Opioid peptides and primary biliary cirrhosis

Florid opioid withdrawal-like reaction precipitated by naltrexone in a patient with chronic cholestasis

Findings consistent with the hypothesis that increased central opioidergic tone contributes to the pruritus of cholestasis provide a rationale for treating this form of pruritus with opiate antagonists. However, initiation of therapy with an opiate antagonist in a cholestatic patient may precipitate a transient opioid withdrawal-like reaction. A woman with chronic cholestasis and disabling pruritus experienced severe transient opioid withdrawal-like reactions after oral administration of 12.5 and 2 mg naltrexone. Subsequently, naloxone was administered by intravenous infusion. Initially, the infusion rate was low and subtherapeutic. It was gradually increased to a rate known to be effective in inducing opioid antagonism. Oral naltrexone was then reintroduced without any reaction occurring. During the ensuing 12 months, while taking naltrexone, 25 mg daily, the patient has been completely free from pruritus. These observations strongly support the hypothesis that increased central opioidergic tone is a component of the pathophysiology of cholestasis.

Itch and atopic dermatitis: an overview

Itching is the hallmark of atopic dermatitis, and a vicious itch-scratch circle is easily established. Itching and scratching are important factors in the maintenance of symptoms and can have a significant impact on the sufferer's quality of life. The pathophysiology of itch in atopic dermatitis is still not understood. Unlike in urticaria, histamine is not considered to be a major pruritogen in atopic dermatitis. In fact, the peripheral pruritogens and their cellular origin(s) still remain to be identified in this disease. Various treatments are used to relieve the skin inflammation, itching, and scratching in patients with atopic dermatitis, but no specific antipruritic therapy is available. However, several nonspecific therapies can effectively break the vicious itch-scratch circle. The use of topical corticosteroids and emollients and the elimination of individual trigger factors are still first-line measures.

Oral nalmefene therapy reduces scratching activity due to the pruritus of cholestasis: a controlled study

BACKGROUND

Intravenous naloxone frequently ameliorates the pruritus of cholestasis, but its low oral bioavailability precludes its use as a long-term therapy. Nalmefene is an orally bioavailable opiate antagonist.

OBJECTIVE

We assessed the efficacy of oral nalmefene in ameliorating the pruritus of cholestasis.

METHODS

In a prospective controlled study conducted in a tertiary referral hospital, 11 patients with generalized pruritus complicating chronic liver disease were randomized to receive either nalmefene or placebo in a double-blinded fashion for 2-month periods. Scratching activity was measured continuously for 24-hour periods at baseline and at the end of each treatment period.

RESULTS

Data on 8 patients who received at least 1 course of nalmefene were available for comparison with corresponding control data, which consisted of observations obtained during a course of placebo and/or at baseline. Nalmefene therapy was associated with a 75% reduction in the geometric mean hourly scratching activity (P <.01) and a decrease in the mean of a visual analogue score of the perception of pruritus in all 8 patients (mean decrease 77%, P <.01).

CONCLUSION

Oral administration of nalmefene can ameliorate pruritus complicating chronic liver disease.

Primary biliary cirrhosis and primary sclerosing cholangitis

Primary biliary cirrhosis and primary sclerosing cholangitis are the most common chronic cholestatic liver diseases in adults that lead to biliary cirrhosis and its inherent complications such as portal hypertension and liver failure. Although important advances in the understanding of the pathogenesis of these conditions have been accomplished in the last two decades, much work is needed to uncover the interaction of genetic and immunologic mechanisms involved in their pathogenesis. Ursodeoxycholic acid at dosage of 13 to 15 mg/kg/d is the only agent that can currently be recommended in the treatment of PBC. No medical therapy aimed at disrupting disease progression is available for patients with primary sclerosing cholangitis, although several agents with different properties are currently under evaluation. Liver transplantation is the treatment of choice for patients with primary biliary cirrhosis and primary sclerosing cholangitis with end-stage liver disease.

Benign recurrent intrahepatic cholestasis

Benign recurrent intrahepatic cholestasis is a rare autosomal recessive disorder characterized by repeated episodes of intense pruritus and jaundice. Each attack lasts from several weeks to months before resolving spontaneously. Patients are completely asymptomatic for months to years between symptomatic periods. The disorder does not lead to progressive liver disease. Although attacks seem to be associated with a viral prodrome, an inciting viral agent or toxin has not been defined. Genetic studies have mapped the defect of this disorder to the long arm of chromosome 18 and a gene that codes for a P-type ATPase, which appears to be involved in aminophospholipid transport. Therapy during symptomatic periods is supportive and aimed at relief of severe pruritus until the episode resolves spontaneously.

