What is the treatment for drug-induced liver disease?
The most important treatment for drug-induced liver disease is stopping the drug that is causing the liver disease. In most patients, signs and symptoms of liver disease will resolve and blood tests will become normal and there will be no long-term liver damage. There are exceptions, however. For example, Tylenol overdoses are treated with oral N-acetylcysteine to prevent severe liver necrosis and failure. Liver transplantation may be necessary for some patients with acute liver failure. Some drugs also can cause irreversible liver damage and cirrhosis.
What are some important examples of drug-induced liver disease?
An overdose of acetaminophen can damage the liver. The probability of damage as well as the severity of the damage depends on the dose of acetaminophen ingested; the higher the dose, the more likely it is that there will be damage, and the more likely it is that the damage will be severe. (The reaction to acetaminophen is dose-dependent and predictable; it is not idiosyncratic — peculiar to the individual.) The liver injury from an overdose of acetaminophen is a serious matter since the damage can be severe and result in liver failure and death. In fact, acetaminophen overdose is the leading cause of acute (rapid onset) liver failure in the U.S. and the United Kingdom.
For the average healthy adult, the recommended maximum dose of acetaminophen during a 24-hour period is 4 grams (4,000 mg) or eight extra-strength tablets. (Each extra-strength tablet contains 500 mg, while each regular strength tablet contains 325 mg.) Among children, the dose of acetaminophen is determined on the basis of each child’s weight and age, explicitly stated in the package insert. If these guidelines for adults and children are followed, acetaminophen is safe and carries essentially no risk of liver injury. A person who drinks more than two alcoholic beverages per day, however, should not take more than 2 grams (2,000 mg) of acetaminophen over 24 hours, as discussed below, since alcohol makes the liver susceptible to damage from lower doses of acetaminophen.
A single dose of 7 to 10 grams (7,000 mg-10,000 mg) of acetaminophen (14 to 20 extra-strength tablets), twice the recommended dose, can cause liver injury in the average healthy adult. Among children, a single dose of 140 mg/kg (body weight) of acetaminophen can result in liver injury. Nevertheless, 3 to 4 grams (3,000 mg-4,000 mg) taken in a single dose or 4 to 6 grams (4,000 mg-6,000 mg) over 24 hours have been reported to cause severe liver injury in some people, sometimes even resulting in death. It seems that certain individuals, for example, those who regularly drink alcohol, are more prone than others to developing acetaminophen-induced liver damage. Other factors that increase a person’s risk for damage from acetaminophen include the fasting state, malnutrition, and concomitant administration of some other drugs such as phenytoin (Dilantin), phenobarbital, carbamazepine [(Tegretol) (anti-seizure medications)] or isoniazid [(Nydrazid, Laniazid) (anti-TB drug)].
Statins are the most widely used medications to lower “bad” (LDL) cholesterol in order to prevent heart attacks and strokes. Most doctors believe that statins are safe for long-term use, and important liver injury is rare. Nevertheless, statins can injure the liver. The most common liver-related problem caused by statins is mild elevations in blood levels of liver enzymes (ALT and AST) without symptoms. These abnormalities usually improve or completely resolve upon stopping the statin or reducing the dose. There is no permanent liver damage.
Patients with obesity have an increased chance of developing diabetes, non-alcoholic fatty liver disease (NFALD), and elevated blood cholesterol levels. Patients with fatty liver often have no symptoms, and the abnormal tests are discovered when routine blood testing is done. Recent studies have found that statins can be used safely to treat high blood cholesterol in patients who already have fatty liver and mildly abnormal liver blood tests when the statin is started. In these patients, doctors may choose to use statins at lower doses and monitor liver enzyme levels regularly during treatment.
Nevertheless, idiosyncratic liver toxicity capable of causing severe liver damage (including liver failure leading to liver transplantation) has been reported with statins. The frequency of severe liver disease caused by satins is likely in the range of 1-2 per million users. As a precaution, the FDA labeling information advises that liver enzyme blood tests should be performed before and 12 weeks following the initiation of statin treatment or increase in dose, and periodically thereafter (for example, every six months).
