Association of the G-protein and α2-adrenergic receptor gene and plasma norepinephrine level with clonidine improvement of the effects of diuretics in patients with cirrhosis with refractory ascites: a randomised clinical trial

Effect of alpha agonists on the prevention of postparacentesis circulatory dysfunction in patients with refractory or recurrent ascites: a meta-analysis

Postparacentesis circulatory dysfunction (PCD) is one of the commonest complications encountered in patients with refractory or recurrent ascites. Alpha agonists like clonidine and midodrine have been studied in various clinical trials for the prevention of PCD with varied results. This meta-analysis was done to evaluate the effect of alpha agonists on prevention of PCD in patients of refractory or recurrent ascites. A standard meta-analysis protocol was developed and registered in the International Prospective register of Ongoing Systematic Reviews. After performing a comprehensive literature search in MEDLINE, Cochrane, and International Clinical Trial Registry Platform, reviewers assessed eligibility and extracted data from five relevant articles. Preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines were followed in selection, analysis, and reporting of findings. Random effects model was used to estimate effect size. Quality assessment was done using the risk of bias assessment tool and meta-regression for probable variables affecting effect size. The random effect model analysis revealed a mean reduction of 2.63 ng/ml/h (95% CI: -4.46 to -0.8; P = 0.005) in plasma renin activity (PRA), mean reduction of 255.37 pg/ml (95% CI: -441.23 to -69.5; P = 0.007) in plasma aldosterone levels, and a mean increase of 0.14 mg/dl (95% CI: -0.13 to 0.41; P = 0.32) in serum creatinine levels favouring add-on alpha agonist group. In meta-regression, change in PRA (P = 0.79) and plasma aldosterone (P = 0.93) did not show a significant difference due to variation in follow-up duration across various studies. Add-on alpha agonists bring about a significant reduction in PRA and plasma aldosterone compared to standard medical treatment and thus prevents the occurrence of PCD in patients with refractory or recurrent ascites.

Refractory ascites-the contemporary view on pathogenesis and therapy

Refractory ascites (RA) refers to ascites that cannot be mobilized or that has an early recurrence that cannot be prevented by medical therapy. Every year, 5–10% of patients with liver cirrhosis and with an accumulation of fluid in the peritoneal cavity develop RA while undergoing standard treatment (low sodium diet and diuretic dose up to 400 mg/day of spironolactone and 160 mg/day of furosemide). Liver cirrhosis accounts for marked alterations in the splanchnic and systemic hemodynamics, causing hypovolemia and arterial hypotension. The consequent activation of renin-angiotensin and sympathetic systems and increased renal sodium re-absorption occurs during the course of the disease. Cirrhotic patients with RA have poor prognoses and are at risk of developing serious complications. Different treatment options are available, but only liver transplantation may improve the survival of such patients.

Current approaches to the management of patients with cirrhotic ascites

This review describes current approaches to the management of patients with cirrhotic ascites in relation to the severity of its clinical manifestations. The PubMed database, the Google Scholar retrieval system, the Cochrane Database of Systematic Reviews, and the reference lists from related articles were used to search for relevant publications. Articles corresponding to the aim of the review were selected for 1991-2018 using the keywords: “liver cirrhosis,” “portal hypertension,” “ascites,” “pathogenesis,” “diagnostics,” and “treatment.” Uncomplicated and refractory ascites in patients with cirrhosis were the inclusion criteria. The literature analysis has shown that despite the achievements of modern hepatology, the presence of ascites is associated with poor prognosis and high mortality. The key to successful management of patients with ascites may be the stratification of the risk of an adverse outcome and personalized therapy. Pathogenetically based approach to the choice of pharmacotherapy and optimization of minimally invasive methods of treatment may improve the quality of life and increase the survival rate of this category of patients.