Further studies on aminopeptidase-M in blood in children with cholestatic liver diseases and viral hepatitis

Aim of this study was to determine and further characterize the serum aminopeptidase-M in children with liver diseases. Based on our new assay, we have shown two fractions of the enzyme. Activity of the first fraction is expressed in undiluted serum at pH adjusted from 8.5 (pH of storaged serum) to 7.4. Activity of the second fraction (cryptic activity) appears in the serum (pH 7.4) as a result of dilution and/or addition of aniline naphthalene sulfonic acid. In children with Alagille syndrome, extrahepatic biliary duct atresia, Byler's disease, and acute hepatitis due to hepatitis B virus infection, activities of both fractions are highly elevated as compared to healthy children or those with chronic viral hepatitis. Moreover, serum aminopeptidase-M seems to reflect other aspects of the pathological process than those reflected by the alanine aminotransferase and gamma-glutamyltranspeptidase. Due to increased activity and broad substrate specificity, the enzyme seems to be also a cofactor of cholestasis and hepatitis.

The opioid peptide analog D-Ala2-Met-enkephalinamide decreases bile flow by a central mechanism

The existence of an opioid central pathway that may regulate bile secretion was explored by studying the effect of the intracisternal (i.c.) administration of the opiate D-Ala2-Met-enkephalinamide (DAME) on bile secretion in anesthetized male rats. The i.c. administration of DAME was associated with a dose-related decrease in bile flow that ranged from 12% to 41%, which was prevented by the opiate antagonist naloxone. Bicarbonate secretion into bile decreased significantly after i.c. DAME. Chemical adrenergic denervation and cholinergic pharmacological blockade with atropine did not prevent the DAME-induced decrease in bile flow. The data support the existence of an opioid-mediated pathway that starts in the brain and that contributes to the regulation of bile secretion.

Opioid receptor ligands in human hepatic encephalopathy

BACKGROUND/AIMS

Opioid peptides may contribute to some of the manifestations of hepatic encephalopathy. To address the role of the opioid system in the pathogenesis of hepatic encephalopathy, three representative opioid ligands were measured in plasma and cerebrospinal fluid of patients with hepatic encephalopathy.

METHODS

Plasma and cerebrospinal fluid were obtained in three groups of patients: group 1: patients with hepatic encephalopathy; group 2: patients with lumbar back pain; group 3: healthy controls. Met-enkephalin, leu-enkephalin and beta-endorphin levels were measured in extracted plasma and cerebrospinal fluid samples by radioimmunoassay.

RESULTS

Plasma met-enkephalin levels were 656% (p<0.05) and 301% (p<0.05) and cerebrospinal fluid met-enkephalin levels were 1481% (p<0.01) and 645% (p<0.05) higher when compared to healthy control and pain control patients, respectively. Although plasma and cerebrospinal leu-enkephalin levels were elevated in patients with hepatic encephalopathy, the increases were not statistically significant. Plasma and cerebrospinal beta-endorphin levels were similar in the three study groups.

CONCLUSIONS

The results of this study support accumulating data on the role of the delta opioid receptor ligand met-enkephalin in the pathogenesis of hepatic encephalopathy, and provide a rationale for the use of opioid receptor antagonists in the treatment of hepatic encephalopathy.

Opioid antagonists in the treatment of pruritus from cholestatic liver disease

The theory that pruritus from cholestasis is due to increased opiate tone appears to have merit, based on the results of the clinical trials presented above. However, although opioid antagonists relieve itching to a large extent, the itching usually is not abolished completely. Several factors may explain this lack of complete relief. The doses used in the clinical trials may have been insufficient, or duration of therapy may have been short. It is also possible that nonopioid mechanisms contribute to pruritus from cholestasis. Although effective, naloxone therapy has several limitations for long-term use, including a short half-life and large first-pass metabolism, which necessitates parenteral administration. Intravenous administration is clearly not practical for a chronic disease. Nalmefene treatment has several advantages over naloxone, with both prolonged duration of action and increased potency at the opioid receptor level. However, nalmefene is available only as a parenteral product in the US. The nalmefene studies are limited by their small sample size and short follow-up periods. Additionally, two of the studies are available in abstract form only. Based on two clinical studies, naltrexone therapy appears promising. Gradual dose titration from 25 mg/d up to a maximum of 50 mg/d may minimize withdrawal reactions. Further long-term clinical trials using objective measures that compare opioid antagonists with other therapies are needed to clearly establish the role of these agents. Potential tachyphylaxis from long-term use of opioid antagonists requires further investigation. Combination therapy may also be required, since monotherapy with either opioid antagonists or other therapies have failed to completely relieve the pruritus caused by cholestasis. Given the potential for severe withdrawal reactions, opioid antagonists should be reserved for patients refractory to other treatments.

Hypothesis: taste disorders in patients with liver disease may be mediated in the brain: potential mechanisms for a central phenomenon

Patients with liver disease experience alterations in the sense of taste. There is increasing evidence to suggest that some of the symptoms associated with liver disease (e.g., pruritus) are mediated in the brain. A hypothesis for a brain-mediated mechanism underlying taste alterations in hepatic disorders is presented in this paper.

