Summary

Drug induced cholestatic liver disease is a subtype of liver injury that is characterized by predominant elevations of alkaline phosphatase and bilirubin secondary to the administration of a hepatotoxic agent. It can manifest itself as a cholestatic hepatitis or as bland cholestasis, depending upon the causative agent and the mechanism of injury. Drugs that typically cause cholestasis with hepatitis include psychotropic agents, antibiotics and nonsteroidal antiinflammatory drugs (NSAIDs). The mechanism is immunoallergic and results from hypersensitivity. Pure cholestasis without hepatitis is observed most frequently with contraceptive and 17α-alkylated androgenic steroids and the mechanism most likely involves interference with hepatocyte canalicular efflux systems for bile salts, organic anions and phospholipids. The rate-limiting step in bile formation is considered to be the bile salt export pump (BSEP) mediated translocation of bile salts across the canalicular hepatocyte membrane. Inhibition of BSEP function by metabolites of cyclosporine A, troglitazone, bosentan, rifampicin and sex steroids is an important cause of drug induced cholestasis. Appropriate screening systems for inhibition of BSEP by drug metabolites have been established in membrane vesicles from Sf9 insect cells overexpressing the BSEP protein. A newly recognized mechanism of drug interactions that could cause cholestasis involves the activation of nuclear receptor signaling cascades which affect the transcription of hepatocyte transporter genes critical for bile formation. The multiple factors that regulate transcription of, for example, the BSEP, multidrug resistance protein 2 (MRP2) and multidrug resistance gene product 3 (MDR3) genes are likely targets for untoward effects of xenobiotics on hepatocyte transport function and disposal of toxic metabolites from the liver.

Introduction

The liver plays a predominant role in drug biotransformation and disposition from the body. In view of its barrier function between the gastrointestinal tract and systemic blood, it is constantly exposed to ingested xenobiotics entering the portal circulation. Drug-induced liver injury accounts for up to 7% of all reports of adverse drug effects voluntarily reported to pharmacovigilance registries. Drugs cause direct damage to hepatocytes, bile ducts or vascular structures or may interfere with bile flow. The phenotypes commonly encountered thus include hepatitis, cholestasis, steatosis, cirrhosis, vascular and neoplastic lesions and even fulminant hepatic failure.

Almost every drug has the potential to cause hepatic injury, be it through direct toxicity of the agent or through an idiosyncratic response of the individual. The susceptibility of the liver to injury by drugs is influenced by various factors such as age, sex, pregnancy, comedication, renal function and genetic factors. The latter variable is exemplified by slow metabolizers of debrisoquine, who exhibit a gene polymorphism in the cytochrome P450 2D6 gene and are more susceptible than fast metabolizers to perhexiline maleate toxicity. Other genetically determined enzyme deficiencies that predispose to drug toxicity have been described for cytochrome P450 2C9 (phenytoin toxicity), N-acetyltransferase 2 (sulfonamides, dihydralazine), epoxide hydrolase (phenytoin, halothane), glutathione synthetase (paracetamol) and glutathione S transferase type T (tacrin).^1,2

Epidemiology and Taxonomy

The importance of drugs as hepatotoxins lies not in the overall number of cases, which is relatively small, but in the severity of some reactions and in their potential reversibility provided the drug etiology is promptly recognized. Whereas transient elevations in liver function tests are frequent with many drugs, the incidence of severe liver injury is about 1:100,000 for the most common causative agents including NSAIDs, antibiotics, methyldopa, newer antihypertensive agents and H₂-receptor blockers, >10:100,000 for amoxicillin-clavulanic acid, 14:100,000 for erythromycin esters, and ∼1:100 for chlorpromazine and isoniazid.^3,4 According to a consensus conference of the Council for International Organizations of Medical Sciences (CIOMS), drug induced hepatotoxicity can be divided into the three categories: cholestatic, hepatocellular or mixed type injury, depending upon serum biochemistry.⁵ Cholestasis with hepatitis is seen with many drugs, notably chlorpromazine, psychotropic agents, erythromycins, clavulanic acid and NSAIDs. Pure cholestasis without hepatitis is observed most frequently with estrogens, oral contraceptive steroids and 17α-alkylated androgenic steroids, and less frequently with cyclosporine A, tamoxifen, griseofulvin, glibenclamide and others. Steroid jaundice caused by methyltestosterone and other C17-alkylated anabolic steroids is dose-related but is also dependent upon the individual susceptibility of the recipient. Whereas hepatic dysfunction is seen in most recipients of steroids, jaundice is seen in only few. A minor degree of hepatic dysfunction in women taking oral contraceptives which contain C-17 ethinyl estrogen and progesterone derivatives is relatively frequent. Women with a personal or family history of cholestatic jaundice of pregnancy are particularly prone to develop jaundice when taking oral contraceptives. In addition to the “cholestatic hepatitis” of the chlorpromazine type and “bland cholestasis” caused by anabolic and contraceptive steroids, a third category of cholestasis that results from injury to bile ducts should be defined. This “cholangiodestructive cholestasis” has been observed following exposure to rapeseed oil contaminated with aniline,⁶ paraquat,⁷ α-naphthyl-isothiocyanate⁸ and intraarterial pump infusions of floxuridine,⁹ the latter leading to vascular injury.

