UMEM Educational Pearls

The liver performs an essential role in the metabolism and clearance of many drugs. Liver damage due to cirrhosis can decrease first-pass metabolism of oral medications and increase free-drug concentrations of protein-bound medications due to decreased albumin production. In the absence of cirrhosis, patients with chronic hepatitis or hepatic cancer may only have a small decrease in drug clearance. Hepatic dose adjustments are not as prevalent or readily available as renal dose adjustments, which can create difficulty in finding the balance between pain relief and adverse effects.

The most common medications used for pain control in the emergency department are acetaminophen, NSAIDs, and opioids.

Acetaminophen

It is sometimes misconceived that acetaminophen should never be used in patients with cirrhosis due to the common knowledge that acetaminophen overdoses can cause hepatotoxicity. Alcoholics may have an increased risk of hepatotoxicity due to induction of CYP2E1 and decreased glutathione stores. However, acetaminophen is safe in patients with cirrhosis when used at appropriate doses. Limit the total daily dose of acetaminophen to 2 g daily in patients with cirrhosis and avoid acetaminophen in patients that are actively drinking.  Also, educate patients that over-the-counter (OTC) and prescription medications may contain acetaminophen.

NSAIDs

In patients with cirrhosis, NSAIDs have increased bioavailability due to decreased CYP metabolism and decreased protein binding. In addition, prostaglandin inhibition can precipitate renal failure and sodium retention, worsening ascites and increasing the risk of hepatorenal syndrome, and increase the risk of gastrointestinal bleeding. Thrombocytopenia from NSAID use can further increase the risk of bleeding. Thus, avoid NSAID use in patients with cirrhosis. Topical NSAIDs can be considered.

Opioids

Opioid metabolism is altered in patients with cirrhosis and can contribute to complications with cirrhosis, such as precipitating encephalopathy. Generally, the bioavailability is increased and half-life is extended; thus, lower doses of immediate-release (IR) formulations at extended dosing intervals should be utilized. Common opioids for acute pain control in the emergency department are fentanyl, hydrocodone/oxycodone, hydromorphone, and morphine.

• Fentanyl: Largely unaffected by cirrhosis. High potency so utilize only in appropriate clinical situations.
• Hydrocodone/Oxycodone: Metabolized by CYP to active metabolites (hydromorphone/oxymorphone). Due to decreased CYP metabolism, analgesia may be less potent and clearance decreased. Also, be aware that some formulations are combined with acetaminophen.
• Hydromorphone: Metabolized by glucuronidation to inactive metabolite. Metabolism and clearance less affected by cirrhosis.
• Morphine: Increased bioavailability and concentration due to decreased first-pass metabolism. Decreased clearance and longer half-life. Avoid use in renal impairment and hepatorenal syndrome due to risk of neurotoxic metabolite accumulation.
• Tramadol, codeine, meperidine, methadone, and buprenorphine not recommended for acute pain control in the emergency department.

 

 

Take Home Points

Drug/Class	Preferred Agent	Considerations
Acetaminophen	Max daily dose 2 g/day	Avoid if actively drinking. Be cautious if patient also taking OTC or combination products.
NSAIDs	None; Avoid	Topical NSAIDs may be considered.
Opioids	Hydromorphone, Fentanyl	Start with IR products at lower doses and extended intervals.

 

References