The management of primary sclerosing cholangitis

Primary sclerosing cholangitis is a chronic cholestatic liver disease characterized by a progressive, obliterating fibrosis of the intrahepatic and extrahepatic bile ducts. The pathogenesis of PSC is unknown, but it is thought to be an immune-mediated disease. Although the role of cupruretics, immunosuppressants (corticosteroids, azathioprine, tacrolimus, methotrexate), antifibrogenic agents, and ursodeoxycholic acid in the treatment of primary sclerosing cholangitis is reviewed, none of these agents has been shown to retard or reverse the rate of disease progression. Of these therapies, ursodeoxycholic acid at high doses looks the most promising, but large trials are needed to establish whether treatment with high-dose ursodeoxycholic acid influences the morbidity and mortality associated with primary sclerosing cholangitis.

The pruritus of cholestasis: evolving pathogenic concepts suggest new therapeutic options

Pruritus is a distressing symptom experienced by a large proportion of patients with cholestasis. The cause of this form of pruritus is unknown, and therapy tends to be empirical and unsatisfactory. This article discusses the emerging role of the brain and neurotransmitter systems in the pathogenesis of the pruritus of cholestasis and emphasizes the importance of the application of quantitative methodology in clinical trials of therapies for the pruritus of cholestasis.

Open-label trial of oral nalmefene therapy for the pruritus of cholestasis

The aims of this study were to determine whether long-term oral administration of the opiate antagonist nalmefene is associated with any beneficial effects in patients with pruritus secondary to cholestatic liver disease and to assess the safety of long-term administration of this drug to these patients. Fourteen patients with unrelieved chronic pruritus of cholestasis were studied. Scratching activity, independent of limb movements, was recorded continuously for 24-hour periods before and during treatment with an initial ameliorating dose of nalmefene. Simultaneously, during these periods, visual analogue scores (VASs) of pruritus were recorded every 4 hours while patients were awake. The dose of nalmefene, which initially was 2 mg orally twice daily, was increased during the study, usually until a satisfactory clinical response was achieved. Five patients experienced a transient opioid withdrawal-like reaction that did not preclude continuing with nalmefene therapy. Serum biochemical indices of cholestasis did not change appreciably during treatment. Thirteen patients reported amelioration of the perception of pruritus on nalmefene. In 5 patients, exacerbations of pruritus occurred approximately 4 weeks after an initial ameliorating dose had been reached; these exacerbations were managed by increasing the dose. Baseline mean values for VAS and scratching activity were higher than corresponding means during nalmefene therapy in 13 (P = .002) and 12 (P = .013) patients, respectively. Possible tolerance to nalmefene occurred in 3 patients. Three patients experienced marked exacerbation of pruritus after nalmefene therapy was suddenly discontinued. Blood levels of nalmefene were consistent with normal pharmacokinetics of the drug. These results suggest that nalmefene may have a favorable risk-to-benefit ratio when it is administered orally long-term to patients with the pruritus of cholestasis.

Naltrexone: a case report of pruritus from an antipruritic

Intense, generalized pruritus associated with mycosis fungoides was relieved using subcutaneous naloxone but intensified when changed to the new oral opioid antagonist, naltrexone. Rechallenge again led to worsening in pruritus. This unexpected adverse effect is surprising as naltrexone and naloxone are currently thought to work via similar opioid receptor binding. The worsening of the itch may have been due to adaptation in opioid receptor expression induced by prolonged naloxone therapy, possibly highlighting differential opioid receptor affinity between naltrexone and naloxone, or may have represented an idiosyncratic adverse reaction. Naltrexone and naloxone have been reported to reduce pruritus due to cholestasis, uraemia, morphine epidurals, and possibly atopic dermatitis and urticaria. Naltrexone has the convenience of oral administration and a longer half-life. The role of the opioid system and naltrexone in pruritus is reviewed.

Basal total opioid peptide release in the striatum of rats with cholestasis from bile duct resection: a study by the use of in vivo microdialysis

The opiate withdrawal-like reaction experienced by patients with cholestatic liver disease after the ingestion of the opiate antagonist nalmefene led to the hypothesis that increased opioidergic neurotransmission/neuromodulation in the central nervous system (CNS) contributes to the pathophysiology of cholestasis. The state of antinociception, which is stereospecifically reversed by naloxone, documented in rats with cholestasis from bile duct resection supports this hypothesis. To further study the opioid system in this animal model of cholestasis, we studied the release of endogenous opioid peptides into the extracellular fluid of the dorso-lateral striatum by the technique of in-vivo microdialysis. Total opioid peptide concentration in the dialysate was measured by a solid phase radioimmunoassay with an antibody directed against the N-terminus of the Tyr-Gly-Gly-Phe-X amino acid sequence after acetylation. Basal total opioid peptide release was significantly higher after surgery in both sham resected and bile duct resected animals. However, basal (unstimulated) total opioid peptide release in the striatum of rats was not altered by cholestasis. It is inferred that the opioidergic abnormalities of cholestasis are not associated with an appreciable increase in the release of endogenous opioids into the extracellular fluid of the striatum. Abnormal processing of specific opioid peptides in cholestasis however, cannot be excluded.