Although the prognosis of drug-induced cholestasis is generally good with reversibility of symptoms, a chronic cholestatic lesion resembling primary biliary cirrhosis may ensue.¹⁰ The worst case involves development of a ductopenic or vanishing bile duct syndrome associated with chlorpromazine and phenothiazines, tricyclic antidepressants, flucloxacillin, thiabendazole, tolbutamide, carbamazepine and organic arsenicals.¹¹ The injury to bile ducts caused by floxuridine may progress to biliary sclerosis.^9,12 Other complications of typically cholestatic drugs include the onset of peliosis hepatis in individuals taking contraceptive or anabolic steroids,^13-15 tamoxifen¹⁶ or azathioprine,¹⁷ as well as tumorigenesis.¹⁸

From a histologic viewpoint, drug-induced cholestasis can be divided into three categories: hepatocanalicular, canalicular or mixed type injury, depending also upon serum biochemistry. Hepatocanalicular cholestasis is associated with 3- to 10 fold increases of alkaline phosphatase and high serum cholesterol, and is seen in conjunction with phenothiazines and erythromycin estolate. In canalicular cholestasis, typically caused by contraceptive and anabolic steroids, alkaline phosphatase levels are only mildly elevated (up to 3 fold the upper limit of normal) and cholesterol levels are normal or elevated. Mixed-type cholestasis is seen with phenylbutazone, para-aminosalicylic acid and sulfonamides.

Mechanisms of Cholestasis

The following basic mechanisms can be held responsible for the development of drug- or toxin-induced cholestasis (Table 1). The first involves the formation of reactive metabolites^19-22 leading to two types of hepatitis:

Table 1

Prototypic cholestatic hepatotoxins and mechanism of injury.

1. toxic hepatitis, typically occurring after overdoses of a given drug (e.g., paracetamol) and,
2. immunoallergic hepatitis, in which an adverse immune response that is directed against the liver is triggered.

This latter form of hepatitis is an idiosyncratic reaction resulting from hypersensitivity and may be associated with the presence of serum autoantibodies (ANA in the case of nitrofurantoin, methyldopa, chlorpromazine, diclofenac, sulfonamides and nimesulide; AMA against the E6 subunit following iproniazide; antibodies against the E2 subunit of the pyruvate dehydrogenase complex following halothane).^22-25 The second mechanism of cholestasis involves direct injury to bile ducts, typically seen in conjunction with α-naphthyl-isothiocyanate, aniline-contaminated rapeseed oil, paraquat, 5-floxuridine and sporidesmin. The third and possibly the most important mechanism of cholestasis involves the selective interference of a drug with a bile excretory mechanism. Many cholestatic drugs are substrates for the transport proteins localized at the basolateral and canalicular hepatocyte membrane, the latter class generally belonging to the superfamily of ATP-binding cassette transporters.²⁶ A variation in transporter structure or function may render an individual uniquely susceptible to drug-mediated impairment of bile formation. In analogy to variations in cytochrome P450 function that predispose to altered drug metabolism, variations in transporter function represent a major field of research within the rapidly expanding field of pharmacogenomics.²⁷ Examples for sequence variants of hepatocyte canalicular efflux systems include the mutations of the MDR3 phospholipid export pump that predispose to intrahepatic cholestasis of pregnancy as a result of high circulating levels of progesterone metabolites,^28,29 as well as the recently described heterozygous mutations of the bile salt export pump in an adolescent patient suffering from recurrent intrahepatic cholestasis, possibly triggered by the intake of certain NSAIDs.³⁰

Interference with Bile Excretory Mechanisms

A simplified term to characterize this form of “bland” cholestasis could be “steroid jaundice”, since the most important causative agents are the C17-alkylated and the contraceptive steroids. Steroids that possess an alkyl or ethinyl group on carbon atom 17 can lead to hepatic dysfunction in almost all recipients at high doses. However, at the doses normally implemented the overall incidence is low. The duration of intake that precedes the onset of cholestasis is usually 1-6 months. The development of a prolonged cholestatic syndrome that resembles PBC has been reported.⁴⁴