Management of refractory cirrhotic ascites: challenges and solutions

Among the various risky complications of liver cirrhosis, refractory ascites is associated with poor survival of cirrhotics and persistently worsens their quality of life (QOL). Major clinical guidelines worldwide define refractory ascites as ascites that cannot be managed by medical therapy either because of a lack of response to maximum doses of diuretics or because patients develop complications related to diuretic therapy that preclude the use of an effective dose of diuretics. Due to the difficulty in receiving a liver transplantation (LT), the ultimate solution for refractory ascites, most cirrhotic patients have selected the palliative therapy such as repeated serial paracentesis, transjugular intrahepatic portosystemic shunt, or peritoneovenous shunt to improve their QOL. During the past several decades, new interventions and methodologies, such as indwelling peritoneal catheter, peritoneal-urinary drainage, and cell-free and concentrated ascites reinfusion therapy, have been introduced. In addition, new medical treatments with vasoconstrictors or vasopressin V2 receptor antagonists have been proposed. Both the benefits and risks of these old and new modalities have been extensively studied in relation to the pathophysiological changes in ascites formation. Although the best solution for refractory ascites is to eliminate hepatic failure either by LT or by causal treatment, the selection of the best palliative therapy for individual patients is of utmost importance, aiming at achieving the longest possible, comfortable life. This review briefly summarizes the changing landscape of variable treatment modalities for cirrhotic patients with refractory ascites, aiming at clarifying their possibilities and limitations. Evolving issues with regard to the impact of gut-derived systemic and local infection on the clinical course of cirrhotic patients have paved the way for the development of a new gut microbiome-based therapeutics. Thus, it should be further investigated whether the early therapeutic approach to gut dysbiosis provides a better solution for the management of cirrhotic ascites.

Interventions for chronic non-hypovolaemic hypotonic hyponatraemia

BACKGROUND

Chronic (present > 48 hours) non-hypovolaemic hyponatraemia occurs frequently, can be caused by various conditions, and is associated with shorter survival and longer hospital stays. Many treatments, such as fluid restriction or vasopressin receptor antagonists can be used to improve the hyponatraemia, but whether that translates into improved patient-important outcomes is less certain.

OBJECTIVES

This review aimed to 1) look at the benefits and harms of interventions for chronic non-hypovolaemic hypotonic hyponatraemia when compared with placebo, no treatment or head-to-head; and 2) determine if benefits and harms vary in absolute or relative terms dependent on the specific compound within a drug class, on the dosage used, or the underlying disorder causing the hyponatraemia.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 1 December 2017 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. We also screened the reference lists of potentially relevant studies, contacted authors, and screened the websites of regulatory agencies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs that compared the effects of any intervention with placebo, no treatment, standard care, or any other intervention in patients with chronic non-hypovolaemic hypotonic hyponatraemia. We also included subgroups with hyponatraemia from studies with broader inclusion criteria (e.g. people with chronic heart failure or people with cirrhosis with or without hyponatraemia), provided we could obtain outcomes for participants with hyponatraemia from the report or the study authors.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. We expressed treatment effects as mean difference (MD) for continuous outcomes (health-related quality of life, length of hospital stay, change from baseline in serum sodium concentration, cognitive function), and risk ratio (RR) for dichotomous outcomes (death, response and rapid increase in serum sodium concentration, hypernatraemia, polyuria, hypotension, acute kidney injury, liver function abnormalities) together with 95% confidence intervals (CI).

MAIN RESULTS

We identified 35 studies, enrolling 3429 participants. Twenty-eight studies (3189 participants) compared a vasopressin receptor antagonist versus placebo, usual care, no treatment, or fluid restriction. In adults with chronic, non-hypovolaemic hypotonic hyponatraemia, vasopressin receptor antagonists have uncertain effects on death at six months (15 studies, 2330 participants: RR 1.11, 95% CI 0.92 to 1.33) due to risk of selective reporting and serious imprecision; and on health-related quality of life because results are at serious risk of performance, selective reporting and attrition bias, and suffer from indirectness related to the validity of the Short Form Health Survey (SF-12) in the setting of hyponatraemia. Vasopressin receptor antagonists may reduce hospital stay (low certainty evidence due to risk of performance bias and imprecision) (3 studies, 610 participants: MD -1.63 days, 95% CI -2.96 to -0.30), and may make little or no difference to cognitive function (low certainty evidence due to indirectness and imprecision). Vasopressin receptor antagonists probably increase the intermediate outcome of serum sodium concentration (21 studies, 2641 participants: MD 4.17 mmol/L, 95% CI 3.18 to 5.16), corresponding to two and a half as many people having a 5 to 6 mmol/L increase in sodium concentration compared with placebo at 4 to 180 days (moderate certainty evidence due to risk of attrition bias) (18 studies, 2014 participants: RR 2.49, 95% CI 1.95 to 3.18). But they probably also increase the risk of rapid serum sodium correction - most commonly defined as > 12 mmol/L/d (moderate certainty evidence due to indirectness) (14 studies, 2058 participants: RR 1.67, 95% CI 1.16 to 2.40) and commonly cause side-effects such as thirst (13 studies, 1666 participants: OR 2.77, 95% CI 1.80 to 4.27) and polyuria (6 studies, 1272 participants): RR 4.69, 95% CI 1.59 to 13.85) (high certainty evidence). The potential for liver toxicity remains uncertain due to large imprecision. Effects were generally consistent across the different agents, suggesting class effect.Data for other interventions such as fluid restriction, urea, mannitol, loop diuretics, corticosteroids, demeclocycline, lithium and phenytoin were largely absent.