Effect of liver cirrhosis on the systemic availability of naltrexone in humans

BACKGROUND/AIMS

Naltrexone is a competitive opiate antagonist with high hepatic extraction. It is used for detoxification treatment for heroin addicts and has been proposed as a possible treatment of pruritus in cholestasis. Such patients are likely to have impaired liver function, underscoring the need to understand the pharmacokinetic behavior of naltrexone in liver disease. These studies were undertaken to evaluate the effect of liver cirrhosis on the plasma time-course of naltrexone.

METHODS

A total of 18 patients were investigated: seven migraine patients with normal liver function regarded as controls and 11 patients with liver cirrhosis (six with decompensated disease and five with preserved liver function). A bolus of 100 mg of naltrexone was administered orally in the morning, after an overnight fast. Blood samples were taken in basal conditions and at fixed intervals, up to 24 h after administration. Serum levels of naltrexone and of its major active metabolite, 6 beta-naltrexol, were assayed by reversed-phase HPLC analysis.

RESULTS

In control subjects, circulating concentrations of naltrexone were always much lower than those of 6 beta-naltrexol (area under the curve: naltrexone, 200 +/- 97 ng/ml x 24 h; 6 beta-naltrexol, 2467 +/- 730 ng/ml x 24 h, p < 0.01). In severe cirrhosis serum levels of 6 beta-naltrexol increased more slowly, so that circulating levels of naltrexone during the first 2-4 h after drug intake were higher than those of 6 beta-naltrexol (6 beta-naltrexol/naltrexone ratio at 2 h: controls, 10.91 +/- 4.80; cirrhosis, 0.39 +/- 0.18, p < 0.01). The area under the curve for naltrexone (1610 +/- 629 ng/ml x 24 h) was significantly greater than in controls, whereas that for 6 beta-naltrexol (2021 +/- 955 ng/ml x 24 h) was not significantly different. Patients with compensated cirrhosis showed an intermediate pattern. No differences in elimination half-life of the two drugs were detected among the groups.

CONCLUSIONS

Our data suggest the occurrence of important changes in the systemic availability of naltrexone and 6 beta-naltrexol in liver cirrhosis; such alterations are consistent with lesser reduction of naltrexone to 6 beta-naltrexol and appear to be related to the severity of liver disease. This must be considered when administering naltrexone in conditions of liver insufficiency.

Decreased patient analgesic requirements after liver transplantation and associated neuropeptide levels

BACKGROUND

Decreased morphine requirements have been reported after liver transplantation when compared with other types of major abdominal surgery. The aim of this study was to examine plasma concentrations of three neuropeptides involved in pain modulation-metenkephalin (ME), beta-endorphin (BE), and substance P (SP)-in patients undergoing orthotopic liver transplantation (OLT) and in control patients undergoing other liver operations. We then compared the postoperative analgesic requirements in these two groups of patients.

METHODS

Plasma levels of ME, BE, and SP were measured by radioimmunoassay at preincision, preemergence, and for 3 days after operation in 13 patients undergoing OLT and in 10 control patients. Patient-controlled analgesia morphine delivery was recorded for all patients postoperatively, and plasma morphine, its metabolites, and patient pain and sedation scores were also measured.

RESULTS

ME levels were elevated in all OLT patient samples when compared with control patient samples. BE levels were not significantly different at any time. SP levels were significantly decreased only in preincision and preemergence OLT patient samples. Total patient-controlled analgesia morphine delivered during the first 3 postoperative days was significantly less in OLT patients (70+/-8 mg) than in control patients (101+/-12 mg). Plasma morphine, morphine-3-glucuronide, and morphine-6-glucuronide levels were decreased in OLT patients, however, statistical significance was seen only in the morphine-6-glucuronide results.

CONCLUSIONS

We have shown that postoperative analgesic requirements are decreased in OLT patients, and we suggest that associated increased peripheral ME levels may be contributing to this decreased requirement. Based on our results, circulating BE and SP are less significant factors affecting postoperative analgesic requirements.

Review article: the management of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by a progressive obliterating fibrosis of the intrahepatic and extrahepatic bile ducts. The pathogenesis of PSC is poorly understood but it is thought to be an immune-mediated disease. The optimal therapy which successfully improves symptoms, delays progression towards liver failure and transplantation and prevents the onset of cholangiocarcinoma remains elusive. Although current treatments are used to manage cholestasis and its consequences and some of the more general complications of the disease, none of the current therapeutic agents have been shown to retard and reverse the rate of disease progression. The role of cupruretics, corticosteroids, methotrexate, antifibrogenic agents and ursodeoxycholic acid in the treatment of PSC is reviewed. Orthotopic liver transplantation remains the only therapeutic option for advanced PSC but the timing of transplantation remains controversial and the possibility of recurrence of the disease in the graft is increasingly recognised. It is likely that greater insight into the pathogenetic mechanisms involved in PSC will allow therapy to be targetted more specifically at the biliary epithelium.