Contraceptive steroid associated cholestasis exhibits similarities with intrahepatic cholestasis of pregnancy, in which the plasma levels of steroid sulfates, in particular sulfated progesterone metabolites, are markedly elevated.⁴⁵ Intrahepatic cholestasis of pregnancy has even been postulated to result from a selective biliary excretory defect for sulfated steroids.⁴⁶ Interestingly, treatment with ursodeoxy cholic acid (UDCA) reduces plasma concentrations of sulfated steroid metabolites.⁴⁷

The rate-limiting step for bile formation in man is the efflux of bile salts across the hepatocyte canalicular membrane via the bile salt export pump or Bsep.⁴⁸ This protein, which has been isolated and functionally characterized in rat and mouse liver,^49-51 can be expressed at high levels in Sf9 insect cells following baculovirus-mediated gene transfer. By isolating plasma membrane vesicles from Bsep-expressing insect cells, Bsep transport function can be studied directly. In this assay, it was found that cyclosporine A, rifamycin SV, rifampicin, glibenclamide and the endothelin antagonist bosentan cis-inhibited Bsep-mediated [³H]taurocholate transport, providing a potential mechanism for intrahepatic cholestasis caused by these agents (Table 2).^27,52 Moreover, the thiazolidinedione insulin sensitizer drug troglitazone, which was withdrawn from the market in March 2000 due to its considerable hepatotoxic potential,^53-55 was shown to competitively inhibit rat Bsep with Ki values of 1.3 μM for troglitazone and 0.23 μM for troglitazone sulfate.⁵⁶ In one study, the substrate specificity of Bsep was shown to extend not only to bile salts but also to vinblastine, calcein-acetoxymethyl ester and the linear hexapeptide ditekiren.⁵⁰ Interaction of these compounds with the canalicular efflux of bile salts is an important mechanism of drug-induced cholestasis.

Table 2

Inhibitors of hepatocellular bile salt efflux: comparison of inhibitory constants in hepatocyte canalicular plasma membrane vesicles and Bsep-overexpressing Sf9 insect cell membrane vesicles.

Estradiol-17β-D-glucuronide (E217G) has also been found to inhibit Bsep function in vesicles from transfected Sf9 cells, but only in double transfectants that also expressed the canalicular conjugate export pump Mrp2.²⁷ This suggests that E₂17G first needs to be exported into the canalicular lumen, from where it exerts a trans-inhibitory effect on Bsep, a mechanism of inhibition that has also been postulated for lithocholate. This also explains why E₂17G is not cholestatic in GY/TR- rats that lack Mrp2 expression.⁵⁷ In contrast to E₂17G induced trans-inhibition of Bsep, the mechanism of ethinyl estradiol (EE) induced cholestasis is also a reduction of ATP-dependent canalicular taurocholate transport, however with kinetic parameters that suggest a reduction in the number of ATP-dependent bile salt carriers at the canalicular membrane.⁵⁸ Accordingly, in rats treated with EE, Bsep protein levels were decreased to 53% and Mrp2 protein levels to 20% of controls.⁵⁹

The nonsteroidal anti-inflammatory agent sulindac, an established hepatotoxin,⁶⁰ may also cause cholestasis by interference with the canalicular excretion of bile salts. Sulindac has been shown to follow the cholehepatic shunt pathway and induce choleresis.⁶¹ However, when coinfused with taurocholate in the isolated perfused rat liver, sulindac causes cholestasis by reducing taurocholate secretion. Sulindac appears to be secreted into the bile canaliculus in unconjugated form via a canalicular bile salt export system and is passively absorbed by the bile duct epithelium, thereby inducing a bicarbonate-rich choleresis. Due to continuous cycling within the cholehepatic shunt pathway, high local concentrations of sulindac could be reached within the hepatocyte that cause cholestasis by inhibition of canalicular bile salt efflux.

