Liver disease and drug therapy

Therapeutic options in patients with lymphoma and severe liver dysfunction

OBJECTIVES

To determine the long-term outcome of patients presenting with synchronous lymphoma and severe liver dysfunction and to describe the outcome of patients treated with initial mechlorethamine-based therapy used as a bridge to more conventional chemotherapy.

PATIENTS AND METHODS

We reviewed the clinical course of all patients diagnosed as having lymphoma who presented with severe liver dysfunction and received intravenous mechlorethamine between September 1988 and February 2003 at the Mayo Clinic in Rochester, Minn.

RESULTS

Forty-one patients were identified, 33 (80%) of whom had newly diagnosed, previously untreated lymphoma. Thirty-seven (90%) had non-Hodgkin lymphoma, and 4 (10%) had Hodgkin disease. Thirty-four patients (83%) had stage IV disease, and 31 (84%) of 37 had an intermediate-high International Prognostic Index. The median total bilirubin level before therapy was 10.7 mg/dL (range, 2.5-30.2 mg/dL), and the median alkaline phosphatase level was 982 U/L (range, 233-3415 U/L). In addition to mechlorethamine, 34 patients (83%) received concomitant corticosteroids, and 12 (29%) received concomitant rituximab. Twenty-two patients (54%) had sufficient improvement in liver function to receive subsequent standard chemotherapy. Nine patients (22%) are alive and disease-free at a median of 31 months (range, 4 to > or = 87 months) after mechlorethamine treatment. Factors associated with improved overall survival included improvement in bilirubin levels (P < .001) and receiving subsequent standard chemotherapy (P = .001).

CONCLUSION

Mechlorethamine, high-dose corticosteroids, and rituximab are useful therapeutic interventions for this unique group of patients with lymphoma and severe liver dysfunction. Substantial clinical improvement and long-term survival are possible.

Elimination of pindolol in liver disease

The elimination of pindolol was studied in 32 patients suffering from various liver diseases, mainly acute hepatitis and hepatic cirrhosis. The total body clearance of antipyrine was measured simultaneously as a parameter of liver microsomal enzyme activity. The doses given were antipyrine 1000 mg orally and pindolol 3 mg i.v. Plasma samples were taken and urine was collected for up to 72 h for the measurement of drug concentrations. In addition, conventional biochemical laboratory tests were done. The total body clearance of antipyrine was compared with the pharmacokinetic parameters calculated for pindolol, and the results of the biochemical tests. No correlation was found between antipyrine clearance and the routine biochemical parameters in liver disease or with the total body clearance of pindolol. A significant correlation was seen with the nonrenal clearance of pindolol taken as representing its major metabolic degradation. Higher correlation coefficients were observed when two subgroups of patients with acute hepatitis and hepatic cirrhosis were separated. In some patients suffering from hepatic cirrhosis a higher urinary excretion of unchanged pindolol was observed as liver function become decompensated, a finding due to an unknown mechanism but based on intact renal function. In patients with acute hepatitis a much higher nonrenal clearance was found than in many other patients, which might be based on increased liver blood flow.

Protein binding and kinetics of drugs in liver diseases

Although the liver is the major site for drug biotransformation, the effect of hepatic dysfunction on drug disposition has not been consistent or predictable. Most early studies of drug kinetics in liver disease measured only half-life. Only in the past few years has it been realised that liver diseases can affect drug absorption, hepatic metabolism, tissue distribution, and protein binding, which complicate interpretation of any change, or lack of change in drug half-life. Furthermore, it is now apparent that the efficiency with which a drug is metabolised by the liver, the extent of binding to blood constituents, and the aetiology and stage of the hepatic disorder are each important in determining whether significant alterations in drug disposition will occur. A pharmacokinetic perfusion model which takes into account many of the above factors has been proposed, and appears to be useful for predicting changes in the disposition of rapidly metabolised compounds. Nevertheless, the state of knowledge about those factors which limit the rate of metabolism of individual drugs or classes of drugs in inadequate, and no general model or guidelines which are useful clinically have been developed. Patients with hepatic disorders may show increases or decreases in sensitivity independent of alterations in drug disposition. The clinician caring for such patients must be cautious about the use of any drugs, and rely heavily on careful patient observation to determine efficacy or toxicity.