Inhibition by L-NA, a nitric oxide synthase inhibitor, of naloxone-precipitated withdrawal signs in a mouse model of cholestasis

Following the naloxone administration in bile duct resected animals, striking opioid withdrawal signs are observed due to increased opioidergic tone. Pretreatment of animals with L-nitro arginine, a nitric oxide synthase inhibitor, reduces the naloxone-precipitated withdrawal signs as well as increase the antinociception. The results of this study support evidence for the involvement of the L-arg-nitric oxide pathway in opioidergic-dependent manifestation of cholestasis in an animal model.

Pruritus--itching for a cause and relief?

The mechanisms of pruritus, an unpleasant irritation on the skin that provokes an urge to scratch, are reviewed. Whilst symptomatic treatment is only partially effective, antihistamines remain the first choice of treatment. However, recent novel treatment using opiate antagonists, propofol (subhypnotic doses) and serotonin antagonists offer attractive alternatives.

Hepatic concentrations of proenkephalin-derived opioids are increased in a rat model of cholestasis

The liver of adult rats with cholestasis secondary to bile duct resection has been shown to express the proenkephalin gene and, by immunohistochemical stains, to contain met-enkephalin. To further study hepatic opioids in cholestasis, concentrations of proenkephalin-derived endogenous opioids were measured in a rat model of cholestasis by the use of radioimmunoassays. The specificity of the immunoreactivity detected by the assays was confirmed by high performance liquid chromatography (HPLC). In adult male rats with cholestasis due to BDR, the concentrations of three proenkephalin-derived opioid peptides were increased. Specifically, the mean hepatic concentrations of met-enkephalin, Met-Enk-Arg6-Phe7 and leu-enkephalin were 2.5 (p < 0.005), 2.1 (p < 0.005) and 2.5 (p < 0.01) fold higher than the corresponding mean for controls. These findings provide further independent evidence that opioid peptides accumulate in the liver in a model of cholestasis and are consistent with de novo synthesis of opioid peptides occurring in the cholestatic liver. This phenomenon may have relevance to the altered function of the opioid system in cholestasis and to the role of the liver as a neuroendocrine organ.

The pruritus of cholestasis

The pruritus of cholestasis is a difficult clinical problem to manage. The pathogenesis of this symptom is unknown. All conventional therapies have been unsuccessful in isolating a particular group of substances that could be implicated as direct or indirect causative agents. It should be emphasized that nonspecific treatment modalities that lower the plasma concentrations of a variety of substances (such as cholestyramine, colestipol, charcoal hemoperfusion, plasmapheresis, partial external diversion of bile, and drugs that induce hepatic enzymes), can potentially ameliorate the pruritus of cholestasis by lowering the circulating levels of an undefined pruritogen or a factor responsible for inducing the primary mechanism of the pruritus. The encouraging results reported by the use of antibiotic therapy for this condition merits investigation. Increased opioidergic neurotransmission is part of the syndrome of cholestasis and it contributes, at least in part, to the pruritus associated with it. Opiate antagonists seem to be an effective alternative therapy for some patients. Recent preliminary reports suggest that other neurotransmitter systems, eg, serotoninergic, may be involved in the pruritus of cholestasis. The need for quantitation of scratching activity cannot be over emphasized. The use of quantitative methodology offers the opportunity to facilitate the study of scratching behavior that is a biological phenomenon secondary to liver disease.

Increased met-enkephalin plasma levels in hemodialysis patients with or without pruritus

Met-enkephalin plasma levels were measured in 21 hemodialysis patients with or without pruritus. The mean value was significantly increased in the total of the patients compared with that in ten healthy subjects. There was, however no correlation between met-enkephalin levels and the degree of pruritus. The findings suggest that the opioid system may be activated in this condition, although the relevance of this endogenous opioid peptide to pruritus remains to be determined.

Microinjection of morphine into the rat medullary dorsal horn produces a dose-dependent increase in facial scratching

It has been proposed that opioids act at the level of the medulla to produce facial pruritus. Supporting this hypothesis, microinjection of mu-opioid receptor agonists into the medullary dorsal horn (MDH; trigeminal subnucleus caudalis) of monkeys produces facial scratching behavior. The present study sought to establish a rodent model of opioid-induced facial pruritus. To this end, morphine (0.1, 0.3 or 1.0 micrograms/0.2 microliter) or saline (0.2 microliter) was unilaterally microinjected into the MDH of male Sprague-Dawley rats. Behavior for the 20 min preceding and the 80 min after this microinjection was videotaped. Morphine produced dose-dependent increases in facial scratching behavior ipsilateral to the microinjections with the peak effect at 30-40 min after microinjection. Facial scratching continued for the entire 80 min post-microinjection test period. Morphine also produced a lesser degree of facial scratching contralateral to the microinjections. Increases in facial scratching ipsilateral to the microinjection of 0.3 microgram morphine into the MDH were attenuated by 0.4 mg/kg s.c. naloxone. These findings support the hypothesis that the MDH is a critical site of action of opioid agonists in producing facial pruritus.

Increased opioid binding to peripheral white blood cells in a rat model of acute cholestasis

BACKGROUND/AIMS

Endogenous opioids accumulate in plasma in cholestasis. Furthermore, immune cells have opioid receptors, and endogenous opioids have immunomodulatory effects. This study examined the expression of opioid receptors on peripheral white blood cells in rats with acute cholestasis after bile duct resection (BDR).