AUTHORS' CONCLUSIONS

In people with chronic hyponatraemia, vasopressin receptor antagonists modestly raise serum sodium concentration at the cost of a 3% increased risk of it being rapid. To date there is very low certainty evidence for patient-important outcomes; the effects on mortality and health-related quality of life are unclear and do not rule out appreciable benefit or harm; there does not appear to be an important effect on cognitive function, but hospital stay may be slightly shorter, although available data are limited. Treatment decisions must weigh the value of an increase in serum sodium concentration against its short-term risks and unknown effects on patient-important outcomes. Evidence for other treatments is largely absent.Further studies assessing standard treatments such as fluid restriction or urea against placebo and one-another would inform practice and are warranted. Given the limited available evidence for patient-important outcomes, any study should include these outcomes in a standardised manner.

Current management of refractory ascites in patients with cirrhosis

Liver cirrhosis is a health problem worldwide, and ascites is its principal symptom. Refractory ascites is intractable and occurs in 5%-10% of all patients with ascites due to cirrhosis. Refractory ascites leads to a poor quality of life and high mortality rate. Ascites develops as a result of portal hypertension, which leads to water-sodium retention and renal failure. Various therapeutic measures can be used for refractory ascites, including large-volume paracentesis, transjugular intrahepatic portosystemic shunt, vasoconstrictive drugs, and an automated low-flow ascites pump system. However, ascites generally can be resolved only by liver transplantation. Because not all patients can undergo liver transplantation, traditional approaches are still used to treat refractory ascites. The choice of treatment modality for refractory ascites depends, among other factors, on the condition of the patient.

Alpha-2A Adrenoceptor Agonist Guanfacine Restores Diuretic Efficiency in Experimental Cirrhotic Ascites: Comparison with Clonidine

BACKGROUND

In human cirrhosis, adrenergic hyperfunction causes proximal tubular fluid retention and contributes to diuretic-resistant ascites, and clonidine, a sympatholytic drug, improves natriuresis in difficult-to-treat ascites.

AIM

To compare clonidine (aspecific α2-adrenoceptor agonist) to SSP-002021R (prodrug of guanfacine, specific α2A-receptor agonist), both associated with diuretics, in experimental cirrhotic ascites.

METHODS AND RESULTS

Six groups of 12 rats were studied: controls (G1); controls receiving furosemide and potassium canrenoate (G2); rats with ascitic cirrhosis due to 14-week CCl4 treatment (G3); cirrhotic rats treated (over the 11th-14th CCl4 weeks) with furosemide and canrenoate (G4), furosemide, canrenoate and clonidine (G5), or diuretics and SSP002021R (G6). Three rats of each group had their hormonal status and renal function assessed at the end of 11th, 12th, 13th, and 14th weeks of respective treatments.Cirrhotic rats in G3 and G4 gained weight over the 12th-14th CCl4 weeks. In G4, brief increase in sodium excretion over the 11th-12th weeks preceded worsening of inulin clearance and natriuresis (diuretic resistance). In comparison with G4, the addition of clonidine (G5) or guanfacine (G6) to diuretics improved, respectively, sodium excretion over the 11th-12th CCl4 weeks, or GFR and electrolytes excretion over the 13th-14th CCl4 weeks. Natriuretic responses in G5 and G6 were accompanied by reduced catecholamine serum levels.