Nicotinic acid (Niacin)
Niacin, like the statins, has been used to treat elevated blood cholesterol levels as well as elevated triglyceride levels. Also like the statins, niacin can damage the liver. It can cause mild transient elevations in blood levels of AST and ALT, jaundice, and, in rare instances, liver failure. Liver toxicity with niacin is dose-dependent; toxic doses usually exceed 2 grams per day. Patients with pre-existing liver diseases and those who drink alcohol regularly are at higher risk for developing niacin toxicity. The sustained-release preparations of niacin also are more likely to cause liver toxicity than the immediate-release preparations.
Amiodarone (Cordarone) is an important medication that is used to treat irregular heart rhythms such as atrial fibrillation and ventricular tachycardia. Amiodarone can cause liver damage ranging from mild and reversible liver blood enzyme abnormalities, to acute liver failure and irreversible cirrhosis. Mild liver blood test abnormalities are common and typically resolve weeks to months after stopping the drug. Serious liver damage occurs in less than 1% of patients.
Amiodarone differs from most other drugs because a substantial amount of amiodarone is stored in the liver. The stored drug is capable of causing fatty liver, hepatitis, and, more importantly, it can continue to damage the liver long after the drug is stopped. Serious liver damage can lead to acute liver failure, cirrhosis, and the need for liver transplantation.
Methotrexate (Rheumatrex, Trexall)
Methotrexate (Rheumatrex, Trexall) has been used for the long-term treatment of patients with severe psoriasis, rheumatoid arthritis, psoriatic arthritis, and some patients with Crohn’s disease. Methotrexate has been found to be a cause of liver cirrhosis in a dose-dependent fashion. Patients with pre-existing liver diseases, obese patients, and those who drink alcohol regularly are particularly at risk of developing methotrexate-induced cirrhosis. In recent years, doctors have substantially decreased methotrexate liver damage by using low doses of methotrexate (5 mg-15 mg) given once a week and by carefully monitoring liver blood tests during therapy. Some doctors also perform liver biopsies on patients without liver symptoms after 2 years (or after a cumulative dose of 4 grams of methotrexate) to look for early liver cirrhosis.
Isoniazid (Nydrazid, Laniazid). Isoniazid has been used for decades to treat latent tuberculosis (patients with positive skin tests for tuberculosis, without signs or symptoms of active tuberculosis). Most patients with isoniazid-induced liver disease only develop mild and reversible elevations in blood levels of AST and ALT without symptoms, but approximately 0.5%-1% of the patients develop isoniazid-induced hepatitis. The risk of developing isoniazid hepatitis occurs more commonly in older patients than in younger patients. The risk of serious liver disease is 0.5% in healthy young adults and rises to more than 3% in patients older than 50. At least 10% of the patients who develop hepatitis go on to develop liver failure and require liver transplantation. The risk of isoniazid liver toxicity is increased with chronic regular alcohol intake, and with concomitant use of other medications such as Tylenol and rifampin (Rifadin, Rimactane).
Early symptoms of isoniazid hepatitis are fatigue, poor appetite, nausea, and vomiting. Jaundice may then follow. Most patients with isoniazid hepatitis recover fully and promptly after stopping the drug. Severe liver disease and liver failure mostly occur in patients who continue to take isoniazid after the onset of hepatitis. Therefore, the most important treatment for isoniazid liver toxicity is early recognition of hepatitis and discontinuation of the isoniazid before serious liver injury has occurred.
Nitrofurantoin. Nitrofurantoin is an anti-bacterial drug that is used to treat urinary tract infections caused by many gram-negative and some gram-positive bacteria. (Nitrofurantoin was approved by the FDA in 1953.) There are three forms of nitrofurantoin available: a microcrystalline form (Furadantin), a macrocrystalline form (Macrodantin), and a sustained release, macrocrystalline form used twice daily (Macrobid).
Nitrofurantoin can cause acute and chronic liver disease. Most commonly, nitrofurantoin causes mild and reversible elevations in blood levels of liver enzymes without symptoms. In rare instances, nitrofurantoin can cause hepatitis.
Symptoms of nitrofurantoin hepatitis include
- muscle and joint aches,
- poor appetite,
- weight loss,
- jaundice, and
- sometimes itching.
