Propranolol stereoisomer plasma concentrations and portal haemodynamic response in patients with liver cirrhosis

Neuroimmunomodulation of adrenoblockers during liver cirrhosis: modulation of hepatic stellate cell activity

The sympathetic nervous system and the immune system are responsible for producing neurotransmitters and cytokines that interact by binding to receptors; due to this, there is communication between these systems. Liver immune cells and nerve fibres are systematically distributed in the liver, and the partial overlap of both patterns may favour interactions between certain elements. Dendritic cells are attached to fibroblasts, and nerve fibres are connected via the dendritic cell-fibroblast complex. Receptors for most neuroactive substances, such as catecholamines, have been discovered on dendritic cells. The sympathetic nervous system regulates hepatic fibrosis through sympathetic fibres and adrenaline from the adrenal glands through the blood. When there is liver damage, the sympathetic nervous system is activated locally and systemically through proinflammatory cytokines that induce the production of epinephrine and norepinephrine. These neurotransmitters bind to cells through α-adrenergic receptors, triggering a cellular response that secretes inflammatory factors that stimulate and activate hepatic stellate cells. Hepatic stellate cells are key in the fibrotic process. They initiate the overproduction of extracellular matrix components in an active state that progresses from fibrosis to liver cirrhosis. It has also been shown that they can be directly activated by norepinephrine. Alpha and beta adrenoblockers, such as carvedilol, prazosin, and doxazosin, have recently been used to reverse CCl₄-induced liver cirrhosis in rodent and murine models.KEY MESSAGESNeurotransmitters from the sympathetic nervous system activate and increase the proliferation of hepatic stellate cells.Hepatic fibrosis and cirrhosis treatment might depend on neurotransmitter and hepatic nervous system regulation.Strategies to reduce hepatic stellate cell activation and fibrosis are based on experimentation with α-adrenoblockers.

Beta-blockers in patients with liver cirrhosis: Pragmatism or perfection?

With increasing decompensation, hyperdynamic circulatory disturbance occurs in liver cirrhosis despite activation of vasoconstrictors. Here, the concept of a therapy with non-selective beta-blockers was established decades ago. They lower elevated portal pressure, protect against variceal hemorrhage, and may also have pleiotropic immunomodulatory effects. Recently, the beneficial effect of carvedilol, which blocks alpha and beta receptors, has been highlighted. Carvedilol leads to "biased-signaling" via recruitment of beta-arrestin. This effect and its consequences have not been sufficiently investigated in patients with liver cirrhosis. Also, a number of questions remain open regarding the expression of beta-receptors and its intracellular signaling and the respective consequences in the intra- and extrahepatic tissue compartments. Despite the undisputed role of non-selective beta-blockers in the treatment of liver cirrhosis, we still can improve the knowledge as to when and how beta-blockers should be used in which patients.

Clinical Pharmacokinetics of Propranolol Hydrochloride: A Review

BACKGROUND

Nobel laureate Sir James Black's molecule, propranolol, still has broad potential in cardiovascular diseases, infantile haemangiomas and anxiety. A comprehensive and systematic review of the literature for the summarization of pharmacokinetic parameters would be effective to explore the new safe uses of propranolol in different scenarios, without exposing humans and using virtual-human modeling approaches.

OBJECTIVE

This review encompasses physicochemical properties, pharmacokinetics and drug-drug interaction data of propranolol collected from various studies.

METHODS

Clinical pharmacokinetic studies on propranolol were screened using Medline and Google Scholar databases. Eighty-three clinical trials, in which pharmacokinetic profiles and plasma time concentration were available after oral or IV administration, were included in the review.

RESULTS

The study depicts that propranolol is well absorbed after oral administration. It has dose-dependent bioavailability, and a 2-fold increase in dose results in a 2.5-fold increase in the area under the curve, a 1.3-fold increase in the time to reach maximum plasma concentration and finally, 2.2 and 1.8-fold increase in maximum plasma concentration in both immediate and long-acting formulations, respectively. Propranolol is a substrate of CYP2D6, CYP1A2 and CYP2C19, retaining potential pharmacokinetic interactions with co-administered drugs. Age, gender, race and ethnicity do not alter its pharmacokinetics. However, in renal and hepatic impairment, it needs a dose adjustment.

CONCLUSION

Physiochemical and pooled pharmacokinetic parameters of propranolol are beneficial to establish physiologically based pharmacokinetic modeling among the diseased population.