METHODS

Five days after surgery, white blood cells were isolated from peripheral blood. To determine total opioid binding, cells from either BDR or sham-resected rats were incubated with a fluorescently labeled opioid receptor antagonist. Specific opioid binding was determined by preincubating the cells with a 100-fold molar excess of unlabeled naltrexone or with one of two opioid receptor agonists: (D-Ala2, D-Leu5)-enkephalin (delta receptor) or (D-Ala2, MePhe4, Gly-ol5)enkephalin (mu receptor). The proportion of neutrophils, lymphocytes, and monocytes with specific delta or mu opioid receptors was determined by flow cytometric analysis.

RESULTS

Opioid receptors on neutrophils were unaffected by BDR, whereas the lymphocyte population of BDR rats had an increased binding to delta receptors (2.6% +/- 1.1% for sham vs. 7.3% +/- 1.4% for BDR; P < 0.02) and monocytes from BDR rats had an increased binding to mu receptors (7.7% +/- 0.9% for sham vs. 17.9% +/- 2.3% for BDR; P < 0.0001).

CONCLUSIONS

The selective increase of delta-receptor binding on lymphocytes and mu-receptor binding on monocytes suggests that, in acute cholestasis, opioid-mediated effects on white blood cell function may be altered.

Relief of cholestatic pruritus by a novel class of drugs: 5-hydroxytryptamine type 3 (5-HT3) receptor antagonists: effectiveness of ondansetron

The objective of the present study was to determine whether ondansetron, a specific serotonin type 3 receptor antagonist (5-HT3), relieves cholestatic pruritus in patients resistant to conventional antipruritic therapy (antihistamines and cholestyramine). In a placebo-controlled study the acute effect of an intravenous injection of ondansetron (4 mg, 8 mg) or placebo (NaCl solution) was tested in 10 patients (41-66 years of age; 4 men, 6 women) with cholestatic itch. A successful treatment was assessed when the intensity of itch was reduced by 50% or more within 2 h after injection of ondansetron. Intensity of itch was determined by the patients on a visual rating scale from 0 to 10. Ondansetron reduced or abolished pruritus within 30-60 min after injection. A 50% reduction of the intensity of itch was observed up to 6 h after injection of 8 mg. The effect was reproducible in the same patient. In conclusion ondansetron is effective in the treatment of cholestatic itch. Serotonin may participate in the generation and/or sensation of cholestatic pruritus.

Hepatic disorders. Features and appropriate management

The spectrum of liver disease is extremely wide, with many of the underlying disorders having acute and chronic presentations. Most of the underlying pathogenetic mechanisms are accounted for by autoimmune disease, viral infection and toxic insult. The management strategy of any liver disease is a combination of treating the symptoms and complications that arise, as well as drug therapies relevant to the specific underlying diagnosis. Encephalopathy, ascites, spontaneous bacterial peritonitis, variceal bleeding and pruritus are the main complications at which drug therapy is directed, although in some cases it represents only 1 aspect of the overall management. Drug therapy per se is largely ineffective in acute liver failure with the possible exception of acetylcysteine, but many drugs are used in the management of the constituent components of this complex medical emergency. Treatments for specific liver conditions are expanding, especially in the areas of autoimmune and viral disease. The increasing availability and success of liver transplantation has tended to change the emphasis of management, and it is often not appropriate to exhaust the treatment options before referring the patient for transplantation. A comprehensive review of all liver disease is beyond the scope of this article, but hopefully the important principles of management and commonly occurring clinical decisions are discussed.

Tetracycline-induced bile duct paucity and prolonged cholestasis

Acute self-limited liver disease has been associated with tetracycline use. However, severe prolonged cholestatic hepatitis and bile duct paucity have not been previously attributed to tetracyclines. Hepatitis, characterized by prolonged jaundice, severe pruritus, and moderate increased transaminase values, occurred within 2 months of ingesting tetracyclines in two female patients. Serum bilirubin levels normalized 12 and 34 months after tetracycline ingestion. Liver histology revealed bile duct paucity, severe cholestasis, and minimal necrosis and inflammation. Tetracyclines may infrequently induce bile duct paucity and prolonged, severe, and reversible cholestasis.

Raised beta-endorphin serum levels in children with atopic dermatitis and pruritus

Atopic dermatitis (AD) is a pruritic cutaneous inflammatory condition. As pruritus and pain are very close symptoms, we determined the beta-endorphin serum concentrations in 21 atopic children with pruritus (group A) and 20 children with healed AD without pruritus (group B). Twenty-five healthy school children were the control group. The beta-endorphin serum concentrations (14.95 +/- 2.75 pmol/l) in group A were statistically (P < 0.001) elevated in our patients compared to controls (8.85 +/- 2.39 pmol/l) whereas these in group B were not elevated (9.4 +/- 2.46 pmol/l). We suggest that the elevated beta-endorphin concentrations in atopic patients with pruritus confirm the hypothesis that there is an increased activity of their opioid system and that an opioid antagonist might block itching which is their major clinical symptom.

