto 50 mg b.i.d. of captopril. Twelve patients received levosimendan 1 mg and twelve received 2 mg. RESULTS: Mean CO was increased from 6.0 to 6.8 1 . min-1 in patients receiving 1 mg levosimendan compared to placebo, but only from 6.3 to 6.5 1 . min-1 in patients receiving 2 mg. The increase in CO was statistically significant when all levosimendan patients were compared to placebo. Heart rate did not change after either dose. Mean stroke volume increased significantly after 1 mg but not after 2 mg of levosimendan. The addition of captopril did not change the effects of levosimendan. No additional decrease in systolic or diastolic blood pressure was observed when levosimendan and captopril were given concomitantly. CONCLUSION: It seems that concomitant treatment with captopril does not change the haemodynamic effects of levosimendan. No adverse haemodynamic interactions were seen.

Adult↗

PubMed1996

COMT inhibition by entacapone does not affect growth hormone or prolactin secretion in healthy volunteers.

We studied the effects of entacapone, a novel inhibitor of the enzyme catechol-O-methyltransferase (COMT), on spontaneous and levodopa (LD) modulated secretion of growth hormone (GH) and prolactin (PRL) in 12 healthy male volunteers. The study had a double-blind, cross-over design with two experimental settings. In the first setting the subjects received a single oral dose of 400 mg of entacapone or matching placebo in a randomized order. In the second setting, a single oral dose of 300 mg of LD and 75 mg of carbidopa was administered concomitantly with either 400 mg of entacapone or matching placebo in a randomized order. Entacapone had no effect on resting levels of GH, but PRL concentrations in plasma were slightly lower after entacapone than after placebo. As expected, LD/carbidopa increased the concentration of GH and decreased that of PRL. The effects of LD were not influenced by concomitant administration of entacapone. Compared with the administration of LD/carbidopa together with placebo, concomitant administration of entacapone increased the AUC of LD by 29% and reduced the AUC of 3-O-methyldopa (a metabolite of LD produced by COMT) by 69%. Entacapone appears not to enhance the effects of LD on hypothalamic-pituitary function, although the LD dose used may have been bigger than optimal for detection of a small modulatory influence.

Adult↗

PubMed1996

Biofeedback therapy in rectal prolapse patients.

PURPOSE: The aim of the study was to evaluate the effect of perioperative biofeedback training on postoperative continence in patients with rectal prolapse. METHODS: Thirty-six consecutive patients were operated on between 1987 and 1993. Twenty-nine could be traced for reexamination. Four were excluded because of a recurring prolapse. Anal manometry, assessment of rectoanal sensation, and surface electromyography were performed during the reexamination. From 1987 to 1991, no perioperative biofeedback training was given (Group 1, n = 14). Since the beginning of 1992, incontinent patients were given biofeedback training (Group 2, n = 11). RESULTS: Continence scores improved in both study groups. Both study groups had equally low resting pressures compared with Group 3 (controls) (30.6 +/- 14.9 vs. 53.0 +/- 11.9 mmHg; P < 0.001). Anal resting pressure correlated with postoperative continence score, whereas contractile pressures did not (r = -0.5,P < 0.05, and r = -0.3, p = not significant, respectively). CONCLUSION: Biofeedback therapy can improve the function of external sphincter; however, the most important reason for postoperative incontinence in rectal prolapse patients is low resting pressure that cannot be corrected by biofeedback therapy.

Aged↗

PubMed1995

Pharmacokinetics of levosimendan in healthy volunteers and patients with congestive heart failure.

Levosimendan is a new inodilatory agent that sensitizes troponin-C in heart muscle cells to calcium, thus improving contractility. The pharmacokinetics of levosimendan were evaluated using a double-isotope technique in eight healthy volunteers and in eight patients with mild congestive heart failure (CHF). A single i.v. dose of 0.50 mg 14C-labeled levosimendan and a single oral dose of 0.50 mg 13C15N-labeled levosimendan were administered concomitantly. The elimination half-lives (mean +/- SD) of levosimendan were 0.96 +/- 0.16 h in healthy volunteers and 1.03 +/- 0.11 h in patients. The respective figures for total drug were 5.73 +/- 1.53 h and 5.23 +/- 0.99 h. Clearances of levosimendan averaged 359 +/- 69 ml/min in healthy volunteers and 296 +/- 61 ml/min in patients and of total drug 104 +/- 15 and 85 +/- 20 ml/min, respectively. Volumes of distribution at steady state were for levosimendan 21.9 +/- 5.9 L in healthy volunteers and 19.5 +/- 4.5 L in patients and for 14C-drug 27.9 +/- 5.3 L and 23.8 +/- 2.8 L, respectively. The bioavailability of oral levosimendan was 85 +/- 6% in healthy volunteers and 84 +/- 4% in patients.