Comprehensive plasma-screening for known and unknown substances in doping controls

Occasionally, doping analysis has been recognized as a competitive challenge between cheating sportsmen and the analytical capabilities of testing laboratories. Both have made immense progress during the last decades, but obviously the athletes have the questionable benefit of frequently being able to switch to new, unknown and untested compounds to enhance their performance. Thus, as analytical counteraction and for effective drug testing, a complementary approach to classical targeted methods is required in order to implement a comprehensive screening procedure for known and unknown xenobiotics. The present study provides a new analytical strategy to circumvent the targeted character of classical doping controls without losing the required sensitivity and specificity. Using 50 microL of plasma only, the method potentially identifies illicit drugs in low ng/mL concentrations. Plasma provides the biological fluid with the circulating, unmodified xenobiotics; thus the identification of unknown compounds is facilitated. After a simple protein precipitation, liquid chromatographic separation and subsequent detection by means of high resolution/high accuracy orbitrap mass spectrometry, the procedure enables the determination of numerous compounds from different classes prohibited by the World Anti-Doping Agency (WADA). A new hyphenated mass spectrometry technology was employed without precursor ion selection for higher collision energy dissociation (HCD) fragmentation experiments. Thus the mass spectra contained all the desired information to identify unknown substances retrospectively. The method was validated for 32 selected model compounds for qualitative purposes considering the parameters specificity, selectivity, limit of detection (<0.1-10 ng/mL), precision (9-28%), robustness, linearity, ion suppression and recovery (80-112%). In addition to the identification of unknown compounds, the plasma samples were simultaneously screened for known prohibited targets.

H3 Propranolol serum levels following lidocaine administration in rats with CCL4 — induced liver damage

Liver disease alters the pharmacokinetic and pharmacodynamic properties of hepatically eliminated drugs. The main factors influenced are plasma albumin levels, enzyme balance (induction & inhibition) and drug binding to tissue proteins. The influence of lidocaine on serum, heart and liver propranolol levels in Wistar rats after liver injury induced by carbon tetrachloride CCl4 0.4 ml/kg x 2/wkl, was investigated. 40 male Wistar rats were divided into four groups (I, II, III, IV; n=10), Group I animals received only propranolol (labelled + cold substance) 40 mg/kg/12 h p.o., group II propranolol plus lidocaine in a single dose of 4mg/kg s.c., group III was treated with CCl4 for 6 weeks and received propranolol x2 at the same dosage as group I, while group VI was treated with CCl4 and the same drug dosage as group II. The simultaneous administration of H3-propranolol and lidocaine increased propranolol levels in the serum and tissues. The liver in damaged animals showed an increase of propranolol level under lidocaine co-administration, probably due to CCl4 induced liver enzyme activity, resulting in a rapid propranolol metabolism or to competition between both drug protein binding sites. The increased propranolol levels in the heart after lidocaine administration were probably due to attributed to its high affinity for heart tissue. Consequently, as regards the therapeutic approach for patients with liver disease receiving propranolol their propranolol dosage should be reduced when lidocaine is co-administered.

Acute hemodynamic effects of octreotide and terlipressin in patients with cirrhosis: a randomized comparison

BACKGROUND

Octreotide and terlipressin are widely used in acute variceal hemorrhage to reduce the bleeding rate. They purportedly act by mesenteric arterial vasoconstriction, thus reducing portal venous flow (PVF) and portal pressure. Little is known about the immediate-early hemodynamic effects of these drugs.

AIM

To compare the acute hemodynamic effects of octreotide and terlipressin in patients with cirrhosis.

PATIENTS

Forty-two cirrhotic patients with a history of variceal bleeding were randomized to receive either octreotide 100 microg intravenous bolus followed by a continuous infusion at 250 microg/h (n = 21), or terlipressin 2 mg intravenous bolus (n = 21).

METHODS

Mean arterial pressure (MAP), heart rate (HR), hepatic venous pressure gradient (HVPG), and PVF, assessed by duplex Doppler ultrasonography, were measured before and at 1, 5, 10, 15, 20, and 25 min after the start of drug administration.

RESULTS

Octreotide markedly decreased HVPG (-44.5 +/- 17.8%) and PVF (-30.6 +/- 13.6%) compared to the baseline at 1 min (p < 0.05). Thereafter, both variables rapidly returned toward the baseline, and by 5 min, no significant differences in HVPG (-7.1 +/- 28.9%) and PVF (10.2 +/- 26.2%) were noted. A similar transient effect on MAP and HR was observed. Terlipressin significantly decreased HVPG (-18.3 +/- 11.9%) and PVF (-32.6 +/- 10.5%) at 1 min (p < 0.05) and sustained these effects at all time points. The effects on arterial pressure and HR were also sustained.

CONCLUSIONS

Octreotide only transiently reduced portal pressure and flow, whereas the effects of terlipressin were sustained. These results suggest that terlipressin may have more sustained hemodynamic effects in patients with bleeding varices.

Relationship of hemodynamic indices and prognosis in patients with liver cirrhosis

BACKGROUND

Hyperdynamic circulation due to reduced peripheral vascular resistance and increased cardiac output, and the development of portal hypertension are the hemodynamic changes observed in patients with liver cirrhosis. Such hemodynamic abnormalities appear in patients with late stage liver cirrhosis. Therefore, hemodynamic indices, which represent hyperdynamic circulation and portal hypertension, are significant for the prognosis of patients with liver cirrhosis. The aim of this study was to determine the hemodynamic indices associated with the prognosis of patients with liver cirrhosis.