Some patients with hepatitis also have a rash, enlarged lymph glands, and nitrofurantoin-induced pneumonia (with symptoms of cough and shortness of breath). Blood tests usually show elevated liver enzymes and bilirubin. Recovery from hepatitis and other skin, joint, and lung symptoms is usually rapid once the drug is stopped. Serious liver disease such as acute liver failure and chronic hepatitis with cirrhosis mostly occur in patients who continue the drug despite developing hepatitis.
Augmentin. Augmentin is a combination of amoxicillin and clavulanic acid. Amoxicillin is an antibiotic that is related to penicillin and ampicillin. It is effective against many bacteria such as H. influenzae, N. gonorrhea, E. coli, Pneumococci, Streptococci, and certain strains of Staphylococci, Addition of clavulanic acid to amoxicillin in Augmentin enhances the effectiveness of amoxicillin against many other bacteria that are ordinarily resistant to amoxicillin.
Augmentin has been reported to cause cholestasis with or without hepatitis. Augmentin-induced cholestasis is uncommon but has been implicated in hundreds of cases of clinically apparent acute liver injury. Symptoms of cholestasis (jaundice, nausea, itching) usually occur 1-6 weeks after starting Augmentin, but the onset of liver disease can occur weeks after stopping the Augmentin. Most patients recover fully in weeks to months after stopping the medication, but rare cases of liver failure, cirrhosis, and liver transplantation have been reported.
Other antibiotics have been reported to cause liver disease. Some examples include minocycline (an antibiotic related to tetracycline), and Cotrimoxazole (a combination of sulfamethoxazole and trimethoprim).
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed for the bone and joint-related inflammation such as arthritis, tendinitis, and bursitis. Examples of NSAIDs include aspirin, indomethacin (Indocin), ibuprofen (Motrin), naproxen (Naprosyn), piroxicam (Feldene), and nabumetone (Relafen). Approximately 30 million Americans take NSAIDs regularly!
NSAIDs are safe when used properly and as prescribed by doctors; however, patients with cirrhosis and advanced liver disease should avoid NSAIDs since they can worsen liver function (and cause kidney failure as well).
Serious liver disease (such as hepatitis) from NSAIDs, occur rarely (in approximately one in 10 patients per 100,000 who use prescriptions). Diclofenac (Voltaren) is an example of an NSAID that has been reported to cause hepatitis slightly more frequently, in approximately one to five per 100,000 users of the drug. Hepatitis usually resolves completely after stopping the drug. Acute liver failure and chronic liver disease, such as cirrhosis, have been reported rarely.
Tacrine (Cognex) is an oral medication used for treating Alzheimer’s disease. (The FDA approved tacrine in 1993.) Tacrine has been reported to cause abnormal elevations in blood liver enzymes commonly. Patients may report nausea, but hepatitis and serious liver disease are rare. Abnormal tests usually become normal after tacrine is stopped.
Disulfiram (Antabuse) is a medication occasionally prescribed to treat alcoholism. It discourages drinking by causing nausea, vomiting, and other unpleasant physical reactions when alcohol is ingested. Disulfiram has been reported to cause acute hepatitis. In rare cases, disulfiram-induced hepatitis can lead to acute liver failure and liver transplantation.
Vitamins and Herbs
Excess intake of vitamin A, taken for years, can damage the liver. It is estimated that more than 30% of the U.S. population takes supplements of vitamin A, and some individuals are taking vitamin A at high doses that may be toxic to the liver (greater than 40,000 units/ day). Vitamin A-induced liver disease includes mild and reversible elevation in blood liver enzymes, hepatitis, chronic hepatitis with cirrhosis, and liver failure.
The symptoms of vitamin A toxicity may include bone and muscle aches, orange discoloration of skin, fatigue, and headache. In advanced cases, patients will develop enlarged livers and spleens, jaundice, and ascites (abnormal buildup of fluid in the abdomen). Patients who drink alcohol heavily and have other preexisting liver diseases are at increased risk of liver damage from vitamin A. Gradual improvement in the liver disease usually occurs after stopping vitamin A, but progressive liver damage and failure may occur in severe vitamin A toxicity with cirrhosis.
Liver toxicity also has been reported with herbal teas. Examples include Ma Huang, Kava Kava, pyrrolizidine alkaloids in comfrey, germander, and chaparral leaf. Amanita phylloides is a liver-toxic chemical found in poisonous mushrooms. Consumption of a single poisonous mushroom can lead to acute liver failure and death.