An important form of intrahepatic cholestasis is the cholestasis of sepsis, which is caused by the effect of endotoxin on hepatocellular bile formation. In experimental sepsis secondary to lipopolysaccharide (LPS) administration, ATP-dependent uptake of 5 μM taurocholate in canalicular plasma membrane vesicles was reduced to 53% of controls without an apparent change in Km, suggesting a decrease in the number of Bsep molecules in the canalicular membrane.⁶² A reduction of Bsep protein levels to 52% of controls following LPS administration was confirmed by western blot analyses.⁵⁹ The expression of the canalicular organic anion transporter Mrp2 was decreased even more profoundly, amounting to 11% of controls in the LPS model.⁵⁹ LPS was shown to induce an early and selective but reversible retrieval of Mrp2 from the canalicular membrane,⁶³ whereas phalloidin induced an unselective and irreversible loss of Mrp2 and other proteins from the canalicular membrane.⁶⁴

Selective interference with the sinusoidal uptake of substances destined for biliary secretion such as bilirubin and bromosulphophthalein has been shown for the tuberculostatic agents rifamycin SV and rifampicin.⁶⁵ Both are mainly eliminated by hepatic uptake, metabolism and excretion into bile. Rifampicin increases serum bile salt concentrations in 72% of patients after the first dose,⁶⁶ suggesting acute interference with sinusoidal uptake of bile salts. The major bile salt uptake system of rat liver is the Na⁺-taurocholate cotransporting polypeptide or Ntcp, whereas Na⁺-independent uptake of bile salts is mediated by several organic anion transporting polypeptides including Oatp1 and Oatp2.⁴⁸ When selectively expressed in Xenopus laevis oocytes by injection of cRNA, rifampicin potently inhibited Oatp2 mediated taurocholate uptake, but did not interfere with Oatp1 mediated taurocholate uptake. Both Oatp1 and Oatp2 were inhibited by 10 μmol/l rifamycin SV, whereas significantly higher concentrations of rifamycin SV and rifampicin were required to inhibit Ntcp.⁶⁷ For the human liver OATPs, it was shown that 10 μmol/l rifampicin inhibited OATP8 mediated bromosulphophthalein transport by 50%, whereas inhibition of OATP-A, OATP-B and OATP-C was below 15%. In contrast, all human OATPs were inhibited by more than 50% in the presence of 10 μmol/l rifamycin SV.⁶⁸ Inhibition of OATPs can partly explain the known effects of rifamycin SV and rifampicin on hepatic organic anion elimination.

Conclusions

In summary, drug-induced cholestatic liver injury can result from direct damage to the hepatic parenchyma by immunoallergic or toxic mechanisms or from impaired transmembrane transport of cholephilic compounds destined for biliary secretion. The rate-limiting step in bile formation is the canalicular excretion of bile salts via the bile salt export pump, which thus represents an especially vulnerable target for drug or toxin mediated injury. The earliest clinical parameter in these patients, which precedes the onset of symptomatic cholestasis, is a rise in serum bile salts. It is likely that individual susceptibility to drug- and toxin-induced cholestasis is conferred by as yet unknown polymorphisms in hepatic transporter genes, that could affect the regulation or secondary structure of the corresponding protein.

References

1.

Edwards IR, Aronson JK. Adverse drug reactions: definitions, diagnosis, and management. Lancet. 2000;356:1255–9. [PubMed: 11072960]

2.

Meyer UA. Pharmacogenetics and adverse drug reactions. Lancet. 2000;356:1667–71. [PubMed: 11089838]

3.

Perez GutthannS, Garcia RodriguezLA. The increased risk of hospitalizations for acute liver injury in a population with exposure to multiple drugs. Epidemiology. 1993;4:496–501. [PubMed: 8268277]

4.

Garcia RodriguezLA, Ruigomez A, Jick H. A review of epidemiologic research on drug-induced acute liver injury using the general practice research data base in the United Kingdom. Pharmacotherapy. 1997;17:721–8. [PubMed: 9250549]

5.

Benichou C. Criteria of drug-induced liver disorders. Report of an international consensus meeting. J Hepatol. 1990;11:272–6. [PubMed: 2254635]

6.

Solis HerruzoJA, Castellano G, Colina F. et al. Hepatic injury in the toxic epidemic syndrome caused by ingestion of adulterated cooking oil (Spain, 1981). Hepatology. 1984;4:131–9. [PubMed: 6693064]

7.

Mullick FG, Ishak KG, Mahabir R. et al. Hepatic injury associated with paraquat toxicity in humans. Liver. 1981;1:209–21. [PubMed: 7348757]

8.

Plaa GL. The Snider Address. A four-decade adventure in experimental liver injury. Drug Metab Rev. 1997;29:1–37. [PubMed: 9187509]

9.

Ludwig J, Kim CH, Wiesner RH. et al. Floxuridine-induced sclerosing cholangitis: an ischemic cholangiopathy? Hepatology. 1989;9:215–8. [PubMed: 2521475]

10.

Zimmerman HJ, Lewis JH. Drug-induced cholestasis. Med Toxicol. 1987;2:112–60. [PubMed: 3553833]

11.