METHODS

A total of 103 patients diagnosed with liver cirrhosis between December 1999 and June 2003, with a mean follow-up period of 73 weeks, ranging from 7 to 168 weeks, were recruited. Using Child-Pugh classification, the mean arterial pressure, heart rate and hepatic venous pressure gradient (HVPG) were measured. The indices of Doppler ultrasonography, including the portal and splenic venous flows, and the resistance of the hepatic, splenic, and renal arteries were also measured using the arterial pulsatility index (PI). The prognostic values of these indices were determined by their comparison with the patient survivals.

RESULTS

Significant hemodynamic indices for a bad prognosis were high HVPG (> or = 15 mmHg) and renal arterial PI (> or = 1.14)(p<0.05). A Child-Pugh score > or = 10 was important for a poor prognosis (p<0.05).

CONCLUSION

Severe portal hypertension (HVPG > or = 15 mmHg) and high renal arterial resistance (PI +/- 1.14) were valuable hemodynamic indices for the prognosis of patients with liver cirrhosis. Therefore, it was concluded that the measurement of these hemodynamic indices, in addition to the Child-Pugh classification, is helpful in the prognosis of patients with liver cirrhosis.

Hemodynamic effects of the angiotensin II receptor antagonist irbesartan in patients with cirrhosis and portal hypertension

BACKGROUND & AIMS

Angiotensin II receptor antagonists have been proposed as new drugs for portal hypertension. This randomized, placebo-controlled, double-blind study aimed to assess the effect of the angiotensin II receptor antagonist irbesartan on portal and systemic hemodynamics and renal function in patients with cirrhosis.

METHODS

Thirty-six patients with cirrhosis and portal hypertension received 150 mg/d irbesartan or placebo for 1 week. Systemic hemodynamics, kidney and liver function parameters were recorded regularly; hepatic venous pressure gradient and plasma renin were assessed on days 0 and 7.

RESULTS

Irbesartan reduced the hepatic venous pressure gradient by 12.2% +/- 6.6% (P < 0.05) and mean arterial pressure by 5.3% +/- 4.0% in 13 of 18 verum patients. In 4 (22%) verum patients, arterial hypotension, accompanied by significant renal impairment, required withdrawal of irbesartan. In these patients, baseline plasma renin (P < 0.002) and cystatin C (P < 0.001) levels were higher, and creatinine clearance (P < 0.02), serum sodium (P < 0.01), and albumin (P < 0.05) were lower than in patients who tolerated irbesartan. Four of five patients with baseline renin >900 microU/mL developed treatment-limiting hypotension.

CONCLUSIONS

The angiotensin II receptor antagonist irbesartan is not advisable in patients with advanced cirrhosis and high plasma renin because it may induce arterial hypotension and only moderately reduces portal pressure.

Review article: a drug therapy for the prevention of variceal haemorrhage

The development of varices is a major complication of cirrhosis, and variceal haemorrhage has a high mortality. There have been major advances in the primary and secondary prevention of variceal haemorrhage over the last 20 years involving endoscopic, radiological and pharmacological approaches. This review concentrates principally on drug therapy, particularly on the numerous haemodynamic studies. Many of these drugs have not been studied in clinical trials, but provide data about the underlying pathogenesis of portal hypertension. Also covered in this review are the randomized controlled trials and meta-analyses that involve a large number of patients. These trials involve relatively few drugs such as non-selective beta-blockers and nitrates. Correlations between haemodynamic and clinical parameters are discussed. Despite the recent increase in the use of alternative endoscopic therapies, an effective and well tolerated drug remains a clinically important research goal.

Comparison of portal vein velocity and the hepatic venous pressure gradient in assessing the acute portal hemodynamic response to propranolol in patients with cirrhosis

OBJECTIVE

The aim of this prospective study was to compare noninvasive Doppler sonography and invasive measurement of the hepatic venous pressure gradient (HVPG) to determine the acute portal hemodynamic response to propranolol in patients with liver cirrhosis.

METHODS

In a blinded study design, portal vein velocity (PVV) and HVPG were simultaneously assessed in 11 cirrhotic patients for 4 h after oral ingestion of 40 mg propranolol.

RESULTS

Both HVPG (17.2% +/- 4.3%, p < 0.0001) and PVV (15.6% +/- 2.1%, p < 0.0002) showed a highly significant reduction during the study period versus baseline. Based on HVPG measurements, four patients (36%) were classified as nonresponders. These patients had a significantly lower PVV reduction compared to the responders (responders: 18.8% +/- 2.0% vs nonresponders: 10.0% +/- 2.1%, p < 0.05). Nonresponders were identified by Doppler sonography with a sensitivity of 1.0, specificity of 0.86, and positive predictive value of 0.9 when a threshold of 20% PVV reduction 120 min after drug intake was applied.

CONCLUSIONS

Doppler sonography is a useful tool for assessment of the acute portal hemodynamic effect of propranolol. To distinguish portal hemodynamic nonresponders from responders to propranolol, PVV measurements should be carried out 2 h after drug administration, and PVV reduction should be not <20% in propranolol responders.