Elimination of pindolol in liver disease

Evaluation of Information in Summaries of Product Characteristics (SmPCs) on the Use of a Medicine in Patients With Hepatic Impairment

Background: In 2005, the European Medicines Agency (EMA) released guidance on pharmacokinetic studies in patients with hepatic impairment. This guidance describes the design of these studies and what information should be presented in the Summary of Product Characteristics (SmPC). We aim to evaluate the availability and clinical applicability of information on medicine use in patients with hepatic impairment in SmPCs and registrational dossiers of recently approved medicines. Methods: We reviewed SmPC information on use in patients with hepatic impairment of 51 new medicines authorized between 2015 and 2017. Per medicine, we assessed the availability of nine information items derived from the EMA guidance, i.e. type of hepatic disease studied; stratification by severity of hepatic impairment; influence of hepatic impairment on the pharmacokinetics; safety advice in mild, moderate, and severe hepatic impairments; and dosing recommendation in mild, moderate, and severe hepatic impairments. If unavailable, the European Public Assessment Report (EPAR) and study report were consulted consecutively. Of available items, clinical applicability was assessed by labeling information as "clear" or "ambiguous". Results: Of 51 medicines, 15 had no pharmacokinetic study in patients with hepatic impairment described in their SmPC. The other 36 SmPCs contained on average seven of the nine information items (range 4-9). One SmPC contained all 9 items, and after consulting, the study reports, 11 SmPCs were complete. The item "type of hepatic disease studied" was available in one SmPC, though it could be retrieved in 21 study reports. Regarding clinical applicability, there was no medicine with all information items available and clearly formulated in the SmPC. A total of 12 medicines (33%) contained only clearly formulated information, while 24 (67%) contained at least one ambiguously formulated information item (range 0-4). Items often ambiguously formulated were: "definition of mild, moderate, and severe hepatic impairment" (15 ambiguous SmPCs) and "safety advice in severe hepatic impairment" (17 ambiguous SmPCs). Conclusion: While SmPCs contain a large part of information requested by the EMA, clinical applicability seems low, as it is often unclear to which specific type of hepatic disease patient the advice applies. This can negatively influence the practical use by healthcare professionals.

Enantioselectivity in the steady-state pharmacokinetics and transplacental distribution of pindolol at delivery in pregnancy-induced hypertension

Nine patients taking oral doses of 10 mg/12 h rac-pindolol as part of their treatment for hypertension in pregnancy were recruited for the study. Maternal and fetal gestational age ranged from 20-38 years and 28-41 weeks, respectively. Blood was collected from the umbilical cord vein and from the mother from zero to 12 h after drug administration. Urine was collected for 12 h after rac-pindolol administration at the following intervals: 0-3, 3-6, 6-9, and 9-12 h. Plasma and urine concentrations of the pindolol enantiomers were determined by HPLC using a Chiralpak AD chiral column and fluorescence detection. The data were fitted to a one-compartment model and differences between (+)-R and (-)-S enantiomers were compared by the paired t-test (P < 0.05). Mean results are reported. The disposition of pindolol in maternal plasma was stereoselective, with higher AUC(SS)0-12 (84.34 vs. 95.69 ng.h/ml) and Cl(R) values (9.16 vs. 10.85 L/h) and lower Vd/f (251.38 vs. 225.17 L) and Cl/f (62.48 vs. 55.74 L/h) for the (+)-R pindolol. The transplacental distribution of pindolol was not stereoselective. Cord, plasma, and presumably fetal, concentrations of the pindolol enantiomers were 56% of the maternal plasma concentrations up to 6 h after the last dose.

Effectiveness of pindolol with selected antidepressant drugs in the treatment of major depression

On the basis of a previous report suggesting the effectiveness of the beta-adrenoceptor/5-HT1A antagonist pindolol to accelerate the antidepressant effect of a selective serotonin reuptake inhibitor (SSRI) and to produce a therapeutic effect in drug-resistant depressed patients, these open studies were undertaken to further explore the safety and efficacy of this strategy. In a first study, nine untreated unipolar depressed patients were given the SSRI paroxetine (20 mg/day) together with pindolol (2.5 mg thrice daily). One patient stopped taking pindolol because of increased irritability after 3 days. One week later, seven patients had their Hamilton Rating Scale for Depression Score decreased by more than 50%. In a second study, 19 drug-resistant unipolar depressed patients (9 on paroxetine, 5 on sertraline, 3 on fluoxetine, and 2 on moclobemide) were also given pindolol at the same regimen and were assessed weekly. Two patients (one on sertraline, one on moclobemide) stopped taking pindolol also because of increased irritability after 2 and 3 days, respectively. After 1 week of pindolol addition, 10 patients had a more than 50% decrease of their depression score. By day 14, all of the patients had a score of 10 or less, with the exception of those on sertraline. Improvement was maintained in all patients for at least 28 days on this combination. The results of these studies indicate that pindolol is safe when used in combination with an SSRI or moclobemide. Given the positive results obtained in this second open trial in 28 patients, this treatment strategy should be tested under double-blind conditions to establish its efficacy.