CONCLUSIONS

α2A-receptor agonists restore glomerular filtration rate and natriuresis, and delay diuretic-resistant ascites in experimental advanced cirrhosis. Clonidine ameliorates diuretic-dependent natriuresis just for a short time.

A Physiologic Approach to the Pharmacogenomics of Hypertension

Hypertension is a multifactorial condition with diverse physiological systems contributing to its pathogenesis. Individuals exhibit significant variation in their response to antihypertensive agents. Traditional markers, such as age, gender, diet, plasma renin level, and ethnicity, aid in drug selection. However, this review explores the contribution of genetics to facilitate antihypertensive agent selection and predict treatment efficacy. The findings, reproducibility, and limitations of published studies are examined, with emphasis placed on candidate genetic variants affecting drug metabolism, the renin-angiotensin system, adrenergic signalling, and renal sodium reabsorption. Single-nucleotide polymorphisms identified and replicated in unbiased genome-wide association studies of hypertension treatment are reviewed to illustrate the evolving understanding of the disease's complex and polygenic pathophysiology. Implementation efforts at academic centers seek to overcome barriers to the broad adoption of pharmacogenomics in the treatment of hypertension. The level of evidence required to support the implementation of pharmacogenomics in clinical practice is considered.

Dose-dependency of clonidine's effects in ascitic cirrhotic rats: comparison with α1-adrenergic agonist midodrine

BACKGROUND & AIMS

Sympathetic nervous system (SNS) activation decreases response to diuretics, but both α1-adrenoceptor agonists and sympatholytic α2-adrenoceptor agonists are recommended in the management of ascitic cirrhosis. We intend to compare the effects of increasing doses of clonidine (α2-agonist) vs. midodrine (α1-agonist) in advanced cirrhosis.

METHODS

Renal function, mean arterial pressure (MAP), and hormonal status were measured in rats with ascitic cirrhosis due to 13-week CCl(4) administration (groups G1-G5), in control rats (Gc), and in rats with ascitic cirrhosis untreated (G6) or treated with daily diuretics (0.5 mg/kg furosemide plus 2 mg/kg K(+) -canrenoate during the 11(th) -13(th) weeks of CCl(4)) (G7). G1-G5 cirrhotic rats received daily, during the 11(th)-13(th) CCl(4) weeks: clonidine 0.3 μg only (G1), diuretics + clonidine 0.2 (G2), 0.5 (G3) or 1 μg (G4), and diuretics + midodrine 1 mg/kg b.w. (G5).

RESULTS

Cirrhotic rats in G1 or G2 had higher glomerular filtration rate, renal plasma flow and natriuresis than cirrhotic rats treated with diuretics (G7) (all P < 0.05). The addition of clonidine 0.2 μg to diuretics (G2 vs. G7) reduced serum norepinephrine (169 ± 71 ng/L vs. 523 ± 88 ng/L) and plasma renin activity (12 ± 3 ng/ml/h vs. 25 ± 5 ng/ml/h) (all P < 0.05). Midodrine did not improve the renal performance in ascitic rats treated with diuretics. In comparison to absolute cirrhotic controls (G6), MAP was lower in G4 and higher in G5 (all P < 0.05).

CONCLUSION

Low-dose α2-agonists improve natriuresis and reduce SNS function and hyper-aldosteronism without affecting arterial pressure in experimental ascitic cirrhosis treated with diuretics.

Pathogenesis of solute-free water retention in experimental ascitic cirrhosis: is vasopressin the only culprit?

