Know about drugs with Chula pharmacists: Drugs that are toxic to the liver

    A few days ago, a user reached out with an interesting question about medication. This individual had several underlying health conditions, including diabetes, high blood pressure, and high cholesterol. Every doctor’s visit resulted in a prescription for multiple medications, with both the doctor and pharmacist emphasizing the necessity of taking 4-5 of these medications daily, which the patient diligently followed. However, the patient frequently wondered whether this regimen was overburdening their liver and kidneys, potentially leading to organ failure. How could the doctor and pharmacist be sure that the liver and kidneys remained healthy? How could the patient identify potential issues with these organs?

    First, I commend the patient for being proactive about their health and asking these important questions. Monitoring liver and kidney function can be done through regular blood tests, such as serum creatinine, AST, ALT, and bilirubin levels, which doctors periodically check for those on long-term medication.

    This week, let’s focus on preventing liver toxicity from drugs. Next week, we’ll discuss the kidneys. As you may know, the liver is responsible for metabolizing substances that enter the body, including chemicals and medications. When drugs are metabolized, some may be broken down by the liver, making it susceptible to injury, especially with high doses or prolonged use.

    When prescribing potentially liver-toxic drugs, doctors and pharmacists assess liver function first and continue periodic tests. Knowing which drugs are highly toxic to the liver can be valuable information.

    Types of Drugs That Pose a Risk of Liver Toxicity:

    Paracetamol (Acetaminophen): The most common cause of liver toxicity. Overdose or prolonged use, especially in regular alcohol drinkers, can lead to severe hepatitis.

    Some Antibiotics: Such as isoniazid and rifampin.

    Some Antifungals: Including ketoconazole and fluconazole.

    Antiepileptics: Such as valproate and phenytoin.

    Statin-type Cholesterol-lowering Drugs: Such as atorvastatin and simvastatin.

    Among these, paracetamol is the most widely used and available over-the-counter, making it a common household drug. Other drugs usually require a prescription and medical supervision.

    Safe Paracetamol Usage:

    Many people are aware that excessive paracetamol can cause liver toxicity. Adults should not exceed 8 tablets of 500 mg (4 grams) in 24 hours and should not take it for more than 5 consecutive days. For smaller adults (weighing less than 50 kg), the dosage should be adjusted to avoid liver toxicity.

    The recommended dosage is 10-15 mg per kg of body weight per dose, not exceeding 1,000 mg per dose. Doses should be spaced 4-6 hours apart and not exceed 4 grams per day.

    For instance:

    A patient weighing 45 kg should take 450-675 mg per dose (approximately one 500 mg tablet).

    A patient weighing 80 kg should take 800-1,000 mg per dose, but never exceed 1,000 mg per dose (two 500 mg tablets).

    Paracetamol packaging typically includes dosage recommendations based on weight.

    Symptoms of Liver Toxicity:

    Symptoms of liver toxicity are often nonspecific, such as loss of appetite, nausea, vomiting, fatigue, stomach pain, jaundice, and dark urine. If these symptoms appear shortly after starting a medication, liver toxicity may be suspected, and a visit to the hospital for diagnosis and treatment is necessary.

    Liver toxicity from medication is a serious issue that warrants attention. Taking medication under medical supervision and following advice can mitigate risks. Reducing or eliminating alcohol consumption can further reduce the risk of hepatitis and liver failure. If you have concerns or questions about medication, consult your doctor or pharmacist for safe and appropriate guidance.

Assoc. Prof. Dr. Nattada Areepiam and Assoc. Prof. Dr. Bodin Tiwasuwan

Faculty of Pharmacy Chulalongkorn University