Pharmacokinetics of encainide in patients with cirrhosis

The pharmacokinetics of encainide were investigated in 10 patients with cirrhosis and 10 matched controls following single intravenous (IV, 25 mg), single oral (so, 25 mg), and multiple oral (mo, 25 mg thrice daily over 5 days) dosing. The hepatic oxidative drug-metabolizing enzyme capacity and its inducibility were assessed by antipyrine elimination and 6-beta-hydroxycortisol excretion. Eight controls and nine patients were of the extensive metabolizer phenotype (EM), as assessed by the sparteine metabolic ratio. Statistics was performed in EM only. The antipyrine half-life was significantly longer and clearance was significantly lower in patients with cirrhosis. Following IV administration, no significant differences in encainide half-life clearance, volume of distribution, or the area under the plasma concentration time curve (AUC) were observed between patients and controls. Following so and mo, there was a fourfold reduction in the oral clearance in cirrhotics. Thus, encainide bioavailability was increased in cirrhosis. Whereas the AUC of encainide was significantly higher in patients, no differences were observed in its active metabolites, O-desmethyl-encainide (ODE) and 3-methoxy-O-desmethylencainide (MODE). Plasma concentrations of encainide and its metabolites after 3 and 5 days of mo suggested steady-state conditions after 3 days of oral dosing. No change in antipyrine elimination and 6-beta-hydroxycortisol excretion following mo occurred. There was no relationship between parameters of encainide and antipyrine elimination. In conclusion, even though the elimination of encainide was reduced in patients with cirrhosis, plasma levels of the pharmacologically active metabolites, ODE and MODE, were comparable.(ABSTRACT TRUNCATED AT 250 WORDS)

The pharmacokinetics of lignocaine and beta-adrenoceptor antagonists in patients with acute myocardial infarction

Lignocaine (lidocaine) and beta-adrenoceptor antagonists are widely used after acute myocardial infarction. The therapeutic value of these agents depends on the achievement and maintenance of safe and effective plasma concentrations. Lignocaine pharmacokinetics after acute myocardial infarction (MI) are controlled by a number of variables. The single most important is left ventricular function, which affects both volume of distribution and plasma clearance. Other major factors include bodyweight, age, hepatic function, the presence of obesity, and concomitant drug therapy. Lignocaine is extensively bound to alpha 1-acid glycoprotein, a plasma protein which is also an acute phase reactant. Increases in alpha 1-acid glycoprotein concentration occur after an acute MI, decreasing the free fraction of lignocaine in the plasma and consequently decreasing total plasma lignocaine clearance without altering the clearance of non-protein-bound lignocaine. Complex changes in lignocaine disposition occur with long term infusions, and therefore early discontinuation of lignocaine infusions (within 24 hours) should be undertaken whenever possible. Because the risk of ventricular tachyarrhythmia declines rapidly after the onset of an acute MI, lignocaine therapy can be rationally discontinued within 24 hours in most patients. Lignocaine has a narrow toxic/therapeutic index, so that pharmacokinetic factors are critical in dose selection. In contrast, beta-adrenoceptor antagonists' adverse effects are more related to the presence of predisposing conditions (such as asthma, heart failure, bradyarrhythmias, etc.) than to plasma concentration. The pharmacokinetics of beta-adrenoceptor antagonists are important to help assure therapeutic efficacy, to provide information about the anticipated time course of drug action, and to predict the possible role of ancillary drug effects (such as direct membrane action) and loss of cardioselectivity. Lipid solubility is the main determinant of the pharmacokinetic properties of a beta-adrenoceptor antagonist. Lipid-soluble agents like propranolol and metoprolol are well absorbed orally, and undergo rapid hepatic metabolism, with important presystemic clearance and a short plasma half-life. Water-soluble drugs like sotalol, atenolol, and nadolol are less well absorbed, and are eliminated more slowly by renal excretion. Clinical assessment of beta-adrenoceptor antagonism is more valuable than plasma concentration determinations in evaluating the adequacy of the dose of a particular beta-adrenoceptor antagonist.(ABSTRACT TRUNCATED AT 400 WORDS)

Bioavailability and elimination of nitrendipine in liver disease

Twenty one patients with liver disease (cirrhosis 11, chronic hepatitis 5 and acute hepatitis 5) and 6 healthy volunteers were given a single i.v. dose of nitrendipine 5 mg. Afterwards nitrendipine 20 mg once daily were administered orally for seven days. With the intravenous injection a significant increase in the AUC and elimination half-life of nitrendipine was found in patients with cirrhosis as compared to the normal volunteers. After chronic oral dosing, the area under the plasma concentration-time curve, AUC (0-24), was 94.5 ng ml-1 h and the plasma clearance CL was 1380.6 ml/min in the healthy controls; in patients with cirrhosis the AUC (0-24) h was significantly greater at 309.4 ng ml-1 h and CL had fallen to 686.6 ml/min. Considerable accumulation of nitrendipine was also found in the patients with chronic hepatitis. Nitrendipine could not be detected in urine from any of the subjects. Blood pressure and heart rate were not significantly influenced by the treatment in the various groups investigated. Antipyrine clearance in the patients with cirrhosis was correlated with the nitrendipine plasma clearance. Thus, accumulation of nitrendipine has been demonstrated in the patients with cirrhosis and chronic hepatitis.

