Pemoline (Cylert)-induced hepatotoxicity

Which psychotropic medications induce hepatotoxicity?

OBJECTIVE

Safe prescribing practices to minimize pharmaceutically induced liver damage or worsening of preexisting conditions require knowledge about medicines with hepatotoxic potential. This paper reviews psychotropic medications and their effects on the liver.

METHODS

A MEDLINE search was performed utilizing the phrase "drug-induced liver injury" with various categories of psychiatric drugs. Only articles written in English were utilized.

RESULTS

Hepatotoxicity can be acute or chronic in nature. Medication discontinuation is necessary in acute forms, while close monitoring is required in milder forms of medication-induced chronic liver damage. Nefazodone, pemoline and/or tacrine are the highest offenders. Carbamazepine and valproate products (e.g., divalproex) can lead to this adverse event and should be avoided in patients with liver disease, persons with alcohol misuse or those consuming high doses of acetaminophen.

CONCLUSION

Knowing the risk levels associated with various medicines is important; prescribing multiple drugs with hepatotoxic effects should be avoided. One should educate patients about early warning signs of liver injury. Always provide clinical and laboratory monitoring before and during the use of hepatotoxic drugs. Clinical features and laboratory results govern medication prescribing with ongoing risk-to-benefit ratio assessment during pharmacotherapy.

Effectiveness of risk management plans: a case study of pemoline using pharmacy claims data

PURPOSE

To assess the effectiveness of a pharmaceutical risk management plan using pemoline as a case study and pharmacy claims as the data source.

METHODS

Prescription claims from a continuously enrolled US population (September 1, 2000-September 30, 2002) from Caremark, a pharmacy benefit manager, were evaluated for patients with one or more pemoline claims. Patients were categorized using pemoline as second-line or first-line therapy depending on presence or absence of other central nervous system (CNS) stimulants prescriptions 90 days prior to the first pemoline claim. Logistic regression was performed to compare second-line and first-line usage with regard to patient age, gender and prescribing physician specialty and region of practice.

RESULTS

Of 1,279,296 prescription claims for CNS stimulants, 17,256 (1.3%) were for pemoline. Nine hundred thirteen patients received pemoline and had 90 days or more prior enrollment. Overall, 10% of patients receiving pemoline received it as second-line therapy (95%CI: 8-12%). After adjusting for age, gender, specialty, and region, the odds of receiving pemoline as second-line therapy were significantly greater in pediatrics relative to adults (OR = 2.82, 95%CI: 1.58-5.03), and among those whose prescribers were psychiatrists versus primary care physicians (OR = 2.48, 95%CI: 1.37-4.50). Children treated by a psychiatrist had the greatest likelihood for use as second-line therapy (36%, 95%CI: 19-56%).

CONCLUSIONS

Among patients who received pemoline, concordance with second-line therapy recommendations was low, even among the primary target audience of children. These results in a large geographically diverse patient population are consistent with an earlier regional study.

A study of compliance with FDA recommendations for pemoline (Cylert)

OBJECTIVE

To assess compliance with product labeling recommendations to use pemoline as second-line therapy for attention-deficit/hyperactivity disorder (ADHD) and to obtain baseline and biweekly liver enzyme tests.

METHOD

Retrospective cohort study using administrative claims data to identify first-line therapies and liver enzyme tests among pemoline users between January 1, 1998, and March 31, 2000. Prescriptions for first-line therapy were searched for 90 days prior to the first pemoline claim. Liver enzyme testing (baseline and follow-up) was compared between two groups (the prerecommendation cohort October 1,1998, to March 31, 1999, and the postrecommendation cohort October 1,1999, to March 31,2000).

RESULTS

1,308 patients received at least one pemoline prescription during the study period; 76% of patients < or = 20 years were male. ADHD was the claims-identified indication for 688 patients (52%). Despite the labeling recommendation for use as second-line therapy, only 237 ADHD patients (34%) received a first-line therapy prior to pemoline. Only 12% and 11% of the pre- and post-cohort patients, respectively, received baseline liver enzyme tests; 9% in the pre- and 12% in the post-cohort received at least one liver enzyme follow-up test.

