Can imipenem (IMI)/cilastatin cause thrombocytopenia?

Imipenem/Cilastatin and Thrombocytopenia

Yes, imipenem/cilastatin can cause thrombocytopenia as documented in the FDA drug label and confirmed by case reports. 1, 2

Evidence for Thrombocytopenia

• The FDA drug label for imipenem/cilastatin explicitly lists thrombocytopenia as a post-marketing adverse reaction 1
• A recent 2022 case report documented thrombocytopenia in an elderly patient with a clear temporal relationship between imipenem/cilastatin administration and platelet count decreases 2
• The patient experienced a dramatic decrease in platelet count on the 9th day after initial administration and again on the 4th day after re-administration 2
• The platelet count returned to normal levels after drug withdrawal in both instances, strongly suggesting a causal relationship 2

Hematologic Effects of Imipenem/Cilastatin

• The FDA drug label identifies several hematologic adverse reactions associated with imipenem/cilastatin, including:

  • Thrombocytopenia
  • Pancytopenia
  • Bone marrow depression
  • Neutropenia
  • Leukopenia
  • Hemolytic anemia 1

• In pediatric patients, laboratory changes included increased platelets in some cases, but decreased platelets in others 1

Clinical Significance and Management

• While thrombocytopenia is documented as an adverse effect, older studies suggest it may be relatively uncommon in standard clinical use 3
• A 1985 study of high-dose imipenem/cilastatin (1g IV every 6 hours) in 31 seriously ill patients reported no significant changes in platelet counts 3
• However, the FDA drug label and more recent case reports confirm that thrombocytopenia remains a recognized risk 1, 2
• Healthcare providers should monitor complete blood counts in patients receiving imipenem/cilastatin therapy, especially those on prolonged courses 2
• If thrombocytopenia develops, consider discontinuation of imipenem/cilastatin and switching to an alternative antimicrobial agent 2

Other Serious Hematologic Concerns

• Beyond thrombocytopenia, imipenem/cilastatin has been associated with more severe hematologic reactions:
  • A case of pure white cell aplasia (severe agranulocytosis with histological evidence) has been reported 4
  • Pancytopenia is listed as a post-marketing adverse reaction 1

Conclusion

Clinicians should be aware that thrombocytopenia is a recognized adverse effect of imipenem/cilastatin therapy. Regular monitoring of complete blood counts is advisable, particularly for patients on extended treatment courses or with pre-existing hematologic abnormalities.