Desmet VJ. Vanishing bile duct syndrome in drug-induced liver disease. J Hepatol. 1997;26:131–5. [PubMed: 9138126]

12.

Hohn DC, Rayner AA, Economou JS. et al. Toxicities and complications of implanted pump hepatic arterial and intravenous floxuridine infusion. Cancer. 1986;57:465–70. [PubMed: 2935242]

13.

Bagheri SA, Boyer JL. Peliosis hepatis associated with androgenic-anabolic steroid therapy. A severe form of hepatic injury. Ann Intern Med. 1974;81:610–8. [PubMed: 4423214]

14.

Winkler K, Poulsen H. Liver disease with periportal sinusoidal dilatation. A possible complication to contraceptive steroids. Scand J Gastroenterol. 1975;10:699–704. [PubMed: 1188303]

15.

Schonberg LA. Peliosis hepatis and oral contraceptives. A case report. J Reprod Med. 1982;27:753–6. [PubMed: 7161757]

16.

Loomus GN, Aneja P, Bota RA. A case of peliosis hepatis in association with tamoxifen therapy. Am J Clin Pathol. 1983;80:881–3. [PubMed: 6637896]

17.

Degott C, Rueff B, Kreis H. et al. Peliosis hepatis in recipients of renal transplants. Gut. 1978;19:748–53. [PMC free article: PMC1412137] [PubMed: 355072]

18.

Zimmerman HJ. Drug-induced liver diseaseIn: Schiff ER, Sorrell MF, Maddrey WC, eds.Schiff's Diseases of the LiverPhiladelphia: Lippincott-Raven,1999973–1064.

19.

Larrey D. Drug-induced liver diseases. J Hepatol. 2000;32(Suppl 1):77–88. [PubMed: 10728796]

20.

Farrell GC. Drug-induced liver disease. London: Churchill Livingstone. 1994

21.

Pessayre D, Larrey D, Biour M. Drug-induced liver injuryIn: Bircher J, Benhamou JP, McIntyre N, Rizzetto M, Rodés J, eds.Oxford Textbook of Clinical HepatologyOxford: Oxford University Press,19991261–1315.

22.

Dansette PM, Bonierbale E, Minoletti C. et al. Drug-induced immunotoxicity. Eur J Drug Metab Pharmacokinet. 1998;23:443–51. [PubMed: 10323325]

23.

Homberg JC, Abuaf N, Bernard O. et al. Chronic active hepatitis associated with antiliver/kidney microsome antibody type 1: a second type of “autoimmune” hepatitis. Hepatology. 1987;7:1333–9. [PubMed: 3679093]

24.

Bourdi M, Larrey D, Nataf J. et al. Anti-liver endoplasmic reticulum autoantibodies are directed against human cytochrome P-450IA2. A specific marker of dihydralazine-induced hepatitis. J Clin Invest. 1990;85:1967–73. [PMC free article: PMC296665] [PubMed: 2347920]

25.

Beaune P, Dansette PM, Mansuy D. et al. Human anti-endoplasmic reticulum autoantibodies appearing in a drug-induced hepatitis are directed against a human liver cytochrome P-450 that hydroxylates the drug. Proc Natl Acad Sci U S A. 1987;84:551–5. [PMC free article: PMC304247] [PubMed: 3540968]

26.

Trauner M, Meier PJ, Boyer JL. Molecular pathogenesis of cholestasis. N Engl J Med. 1998;339:1217–1227. [PubMed: 9780343]

27.

Stieger B, Fattinger K, Madon J. et al. Drug- and estrogen-induced cholestasis through inhibition of the hepatocellular bile salt export pump (Bsep) of rat liver. Gastroenterology. 2000;118:422–430. [PubMed: 10648470]

28.

Jacquemin E, Cresteil D, Manouvrier S. et al. Heterozygous non-sense mutation of the MDR3 gene in familial intrahepatic cholestasis of pregnancy [letter] Lancet. 1999;353:210–1. [PubMed: 9923886]

29.

Lammert F, Marschall HU, Glantz A. et al. Intrahepatic cholestasis of pregnancy: molecular pathogenesis, diagnosis and management. J Hepatol. 2000;33:1012–1021. [PubMed: 11131439]

30.

Kullak-Ublick GA, Kerb R, Müllhaupt B. et al. A novel R432T mutation in the bile salt export pump gene (BSEP; ABCB11) is associated with recurrent intrahepatic cholestasis in an adolescent patient [abstract] Hepatology. 2001;34:216A.

31.

