Prescribing drugs for patients with liver disease

Adverse reactions to prescribed drugs are a common cause of morbidity in patients receiving medical care. Pre-existing or underlying liver dysfunction is one of the commonest factors that enhance the risk of such adverse events in medical practice. Most textbooks of medicine contain no guidelines on special precautions to be taken in prescribing to a patient with pre-existing liver disease.

To provide a ready reckoner for modifying drug dosage in liver diseases, a literature search was carried out. All papers related to human studies were reviewed and relevant material extracted for preparing the guidelines.

Most adverse drug reactions in the presence of liver disease are related to altered pharmacokinetics, pharmacodynamics and susceptibility to drugs. The influence of hepatic disease on various drugs is highly variable. However, many such adverse events are predictable and preventable. Ideally, drug dosage should be modified with the help of serum drug concentrations, which unfortunately, are not available in most Indian hospitals. Hence, some broad guidelines are presented to assist the treating physician to be aware of the risk of adverse drug reactions and modify drug dosage empirically to avoid such events.

The altered metabolism of pharmacological agents in patients with liver disease may induce several undesirable effects. A large number of adverse drug reactions can be prevented by modifying drug prescribing habits for patients who have pre-existing liver disease.