CONCLUSIONS

Compliance with product labeling was low for both recommendations. Understanding the reasons for this finding could help improve risk management strategies.

Pemoline hepatotoxicity and postmarketing surveillance

OBJECTIVE

To review the numerous reports of hepatotoxic adverse drug reactions (ADRs) ascribed to pemoline that were sent to the U.S. Food and Drug Administration (FDA) between 1975 and 1996 and to describe the medical community's lack of awareness of these reports.

METHOD

All ADR reports from 1975 through 1996 wherein pemoline was the suspect agent were obtained from the FDA MedWatch Internet site, and some details of nine pemoline-related deaths in youths were obtained directly from the FDA. The published literature on this subject was fully reviewed.

RESULTS

(1) In premarketing clinical trials with pemoline in the early 1970s, hepatic abnormalities were noted in enzyme levels (1%-3% of youths receiving maintenance treatment), during rechallenges (6 of 6), and in biopsies (2 of 2). (2) Between 1975 and 1989, 12 cases of jaundice and 6 deaths in youths ascribed to pemoline hepatotoxicity were reported to the FDA. (3) The first medical literature report of a serious ADR ascribed to pemoline was in a 1989 letter to the editor. (4) Physicians generally only became aware of serious pemoline hepatotoxicity in December 1996. (5) Pemoline use increased until 1997.

CONCLUSION

Limitations in postmarketing surveillance and public reporting in the United States, particularly in the 1980s, largely accounted for delays in an appropriate response to pemoline hepatotoxicity.

Drug-induced liver disease

The past year has seen several additions to the list of drugs that cause hepatic injury. Many of these agents produce fulminant hepatic necrosis and, in some cases, were withdrawn from the market (eg, bromfenac). Other drugs had warnings placed in their labeling along with stringent monitoring guidelines to alert physicians and patients alike to the potential for severe hepatic injury (eg, troglitazone, tolcapone). New reports of hepatoxicity continued to appear for many older agents, in some cases expanding the hepatotoxic spectrum for the drugs. Vanishing bile duct syndrome has drawn increasing attention and is now associated with more than 30 drugs. Ibuprofen is among those drugs newly described as causing this syndrome. Hepatitis C virus infection was reported as a possible risk factor for ibuprofen hepatotoxicity, raising the issue of safe use of nonprescription as well as prescription drugs in patients with underlying liver disease. Reports have appeared about acetaminophen-induced hepatotoxicity in several dozen children from unintentional overdoses, in addition to cases of therapeutic misadventure in adults.

The use of psychostimulants in the pediatric patient

The psychostimulant drugs have a long history of safe and effective usage in the treatment of ADHD. They remain the drugs of first choice in this condition. Children with ADHD should be aggressively treated with at least two different classes of psychostimulants before moving to nonpsychostimulant agents. As long as side effects are not troublesome, higher dosages may be used to adequately control the ADHD symptoms, and such high dosages do not impair learning. No evidence shows long-term effects of psychostimulants on growth. Effective use of the psychostimulants is essential for any clinician involved in the treatment of children with ADHD.

Pemoline hepatotoxicity in children

Pemoline hepatotoxicity ranges from asymptomatic elevations in levels of serum aminotransferases to fulminant liver failure. We report five cases of pemoline hepatotoxicity in children (four boys, one girl), including the only reported case resulting in orthotopic liver transplantation. We conclude that pemoline causes toxic liver damage in children. The severity of the damage is highly variable, and its onset may be late in the course of treatment. Pemoline and methylphenidate may act synergistically to cause liver damage. The levels of serum aminotransferases should be monitored throughout treatment with these agents.

Alertness-enhancing drugs as a countermeasure to fatigue in irregular work hours

Irregular work/rest patterns frequently cause disturbed sleep and excessive sleepiness and accidents. This review is focused on four pharmacological countermeasures-the "new" drugs modafinil and pemoline, the traditional caffeine, and, as a reference, amphetamine. It is concluded that there is still too little data available to decide whether systematic use of alertness-enhancing drugs is feasible in occupational settings. D-Amphetamine is ruled out because of its abuse potential and mood effects. Modafinil and pemoline have not been tested in field situations, whereas caffeine certainly is used to improve alertness during work, but the use is spontaneous/ad hoc, and there is still a lack of data on its systematic application. Particularly, the optimal amount and pattern of administration need elucidation.