Catecholamines trigger proximal tubular fluid retention and reduce renal excretion of solute-free water. In advanced cirrhosis, non-osmotic hypersecretion of vasopressin (antidiuretic hormone or ADH) is considered the cause of dilutional hyponatraemia, but ADH V2 receptor antagonists are not beneficial in long-term treatment of ascites. To test the hypothesis that water retention in experimental ascitic cirrhosis might depend primarily on adrenergic hyper-function, hormonal status, renal function and tubular free-water reabsorption (TFWR) were assessed in six groups of rats with ascitic cirrhosis: rats with cirrhosis due to 13-week CCl4 (carbon tetrachloride) administration (group G1); cirrhotic rats receiving daily diuretics (0.5 mg/kg furosemide plus 2 mg/kg K(+)-canrenoate) from the 11th to the 13th week of CCl4 (G2), diuretics associated with guanfacine oral prodrug (α2A-adrenergic receptor agonist and sympatholytic agent) at 2 (G3), 7 (G4) or 10 (G5) mg/kg, or with SSP-004240F1 (V2 receptor antagonist) at 1 mg/kg (G6). Natriuresis was lower in G1 than in G2, G4 and G6 (all P<0.05). Guanfacine, added to diuretics (i.e. G3 compared with G2), reduced serum noradrenaline from 423±22 to 211±41 ng/l (P<0.05), plasma renin activity (PRA) from 35±8 to 9±2 ng/ml/h (P<0.05) and TFWR from 45±8 to 20±6 μl/min (P<0.01). TFWR correlated with plasma aldosterone (r=0.51, P<0.01) and urinary potassium excretion (r=0.90, P<0.001). In ascitic cirrhosis, reduced volaemia, use of diuretics (especially furosemide) and adrenergic hyper-function cause tubular retention of water. Suitable doses of sympatholytic agents are effective aquaretics.

Correlation between changes in bodyweight and changes in ascites volume in liver cirrhosis patients with hepatic edema in short-term diuretic therapy

AIM

Although it is an important treatment challenge to treat ascites with diuretic therapy, no objective markers have been established to assess improvement of ascites. However, change in bodyweight has been used as a marker of change in ascites volume. Thus, we evaluated the relationship between changes in bodyweight and changes in ascites volume in liver cirrhosis patients with ascites.

METHODS

We calculated ascites volume in patients using the simple 5-point method by conventional computed tomography and conducted a correlation analysis between changes in bodyweight and changes in ascites volume as a part of our double-blind phase 3 trial of tolvaptan.

RESULT

Change in bodyweight (x-axis) was correlated with change in ascites volume (y-axis) in all included patients (r = 0.52). A strong correlation were observed between the changes in patients without lower limb edema (r = 0.61). These correlations between the changes were expressed by the following linear regression equations: y = -0.102 + 0.206x or y = -0.033 + 0.292x, respectively. Proportions of change in ascites volume to change in bodyweight were estimated to be nearly 30%. Therefore, bodyweight reduction was confirmed to lead to improvement in ascites.

CONCLUSION

Change in bodyweight can be an objective marker to assess improvement of hepatic edema in the short-term diuretic therapy in everyday clinical practice. Decrease in ascites volume was estimated to account for nearly 30% of bodyweight reduction.

Benzodiazepine-associated hepatic encephalopathy significantly increased healthcare utilization and medical costs of Chinese cirrhotic patients: 7-year experience

BACKGROUND AND OBJECTIVES

In cirrhosis, hypersensitivity to benzodiazepines (BZD) and precipitating hepatic encephalopathy (HE) have been reported. The aim of this study was to evaluate the safety, economic impact and modifiable factors that are associated with the excess risk of BZD-associated HE in cirrhotic patients.

METHODS

Between July 2005 and March 2012, 1,612 Chinese cirrhotic patients with and without using long-t 1/2-BZD or short-t 1/2-BZD were enrolled and followed up for 6 months.

RESULTS

Among BZD users, the per-person HE-related healthcare utilization and medical costs were found to have progressively increased from 2005 to 2012. Cirrhotic BZD users had a higher percentage of smoking, alcohol drinking, simultaneous consumption of non-BZD drugs, and had a higher incidence of non-cirrhotic chronic illness than non-BZD users. Multivariate analysis indicated that hypoalbuminemia (<3 g/dL), long-acting (t 1/2 > 12-h), high-dosage (>1.5 defined daily dose equivalents) and long-duration (>2-months) BZD use, carrier of variant genotypes (AG + GG) of GABRA 1 (rs2290732) and having the wild genotype (TT) of GABRG 2 (rs211037) were significant predictors of the development of BZD-associated HE in cirrhotic patients. Additionally, synergistic effects of the above significant predictors on BZD-associated HE risk could be identified.