Boyer JL. Mechanisms of chlorpromazine cholestasis: hypersensitivity or toxic metabolite? Gastroenterology. 1978;74:1331–3. [PubMed: 648827]

32.

Elias E, Boyer JL. Chlorpromazine and its metabolites alter polymerization and gelation of actin. Science. 1979;206:1404–6. [PubMed: 574316]

33.

Ros E, Small DM, Carey MC. Effects of chlorpromazine hydrochloride on bile salt synthesis, bile formation and biliary lipid secretion in the rhesus monkey: a model for chlorpromazine-induced cholestasis. Eur J Clin Invest. 1979;9:29–41. [PubMed: 110598]

34.

Schachter D. Fluidity and function of hepatocyte plasma membranes. Hepatology. 1984;4:140–51. [PubMed: 6319260]

35.

Kohn NN, Myerson RM. Xanthomatous biliary cirrhosis following chlorpromazine. Am J Med. 1961;31:665–667. [PubMed: 14457847]

36.

Lewis JH, Tice HL, Zimmerman HJ. Budd-Chiari syndrome associated with oral contraceptive steroids. Review of treatment of 47 cases. Dig Dis Sci. 1983;28:673–83. [PubMed: 6872799]

37.

Degott C, Feldmann G, Larrey D. et al. Drug-induced prolonged cholestasis in adults: a histological semiquantitative study demonstrating progressive ductopenia. Hepatology. 1992;15:244–51. [PubMed: 1735527]

38.

Watson RG, Olomu A, Clements D. et al. A proposed mechanism for chlorpromazine jaundice-defective hepatic sulphoxidation combined with rapid hydroxylation. J Hepatol. 1988;7:72–8. [PubMed: 3183354]

39.

Bach N, Thung SN, Schaffner F. et al. Exaggerated cholestasis and hepatic fibrosis following simultaneous administration of chlorpromazine and sodium valproate. Dig Dis Sci. 1989;34:1303–7. [PubMed: 2502367]

40.

Reddy KR, Schiff ER. Hepatotoxicity of antimicrobial, antifungal and antiparasitic agents. Gastroenterol Clin N Am. 1995;24:923–936. [PubMed: 8749905]

41.

Hebbard GS, Smith KG, Gibson PR. et al. Augmentin-induced jaundice with a fatal outcome. Med J Aust. 1992;156:285–6. [PubMed: 1738330]

42.

Eckstein RP, Dowsett JF, Lunzer MR. Flucloxacillin induced liver disease: histopathological findings at biopsy and autopsy. Pathology. 1993;25:223–8. [PubMed: 8265236]

43.

Munoz SJ, Martinez HernandezA, Maddrey WC. Intrahepatic cholestasis and phospholipidosis associated with the use of trimethoprim-sulfamethoxazole. Hepatology. 1990;12:342–7. [PubMed: 2167870]

44.

Glober GA, Wilkerson JA. Biliary cirrhosis following the administration of methyltestosterone. Jama. 1968;204:170–3. [PubMed: 5694548]

45.

Sjovall J, Sjovall K. Steroid sulphates in plasma from pregnant women with pruritus and elevated plasma bile acid levels. Ann Clin Res. 1970;2:321–37. [PubMed: 5493462]

46.

Reyes H, Sjövall J. Bile acids and progesterone metabolites in intrahepatic cholestasis of pregnancy. Ann Med. 2000;32:94–106. [PubMed: 10766400]

47.

Meng LJ, Reyes H, Axelson M. et al. Progesterone metabolites and bile acids in serum of patients with intrahepatic cholestasis of pregnancy: effect of ursodeoxycholic acid therapy. Hepatology. 1997;26:1573–9. [PubMed: 9398000]

48.

Kullak-Ublick GA, Stieger B, Hagenbuch B. et al. Hepatic transport of bile salts. Semin Liver Dis. 2000;20:273–292. [PubMed: 11076396]

49.

Gerloff T, Stieger B, Hagenbuch B. et al. The sister of P-glycoprotein represents the canalicular bile salt export pump of mammalian liver. J Biol Chem. 1998;273:10046–50. [PubMed: 9545351]

50.

Lecureur V, Sun D, Hargrove P. et al. Cloning and expression of murine sister of P-glycoprotein reveals a more discriminating transporter than MDR1/P-glycoprotein. Mol Pharmacol. 2000;57:24–35. [PubMed: 10617675]

51.

Green RM, Hoda F, Ward KL. Molecular cloning and characterization of the murine bile salt export pump. Gene. 2000;241:117–123. [PubMed: 10607905]

52.