Pemoline-associated hepatic failure: a critical analysis of the literature

Pemoline is a central nervous system (CNS) stimulant approved for use as part of the comprehensive medical management of attention deficit hyperactivity disorder (ADHD). An increased risk of acute hepatic failure is believed to be associated with pemoline usage, raising concerns about its prescription. A descriptive meta-analysis of the existing scientific literature and drug reporting databases was undertaken to provide more accurate understanding of this possible risk. The analysis appears to indicate that current assumptions of the risk of acute hepatic failure posed by pemoline usage alone are overestimates. Several recommendations regarding hepatic monitoring in the setting of pemoline prescription are provided.

Pemoline-associated fulminant liver failure: testing the evidence for causation

BACKGROUND

Pemoline is a central nervous system stimulant used in treating children with attention deficit-hyperactivity disorder. Hepatotoxicity has been commonly reported in association with pemoline; however, only two reports of cases of fatal liver failure have been published.

OBJECTIVES

We report on a 14-year-old boy who received concomitant pemoline and methylphenidate in whom fulminant liver failure occurred and for whom liver transplantation failed. Other causes of fulminant liver failure were ruled out, and the liver biopsy was suggestive of drug toxicity. We estimated the probability that these three cases represent an increased risk of fulminant liver failure associated with pemoline.

RESULTS

Based on the three known cases of fatal liver failure associated with pemoline use, we calculated that a child receiving pemoline has a relative risk of development of fulminant liver failure of 45.3 (95% confidence interval, 4.1 to 510). This highly significant association (p < 0.001) suggests causation.

CONCLUSIONS

Because pemoline has been widely used in recent years, further studies are needed to better quantify this risk in children with attention deficit-hyperactivity disorder.

Methylphenidate-induced hepatotoxicity in mice and its potentiation by beta-adrenergic agonist drugs

Methylphenidate hydrochloride, when administered as a single 75 to 100 mg/kg i.p. dose, was found to produce hepatic necrosis in male ICR mice. Peak hepatotoxicity, as measured by serum ALT elevations, occurred 16 hours post-treatment while maximal histopathological evidence of hepatotoxicity occurred 24-48 hours after the methylphenidate dose. Liver injury measured by either method was essentially nonexistent for dosages < or = 50 mg/kg in male mice, and was only minimally evident in female mice at the highest dosage testable. Co-treatment of mice with either alpha 1- or alpha 2-adrenergic agonist drugs had no meaningful effect on methylphenidate-induced hepatotoxicity. In contrast, the beta-adrenergic agonist drug isoproterenol produced a striking potentiation of the liver injury, and shifted the apparent threshold for toxicity approximately 5- to 10-fold. Co-administration of methylphenidate with the mixed alpha/beta-adrenergic agonist dobutamine or with the beta 2-selective agonists metaproterenol, ritodrine or terbutaline produced a similar potentiation of toxicity. Parallel tests with beta-adrenergic antagonists revealed that the potentiation by isoproterenol could be significantly diminished by a single dose of the non-selective beta-adrenoreceptor blocking drug nadolol or the beta 2-selective antagonist ICI-118,551, but not the beta 1-selective antagonist metoprolol. Collectively, these observations suggest that potentiation of methylphenidate hepatotoxicity occurs through stimulation of beta 2-adrenoreceptors. Mice co-treated with isoproterenol were found to have substantially higher serum and liver methylphenidate levels following the methylphenidate dose, and significant increases were also observed in the area-under-the-curve (AUC) for methylphenidate in both tissues of isoproterenol co-treated mice. The results of this study suggest that beta 2-adrenergic agonist drugs are capable of potentiating methylphenidate-induced hepatotoxicity in mice by increasing hepatic methylphenidate concentrations.