CONCLUSIONS

Our study confirms the clinical and economic impact of BZD-associated HE in cirrhotic BZD-users. Accordingly, extra caution is needed when treating cirrhotic BZD users with the above risk factors in order to avoid the BZD-associated HE in cirrhotic patients.

Dose-finding trial of tolvaptan in liver cirrhosis patients with hepatic edema: A randomized, double-blind, placebo-controlled trial

AIM

Liver cirrhosis represents the end stage of any chronic liver disease, and it is associated with hepatic edema such as ascites. Many patients with ascites do not respond to diuretic therapy or require administration of diuretics at high doses that can cause adverse events. This 7-day, multicenter, double-blind trial of tolvaptan was designed to determine the optimal dose of tolvaptan for producing the intended pharmacological effect in hepatic edema.

METHODS

Liver cirrhosis patients with inadequate diuretic response despite having received a conventional diuretic therapy were enrolled in the trial. Participants were stratified randomly to four groups receiving tolvaptan at 7.5, 15 or 30 mg/day, or placebo as an add-on to conventional diuretics once daily for 7 days. Changes in bodyweight and abdominal circumference were analyzed. Serum sodium concentrations were measured. Safety assessment was performed.

RESULTS

Tolvaptan at 7.5-30 mg/day reduced bodyweight and abdominal circumference compared with placebo. Serum sodium concentrations remained within the normal range in all tolvaptan groups. Serious adverse events were not observed, and most common adverse event was thirst. Tolvaptan at 7.5 mg/day showed the maximum change in bodyweight and abdominal circumference together with preferable tolerability.

CONCLUSION

Tolvaptan at 7.5 mg/day was considered the optimal dose in liver cirrhosis patients with hepatic edema who showed inadequate response to conventional diuretics.

Midodrine and clonidine in patients with cirrhosis and refractory or recurrent ascites: a randomized pilot study

OBJECTIVES

Splanchnic arterial vasodilatation and subsequent activation of anti-natriuretic and vasoconstrictive mechanisms have an important role in cirrhotic ascites. The aim of this study was to evaluate the effects of midodrine, clonidine, and their combination on systemic hemodynamics, renal function, and control of ascites in patients with cirrhosis and refractory or recurrent ascites.

METHODS

Sixty cirrhotic patients with refractory or recurrent ascites were prospectively studied after long-term administration of clonidine (n=15) or midodrine (n=15), or both (n=15) plus standard medical therapy (SMT), or SMT alone (n=15), in a randomized controlled trial at a tertiary center.

RESULTS

A significant increase in urinary volume, urinary sodium excretion, mean arterial pressure, and decrease in plasma renin activity (P<0.05) was noted after 1 month. There was also a significant decrease in cardiac output (P<0.05) and increase in systemic vascular resistance (P<0.05) in all groups, except clonidine. There was no change in glomerular filtration rate and model for end-stage liver disease score. Midodrine and a combination of midodrine and clonidine plus SMT were superior to SMT alone in the control of ascites (P=0.05), and there was a trend towards better control of ascites in the clonidine group (P=0.1). The mortality and frequency of various complications were similar in all groups.

CONCLUSIONS

These results suggest that midodrine, clonidine, and their combination plus SMT improves the systemic hemodynamics without any renal or hepatic dysfunction, and is superior to SMT alone for the control of ascites. However, the combination therapy was not superior to midodrine or clonidine alone.

SNPs in genes encoding G proteins in pharmacogenetics

Heterotrimeric guanine-binding proteins (G proteins) transmit signals from the cell surface to intracellular signal cascades and are involved in various physiological and pathophysiological processes. Polymorphisms in the genes GNB3 (encoding the Gβ3 subunit), GNAS (encoding the Gαs subunit) and GNAQ (encoding the Gαq subunit) have been the primary focus of investigation. Polymorphisms in these genes could be associated with different complex phenotypes underlining that alterations in G-protein signaling can cause multiple disorders. G proteins present a point of convergence or ‘bottleneck’ between various receptors and effectors, thus making them a sensible tool for pharmacogenetic studies. The pharmacogenetic studies performed to date mostly demonstrate an association between G-protein polymorphisms and response to therapy or occurrence of adverse drug effects. Therefore, polymorphisms in genes encoding G-protein subunits may help to individualize drug treatment in various diseases with regard to both efficacy and safety.