Thalidomide as therapy for primary biliary cirrhosis: a double-blind placebo controlled pilot study

Thalidomide has been reported to be effective in treating graft-versus-host disease, a condition with many clinical and pathological similarities to primary biliary cirrhosis. We performed a double-blind, placebo-controlled pilot study to assess the efficacy of thalidomide in 18 patients with biopsy-proven primary biliary cirrhosis (10 thalidomide, 8 placebo). Each patient was treated for 6 months and had a liver biopsy before and after treatment. Side effects, particularly sedation and fatigue, were more common on thalidomide and two patients were withdrawn from this group. There were no improvements in liver function tests or in liver histology, assessed morphometrically. A number of patients treated with thalidomide reported an improvement in pruritus. This study suggests that thalidomide is unlikely to be effective in altering the natural history of primary biliary cirrhosis.

Flumecinol for the treatment of pruritus associated with primary biliary cirrhosis

OBJECTIVE

To determine whether flumecinol (3-trifluoromethyl-alpha-ethylbenzhydrol, Zixoryn) is effective in ameliorating pruritus of cholestasis, particularly in primary bilary cirrhosis.

METHODS AND RESULTS

50 patients (46 with primary biliary cirrhosis, PBC) took oral flumecinol 600 mg or identical placebo once weekly for 3 weeks. Patients assessed pruritus by scoring a daily 100 mm visual analogue scale (VAS; 0 = no itch, 100 = severe, continuous, day and night intolerable itch). Quality of life was similarly measured. Patients scored the VAS daily for a 7-day baseline and for a further 21 days. Subjectively, pruritus improved in 13 of 24 on flumecinol and 10 of 26 on placebo (chi 2 = 1.24, P = 0.27). Median difference in fall in VAS pruritus score between baseline week (mean score for each individual used) and the last week was 8.0 [95% confidence interval (CI) -2.1 to 20.8] and for VAS quality of life was 5.0 (95% Cl 0.4 to 13.0) both in favour of flumecinol over placebo. Later, 19 patients (all PBC) were randomised to flumecinol 300 mg or placebo daily for 3 weeks. Subjectively, pruritus improved in 7 of 10 on flumecinol and 1 of 9 on placebo (Fisher's exact test, P = 0.02). Median difference in fall in VAS pruritus score was 19.8 mm (95% CI 3.3 to 40.7 mm) in favour of flumecinol over placebo and for quality of life was 3.5 mm (95% Cl -5.9 to 24.9 mm). Flumecinol did not significantly affect liver function tests, antipyrine clearance or serum total bile acids, and was not associated with any significant side-effects.

CONCLUSION

Flumecinol was safe at the above doses and short term treatment with 300 mg daily, significantly ameliorated pruritus in primary biliary cirrhosis.

A two year controlled trial examining the effectiveness of ursodeoxycholic acid in primary biliary cirrhosis

Forty-six patients with primary biliary cirrhosis from a single centre were studied in a randomized placebo-controlled trial to determine the effectiveness of ursodeoxycholic acid (UDCA) over a 2 year period. The two groups were well-matched at baseline. For each parameter, by calculating the difference between the median changes with time between the UDCA group and the placebo group, it was found that from entry, with respect to placebo, there were differences between median changes (MCD) favouring the UDCA group in bilirubin (MCD 5 mumol/L [95% confidence interval (CI) 1 to 12] at 1 year and 5 mumol/L (95% CI 1 to 9) at 2 years), alkaline phosphatase MCD 242 iu/L (95% CI 107 to 360) at 1 year and 268 iu/L (95% CI 146 to 424) at 2 years and aspartate aminotransferase MCD 26 iu/L (95% CI 12 to 41) at 1 year and 37 iu/L (95% CI 16 to 64) at 2 years. Within the UDCA group, there was long-term fall in alkaline phosphatase [median fall 116 iu/L (95% CI 93 to 378) at 2 years and aspartate aminotransferase [median fall 18 iu/L (95% CI 6 to 47) at 2 years; however, the major change in bilirubin was a modest rise over 2 years in the placebo group [median rise 2 mumol/L (95% CI 1 to 9)]. Changes in albumin, prothrombin ratio and immunoglobulins were generally minor and not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholestasis in the male rat is associated with naloxone-reversible antinociception

Clinical observations have suggested that cholestasis is associated with increased neurotransmission mediated by the opioid system in the central nervous system. As opiate agonists (e.g. morphine) mediate analgesia, increased opioidergic tone in cholestasis should be associated with a decreased response to pain. To test this hypothesis, the response of rats with acute cholestasis to a nociceptive stimulus was measured by the use of the tail-flick test, an extensively validated assay for measuring opiate-induced antinociception. Five and 7 days after bile-duct resection, the mean tail-flick latency was longer than before surgery (p < 0.05), whereas the corresponding means for unoperated and sham-resected controls were not significantly different from their respective baseline values. The increase in the mean tail-flick latency in the bile-duct resection group was reversed by (-)-naloxone (1 mg/kg subcutaneously), but not by its enantiomer (+)-naloxone (10 mg/kg subcutaneously) (p < 0.001). The stereoselective reversal of antinociception in cholestasis by naloxone indicates that this phenomenon is opioid-receptor mediated. In contrast, prolongation of the mean TFL found in the rat model of thioacetamide-induced acute hepatocellular necrosis was not reversed by (-)-naloxone, indicating that antinociception in this model is not opioid mediated. These findings provide support for the hypothesis that cholestasis is associated with increased opioidergic tone.