Reduction of paracetamol and aspirin metabolism during viral hepatitis

The single-dose pharmacokinetics of two analgesic drugs, paracetamol (acetaminophen) and aspirin, were studied in healthy volunteers and in patients with viral hepatitis during the acute and the convalescent phase. Impaired elimination of paracetamol and aspirin was found in hepatitis patients, while plasma peak concentrations were unaffected. Recovered patients were not different from healthy controls in the rate of drug elimination. The data suggest normal single dosage for these drugs in acute viral hepatitis, and dosage modification only in severe cases.

Bioavailability and elimination of digitoxin in patients with hepatorenal insufficiency

Following administration of digitoxin, 1 mg intravenously, the pharmacokinetics of this glycoside were studied in eight healthy volunteers and in eight patients with hepatorenal insufficiency (mean creatinine clearance 19.6 +/- 2.9 ml/min; antipyrine clearance 25.6 +/- 3.2 ml/min; means +/- SEM). Liver cirrhosis of the patients was confirmed by liver biopsy. Plasma protein binding of digitoxin (means +/- SEM) was 95.1 +/- 0.7% in the patients and 95.6 +/- 1.2% in the volunteers (NS). Total body clearance of digitoxin was 0.0530 +/- 0.0040 ml/min/kg of body weight in the patients and 0.0547 +/- 0.0043 ml/min/kg of body weight in the healthy subjects (NS). When elimination half-lives of the patients and the volunteers were compared, there was also no significant difference (7.0 +/- 0.77 days in the patient group and 7.8 +/- 0.8 days in the volunteers). Our data concerning digitoxin kinetics in patients with hepatorenal insufficiency do not indicate an accumulation of the drug in these patients.

Stereoselective renal clearance of pindolol in humans

In this study, pindolol, a beta-adrenoceptor blocking agent marketed as a racemic mixture, was used as a model compound to investigate stereoselective renal clearance of organic cations in human beings. Six normal subjects received an oral dose of 20 mg racemic pindolol. Heart rate and blood pressure were measured throughout the study. A stereospecific high performance liquid chromatographic procedure was used to quantitate the concentrations of d- and l-pindolol in plasma and urine. Renal clearance and other pharmacokinetic parameters of both enantiomers were calculated and compared. The renal clearance of l-pindolol was greater than that of d-pindolol in all subjects. The renal clearance (mean +/- SD) was 240 +/- 55 ml/min for l-pindolol and 200 +/- 51 ml/min for d-pindolol (P less than 0.01). Since stereoselective binding to plasma proteins was not observed, differences in renal clearance between d- and l-pindolol were caused by either stereoselective renal transport, or stereoselective renal metabolism. The area under the plasma concentration-time curve, the amount of drug excreted, and the half-life of l-pindolol were greater than those of d-pindolol, which suggests that pindolol was also eliminated stereoselectively by nonrenal routes. The slopes of the resting heart rate vs. the plasma concentration of l-pindolol were significantly less than zero and were significantly correlated to the pretreatment heart rate, which supports the hypothesis that intrinsic sympathetic tone largely determines the effect of pindolol on the resting heart rate. The observation that pindolol is eliminated stereoselectively by the kidney may have clinical implications for other racemic drugs that are renally eliminated.

The effect of liver cirrhosis on the pharmacokinetics of phenprocoumon

Phenprocoumon was given orally to 9 patients with biopsy proven liver cirrhosis (dose range 0.12-0.25 mg/kg) and to 7 healthy volunteers (0.23 mg/kg). Concentrations of phenprocoumon were determined using HPLC in plasma and urine samples obtained for 6-7 days after drug administration. The binding of [3H]-phenprocoumon in plasma from all subjects was determined by equilibrium dialysis. Antipyrine plasma concentrations were determined spectrophotometrically following oral administration of antipyrine (1200 mg). The total body clearance of phenprocoumon was higher in the cirrhotic patients (1.64 +/- 0.16 ml/h/kg mean +/- SEM) than in the healthy volunteers (0.90 +/- 0.07 ml/h/kg), however the free drug clearance was not significantly different in the patients (144 +/- 14 ml/h/kg) compared with normal (113 +/- 11 ml/h/kg). In contrast the clearance of antipyrine was much reduced in the cirrhotic group (17.5 +/- 2.9 ml/h/kg) compared with normal (35.6 +/- 3.9 ml/h/kg). The metabolic clearance of phenprocoumon via glucuronidation, is relatively unaffected during cirrhosis compared with antipyrine clearance via oxidation.