Fattinger K, Funk C, Pantze M. et al. The endothelin antagonist bosentan inhibits the canalicular bile salt export pump: a potential mechanism for hepatic adverse reactions. Clin Pharmacol Ther. 2001;69:223–31. [PubMed: 11309550]

53.

Gitlin N, Julie NL, Spurr CL. et al. Two cases of severe clinical and histologic hepatotoxicity associated with troglitazone. Ann Intern Med. 1998;129:36–8. [PubMed: 9652997]

54.

Neuschwander TetriBA, Isley WL, Oki JC. et al. Troglitazone-induced hepatic failure leading to liver transplantation. A case report. Ann Intern Med. 1998;129:38–41. [PubMed: 9652998]

55.

Herrine SK, Choudhary C. Severe hepatotoxicity associated with troglitazone. Ann Intern Med. 1999;130:163–4. [PubMed: 10068372]

56.

Funk C, Ponelle C, Scheuermann G. et al. Cholestatic potential of troglitazone as a possible factor contributing to troglitazone-induced hepatotoxicity: in vivo and in vitro interaction at the canalicular bile salt export pump (Bsep) in the rat. Mol Pharmacol. 2001;59:627–35. [PubMed: 11179459]

57.

Sano N, Takikawa H, Yamanaka M. Estradiol-17 beta-glucuronide-induced cholestasis. Effects of ursodeoxycholate-3-O-glucuronide and 3,7-disulfate. J Hepatol. 1993;17:241–6. [PubMed: 8445238]

58.

Bossard R, Stieger B, O'Neill B. et al. Ethinylestradiol treatment induces multiple canalicular membrane transport alterations in rat liver. J Clin Invest. 1993;91:2714–2720. [PMC free article: PMC443336] [PubMed: 8514879]

59.

Lee JM, Trauner M, Soroka CJ. et al. Expression of the bile salt export pump is maintained after chronic cholestasis in the rat. Gastroenterology. 2000;118:163–172. [PubMed: 10611165]

60.

Rodriguez LAG, Williams R, Derby LE. et al. Acute liver injury associated with nonsteroidal anti-inflammatory drugs and the role of risk factors. Arch Intern Med. 1994;154:311–316. [PubMed: 8297198]

61.

Bolder U, Trang NV, Hagey LR. et al. Sulindac is excreted into bile by a canalicular bile salt pump and undergoes a cholehepatic circulation in rats. Gastroenterology. 1999;117:962–71. [PubMed: 10500080]

62.

Bolder U, Ton-Nu H-T, Schteingart CD. et al. Hepatocyte transport of bile acids and organic anions in endotoxemic rats: impaired uptake and secretion. Gastroenterology. 1997;112:214–225. [PubMed: 8978362]

63.

Kubitz R, Wettstein M, Warskulat U. et al. Regulation of the multidrug resistance protein 2 in the rat liver by lipopolysaccharide and dexamethasone. Gastroenterology. 1999;116:401–10. [PubMed: 9922322]

64.

Rost D, Kartenbeck J, Keppler D. Changes in the localization of the rat canalicular conjugate export pump Mrp2 in phalloidin-induced cholestasis. Hepatology. 1999;29:814–21. [PubMed: 10051484]

65.

Acocella G, Nicolis FB, Tenconi LT. The effect of an intravenous infusion of rifamycin SV on the excretion of bilirubin, bromsulphalein, and indocyanine green in man. Gastroenterology. 1965;49:521–5. [PubMed: 5322057]

66.

Galeazzi R, Lorenzini I, Orlandi F. Rifampicin-induced elevation of serum bile acids in man. Dig Dis Sci. 1980;25:108–12. [PubMed: 7353456]

67.

Fattinger K, Cattori V, Hagenbuch B. et al. Rifamycin SV and rifampicin exhibit differential inhibition of the hepatic rat organic anion transporting polypeptides, Oatp1 and Oatp2. Hepatology. 2000;32:82–86. [PubMed: 10869292]

68.

Vavricka SR, van MontfoortJ, Ha HR. et al. Interactions of rifamycin SV and rifampicin with OATP-C, OATP8, OATP-B and OATP-A of human liver. Hepatology. 2002;36:164–72. [PubMed: 12085361]

69.

Geick A, Eichelbaum M, Burk O. Nuclear receptor response elements mediate induction of intestinal MDR1 by rifampin. J Biol Chem. 2001;276:14581–7. [PubMed: 11297522]

70.

Greiner B, Eichelbaum M, Fritz P. et al. The role of intestinal P-glycoprotein in the interaction of digoxin and rifampin. J Clin Invest. 1999;104:147–53. [PMC free article: PMC408477] [PubMed: 10411543]

71.