Suppression of hypothalamic-pituitary-adrenal axis responsiveness to stress in a rat model of acute cholestasis

Cholestatic patients undergoing surgery have increased mortality and demonstrate clinical features suggestive of adrenal insufficiency. To examine whether cholestasis influences the status of the hypothalamic-pituitary-adrenal axis, we evaluated rats with acute cholestasis caused by bile duct resection (BDR) and sham-operated and unoperated controls. Basal unstressed plasma concentrations of ACTH and corticosterone were similar in BDR and sham-operated and unoperated control rats. However, exposure of BDR rats to saturated ether vapor resulted in significantly less ACTH and corticosterone release in plasma than in the control animals. To understand the mechanism(s) of decreased HPA axis responsiveness to ether stress in cholestasis, we administered corticotropin-releasing factor (CRF) and measured hypothalamic content, mRNA levels and in vitro secretion of CRF and arginine vasopressin (AVP), the two principal secretagogues of ACTH. In BDR animals, ACTH responses to CRF were decreased and hypothalamic content of CRF and CRF mRNA expression in the paraventricular nucleus were decreased by 25 and 37%, respectively. Furthermore, CRF release from hypothalamic explants of BDR rats was 23% less than that of controls. In contrast to CRF, hypothalamic content of AVP was 35% higher, AVP mRNA in the paraventricular nucleus was increased by 6.6-fold, and hypothalamic explant release of AVP was 24% higher in BDR rats than in control animals. Pituitary ACTH contents were similar in BDR and sham resected rats, but higher than unoperated controls. These findings demonstrate that acute cholestasis in the rat is associated with suppression of hypothalamic-pituitary-adrenal axis responsiveness to stress and demonstrate a dissociation between mechanisms of ACTH regulation mediated by CRF and AVP.

Pruritus and cholestasis: therapeutic options

The pathogenesis of pruritus of cholestasis remains unclear. Bile salts do not appear to be the sole prurogens in cholestasis. Histaminergic pathways may be involved, and central opiate receptor processes seem much more important than has previously been recognized. The therapeutic options for relief of cholestatic pruritus are summarized in Table 2. Resins such as cholestyramine are the first line of therapy. In cases where cholestyramine has failed, rifampicin and antihistamines may be beneficial. Opiate antagonists hold great potential if opioid withdrawal-like syndromes can be avoided. Ursodeoxycholic acid and methotrexate have an advantage in not only relieving pruritus but also potentially retarding disease progression in PBC and PSC, respectively, although this remains to be proved. Other agents such as EPO and SAMe remain experimental and require further study to clarify their effectiveness before they can be recommended.

Subhypnotic doses of propofol relieve pruritus associated with liver disease

BACKGROUND

Pruritus is a severe and troublesome symptom in patients with cholestasis and is often difficult to treat. Propofol was recently shown to be efficient in relieving pruritus secondary to spinal morphine administration. The efficacy of propofol was therefore investigated in patients with pruritus associated with liver disease.

METHODS

In a prospective, randomized, double-blind, crossover, placebo-controlled study, 10 patients received 2 doses of propofol (1.5 mL = 15 mg) and 2 doses of placebo (1.5 mL of Intralipid, Kabi-Pharm., Helsinki, Finland) during a 4-day study period. Pruritus was assessed by a verbal rating score from 0 (no pruritus) to 10 (most severe pruritus imaginable). Treatment success was defined as a decrease of pruritus of at least 4 points in the verbal rating score.

RESULTS

Treatment success was achieved in 85% of the patients receiving propofol and in 10% of those receiving Intralipid (P < 0.01). Discomfort on injection (15%) and slight dizziness (10%) were observed with propofol treatment.

CONCLUSIONS

This study shows that subhypnotic doses of propofol are effective for the short-term symptomatic relief of pruritus associated with liver disease. At the dose used, side effects were rare and minor.

Plasma from patients with the pruritus of cholestasis induces opioid receptor-mediated scratching in monkeys

The medullary dorsal horn is a site of action of opiates in producing facial scratching. Extracts of plasma (0.4 microliter) from 4 patients with the pruritus of cholestasis induced facial scratching when microinjected into the medullary dorsal horn of monkeys. This extract-induced scratching could be abolished or prevented by administering the opioid receptor antagonist, naloxone. Neither saline nor an extract of plasma from a nonpruritic cholestatic patient induced scratching when similarly administered. We infer that plasma of patients with the pruritus of cholestasis contains a factor which induces pruritus by a central opioid receptor-mediated mechanism.