Administration, Oral↗

PubMed1994

Pharmacokinetics and pharmacodynamics of simendan, a novel calcium sensitizer, in healthy volunteers.

OBJECTIVE: To assess pharmacokinetics and correlation of pharmacokinetics and pharmacodynamics of simendan, a new calcium-sensitizing compound aimed at the treatment of congestive heart failure, in healthy volunteers. METHODS: Simendan was administered to eight healthy subjects in seven different doses, and its concentrations in plasma and proportions of enantiomers (levosimendan and dextrosimendan) were determined. Hemodynamic effects were measured by M-mode echocardiography. RESULTS: The area under the plasma concentration time-curve increased linearly and correlated with dose (p < 0.001). The volumes of distribution were small (mean VC, 8.5 to 14.1 L; VSS, 12.8 to 28.4 L) and elimination fairly fast (mean t1/2 beta, 0.83 to 1.77 hours). There were only minor differences between the pharmacokinetic profiles of the enantiomers of simendan. The increase in maximal ejection fraction (EF) correlated significantly with the plasma concentrations of simendan (p < 0.01; r2 = 0.33). However, the correlation coefficient was higher between estimated concentrations of simendan in peripheral compartment and ejection fraction; r2 was 0.79 (p < 0.01) and 0.94 (p < 0.001) after 2 and 5 mg doses, respectively. One subject after 5 mg simendan and one subject after 10 mg simendan had transient vasovagal reactions consisting of decreases in heart rate and blood pressure. CONCLUSIONS: Simendan has favorable and predictable hemodynamic actions. The pharmacokinetic profile facilitates rapid dose adjustments during intravenous administration.

Adult↗

PubMedDate not supplied

Pharmacokinetics of entacapone, a peripherally acting catechol-O-methyltransferase inhibitor, in man. A study using a stable isotope techique.

OBJECTIVE: This study investigated the pharmacokinetics of the catechol-O-methyltransferase (COMT) inhibitor entacapone by giving simultaneously stable non-radioactive isotope 13C-entacapone intravenously (i.v.) and unlabelled entacapone orally. In comparison with a crossover design, the simultaneous i.v. and oral administration made it possible to minimise intra-individual variation, sample size and the duration of the study and still obtain accurate pharmacokinetic data. METHODS: Eight healthy male volunteers were enrolled in this study. They were given a 20-mg i.v. dose of 13C-entacapone as a 1-mg/ml infusion at a constant rate of 5 mg/min over 4 min and a 100-mg dose of unlabelled entacapone orally immediately after the infusion. Blood samples were drawn at -5 (before onset of infusion), 0 (upon termination of infusion), 2, 5, 10, 20, 30 and 45 min and 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 10 and 12 h after the tablet ingestion. Urine during the 48 h after dosing was collected in fractions. Concentrations of 13C-entacapone and entacapone in plasma samples and urine fractions were determined using gas chromatography-mass spectrometry. RESULTS: The decay of i.v. 13C-entacapone in plasma was tri-exponential and its pharmacokinetics were described using an open three-compartment model. The volume of the central compartment (Vc) and the volume of distribution at steady state (Vss) were 0.08+/-0.03 l/kg and 0.27+/-0.10 l/kg, respectively. Total plasma clearance (Cltot) averaged 11.7+/-1.9 ml/min kg(-1). The half-lives for the distribution phase and for the rapid and terminal elimination phases (t1/2alpha, t1/2beta and t1/2gamma) were 0.05+/-0.01 h, 0.38+/-0.16 h and 2.40+/-1.70 h, respectively. The terminal elimination phase accounted for only 9% of the total area under the plasma concentration-time curve (AUC), which was 409 +/- 98 ng h/ml after the i.v. dose. Oral entacapone was absorbed rapidly with a time to reach the peak concentration (tmax) of 0.9+/-0.4 h, a maximum concentration (Cmax) of 457+/-334 ng/ml and an AUC of 497+/-118 ng h/ml. During the 48 h after dosing, the recovery of free and conjugated unchanged 13C-entacapone in urine was 38.1+/-7.2% of the i.v. dose and the recovery of free and conjugated unchanged entacapone 13.3+/-3.9% of the oral dose. The bioavailability of oral entacapone was 25% based on the AUC values and 35% based on urinary excretion. CONCLUSION: The results of the present study using stable isotope technique indicate that entacapone is rapidly absorbed, distributed to a small volume and rapidly eliminated by mainly non-renal routes. The pharmacokinetic profile of entacapone provides the rationale for a concomitant and frequently repeated simultaneous dosing of entacapone with levodopa and dopa decarboxylase inhibitors in the treatment of Parkinson's disease. This study confirmed the previously published data and fully support the validity of the technique used.

Administration, Oral↗