Dürr D, Stieger B, Kullak-Ublick GA. et al. St John's Wort induces intestinal P-glycoprotein/ MDR1 and intestinal and hepatic CYP3A4. Clin Pharmacol Ther. 2000;68:598–604. [PubMed: 11180019]

72.

Hagenbuch N, Reichel C, Stieger B. et al. Effect of phenobarbital on the expression of bile salt and organic anion transporters of rat liver. J Hepatol. 2001;34:881–887. [PubMed: 11451172]

73.

Staudinger JL, Goodwin B, Jones SA. et al. The nuclear receptor PXR is a lithocholic acid sensor that protects against liver toxicity. Proc Natl Acad Sci U S A. 2001;98:3369–3374. [PMC free article: PMC30660] [PubMed: 11248085]

74.

Jones SA, Moore LB, Shenk JL. et al. The pregnane X receptor: a promiscuous xenobiotic receptor that has diverged during evolution. Mol Endocrinol. 2000;14:27–39. [PubMed: 10628745]

75.

Moore LB, Goodwin B, Jones SA. et al. St. John's wort induces hepatic drug metabolism through activation of the pregnane X receptor. Proc Natl Acad Sci U S A 2000. 97:7500–2. [PMC free article: PMC16574] [PubMed: 10852961]

76.

Kullak-Ublick GA, Jung D, Hagenbuch B. et al. Organic anion transporting polypeptides, cholestasis and nuclear receptors. Hepatology. 2002;35:732–3. [PubMed: 11870396]

77.

Denson LA, Auld KL, Schiek DS. et al. Interleukin-1beta suppresses retinoid transactivation of two hepatic transporter genes involved in bile formation. J Biol Chem. 2000;275:8835–43. [PubMed: 10722729]

78.

Wang B, Cai SR, Gao C. et al. Lipopolysaccharide results in a marked decrease in hepatocyte nuclear factor 4α in rat liver. Hepatology. 2001;34:979–989. [PubMed: 11679969]

79.

Karpen SJ, Sun A-Q, Kudish B. et al. Multiple factors regulate the rat liver basolateral sodium-dependent bile acid cotransporter gene promoter. J Biol Chem. 1996;271:15211–15221. [PubMed: 8662994]

80.

Tanaka T, Uchiumi T, Hinoshita E. et al. The human multidrug resistance protein 2 gene: functional characterization of the 5'-flanking region and expression in hepatic cells. Hepatology. 1999;30:1507–1512. [PubMed: 10573531]

81.

Stockel B, Konig J, Nies AT. et al. Characterization of the 5'-flanking region of the human multidrug resistance protein 2 (MRP2) gene and its regulation in comparison with the multidrug resistance protein 3 (MRP3) gene. Eur J Biochem. 2000;267:1347–58. [PubMed: 10691972]

82.

Jung D, Hagenbuch B, Gresh L. et al. Characterization of the human OATP-C (SLC21A6) gene promoter and regulation of liver-specific OATP genes by hepatocyte nuclear factor 1α J Biol Chem. 2001;276:37206–37214. [PubMed: 11483603]

83.

Makishima M, Okamoto AY, Repa JJ. et al. Identification of a nuclear receptor for bile acids. Science. 1999;284:1362–1365. [PubMed: 10334992]

84.

Parks DJ, Blanchard SG, Bledsoe RK. et al. Bile acids: natural ligands for an orphan nuclear receptor. Science. 1999;284:1365–8. [PubMed: 10334993]

85.

Ananthanarayanan M, Balasubramanian N, Makishima M. et al. Human bile salt export pump (BSEP) promoter is transactivated by the farnesoid X receptor/bile acid receptor (FXR/BAR). J Biol Chem. 2001;276:28857–28865. [PubMed: 11387316]

86.

Schuetz EG, Strom S, Yasuda K. et al. Disrupted bile acid homeostasis reveals an unexpected interaction among nuclear hormone receptors, transporters, and cytochrome P450. J Biol Chem. 2001;276:39411–39418. [PubMed: 11509573]

87.

Jung D, Podvinec M, Meyer UA. et al. Human organic anion transporting polypeptide 8 promoter is transactivated by the farnesoid X receptor/bile acid receptor. Gastroenterology. 2002;122:1954–66. [PubMed: 12055601]

88.

Denson LA, Sturm E, Echevarria W. et al. The orphan nuclear receptor, shp, mediates bile acid-induced inhibition of the rat bile acid transporter, ntcp. Gastroenterology. 2001;121:140–147. [PubMed: 11438503]