Diclofenac- and Pantoprazole-Induced Rhabdomyolysis: A Potential Drug Interaction

Diclofenac and the Risk of Rhabdomyolysis: Analysis of Publications and the WHO Global Pharmacovigilance Database

Background

Diclofenac, a nonsteroidal anti-inflammatory drug, is not a documented cause of rhabdomyolysis in the Summaries of Product Characteristics held by major regulators. There are, however, eight published single case reports that associate rhabdomyolysis with diclofenac.

Objective

Triggered by a serious local case report, this study was conducted to evaluate the evidence for a causal association between diclofenac and rhabdomyolysis.

Patients and Methods

A descriptive analysis of rhabdomyolysis associated with diclofenac was conducted by mining data from the WHO Global Database of Individual Case Safety Reports, VigiBase, and published case reports.

Results

70 eligible cases were retrieved from VigiBase. The median age was 56.5 years (range 1–90). Where reported precisely (26 reports), the median time to onset of rhabdomyolysis following administration of diclofenac was 3 days. In 20 cases, diclofenac was reported as a sole suspect and was solely administered in 14 of these. In 30 cases, rhabdomyolysis abated following withdrawal of diclofenac. Seven of these cases fulfilled the WHO-UMC case-causality assessment criteria for ‘probable’. Diclofenac was probably an indirect cause in another five reports where rhabdomyolysis ensued from injection-site necrosis. There were eight fatalities and intramuscular administration was over-represented in this group. In 27 patients taking lipid-lowering agents, the incidence of acute kidney injury with rhabdomyolysis was 62.9% compared with 37.1% for the whole cohort. Off-label use of diclofenac for minor or undiagnosed conditions was reported.

Conclusion

Currently available data suggests a causal link between diclofenac and rhabdomyolysis either directly or indirectly.

Lipin-1 Deficiency-Associated Recurrent Rhabdomyolysis and Exercise-Induced Myalgia Persisting into Adulthood: A Case Report and Review of Literature

Phosphatidate phosphatase-1 (lipin-1) is encoded by LPIN1 gene. Lipin-1 deficiency has been reported as the second most common cause of early-onset rhabdomyolysis after primary fatty acid oxidation disorders. We report a case of a 32-year-old Sri Lankan female with a history of more than 10 episodes of rhabdomyolysis and exercise intolerance since childhood. These episodes were triggered by infections and exercise. A temporal relationship between the acute episodes and use of drugs such as theophylline, mefenamic acid, co-trimoxazole, and combined oral contraceptive pills was also noted. There was marked elevation of serum creatine kinase and transaminases during acute episodes. Family history revealed parental consanguinity and an affected sibling who died of an acute episode associated with muscle weakness, dark coloured urine, and cyanosis, at the age of 2 years. The histochemical findings of the patient under discussion were consistent with a metabolic myopathy affecting membrane integrity. A homozygous, likely pathogenic variant c.1684G>T encoding p.(Glu562∗) was identified by clinical exome sequencing. Even though the studies to date give no convincing evidence of a possible causal or contributory relationship between the drugs under discussion and lipin-1 related rhabdomyolysis, this case highlights the importance of pharmacovigilance and reporting adverse drug reactions in patients with lipin-1 deficiency.