Tracleer and PPH News Taking liver-taxing drugs calls for periodic testing RICHARD HARKNESS: AS PRESCRIBED - April 05, 2005 Q: My doctor wants to prescribe a cholesterol-lowering medication that requires periodic tests of my liver. Can you tell me what tests she's talking about and why they're needed? A: The liver's job is to break down drugs for elimination by the body. In some cases, the drug or some of its breakdown products can damage this organ. The tests your doctor mentioned are likely those that measure the levels of ALT and AST (liver enzymes) and bilirubin in your blood. Normal levels indicate your liver is healthy. When liver cells are damaged, these enzymes leak into the blood, resulting in higher levels. Bilirubin also can climb higher. The yellow discoloration of jaundice is caused by high bilirubin levels. Minimal elevations of liver enzymes may not be serious. The presence of significantly higher levels, however, especially when accompanied by high bilirubin levels, is a red flag. The good news is that drug-induced liver toxicity is relatively uncommon. The bad news is that when liver toxicity does occur, it can be sudden and serious. Early detection of a potential problem can prevent permanent liver damage. Generally, abnormal liver test values return to normal when the offending agent is stopped or the dosage reduced. It may be possible to restart a stopped medication at a later time. Unfortunately, the link between a drug and liver impairment may not surface until after the drug has been FDA-approved and in widespread use. In fact, serious drug-induced liver injury is the leading reason drugs are withdrawn from the market. Examples include bromfenac (Duract), ticrynafen (Selecryn), benoxaprofen (Oraflex) and troglitizone (Rezulin). Following is a representative list of drugs that call for liver function monitoring to help ensure safe use: Acarbose (Precose), amiodarone (Cordarone), amprenavir (Agenerase), atorvastatin (Lipitor), azathioprine (Imuran), bosentan (Tracleer), carbamazepine (Tegretol), celecoxib (Celebrex), dapsone, diclofenac (Voltaren, Arthrotec), efavirenz (Sustiva), ethotoin (Peganone), ethosuximide (Zarontin), felbamate (Felbatol), fenofibrate (Tricor), fluconazole (Diflucan), flutamide (Eulexin), fluvastatin (Lescol), gemfibrozil (Lopid), gemtuzumab (Mylotarg), griseofulvin (Gris-PEG), imatinib (Gleevec), indinavir (Crixivan), isoniazid, isotretinoin (Accutane), itraconazole (Sporanox), ketoconazole (Nizoral), ketorolac (Toradol), lamivudine (Epivir), leflunomide (Arava), lovastatin (Mevacor), meloxicam (Mobic), methotrexate (Rheumatrex), methsuximide (Celontin), methyldopa (Aldomet), nabumetone (Relafen), nefazodone (Serzone), naproxen (Naprosyn, Aleve), nevirapine (Viramune), niacin (Niaspan), nitrofurantoin (Macrodantin), oxaprozin (Daypro), peginterferon alfa-2a (Pegasys), pemoline Cylert), pentamidine (Pentam), pioglitazone (Actos), piroxicam (Feldene), pravastatin (Pravachol), pyrazinamide (Tebrazid), ribavirin (Rebetol), ribavirin/interferon alfa 2b (Rebetron), rifampin (Rifadin), riluzole (Rilutek), rosiglitazone (Avandia), rosuvastatin (Crestor), ritonavir (Norvir), simvastatin (Zocor), sulindac (Clinoril), tacrine (Cognex), tamoxifen (Nolvadex), terbinafine (Lamisal), testosterone (AndroGel, Testim), tizanidine (Zanaflex), tolcapone (Tasmar), valproic acid (Depakote), Voriconazole (Vfend) and zileuton (Zyflo). The over-the-counter pain-reliever acetaminophen can be toxic to the liver at higher-than-recommended doses. Herbs and dietary supplements that can injure the liver include chaparral, comfrey, coltsfoot, germander, kava, pennyroyal oil, skullcap, valerian root, androstenedione and DHEA. Combining these agents with each other or with alcohol amplifies the risk. Signs of possible liver dysfunction should be reported immediately: fatigue, abdominal pain, nausea and vomiting, appetite loss, dark urine and jaundice.
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Richard Harkness is a consultant pharmacist who writes on health care topics. You can write him at 1224 King Henry Drive, Ocean Springs, MS 39564 or e-mail rharkn@aol.com.
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