Does Ranexa (ranolazine) affect white blood cell (WBC) count?

Ranolazine (Ranexa) and White Blood Cell Count

Ranolazine (Ranexa) does not significantly affect white blood cell count based on available evidence, though rare cases of leukopenia, thrombocytopenia, and pancytopenia have been reported in post-marketing surveillance. 1

Hematologic Effects of Ranolazine

Ranolazine is an antianginal medication that works primarily through inhibition of the late sodium current, preventing intracellular calcium overload 2. Unlike some other cardiovascular medications, ranolazine has a relatively favorable safety profile with respect to hematologic parameters:

• The FDA drug label for ranolazine mentions leukopenia, thrombocytopenia, and pancytopenia as potential adverse reactions, but these are classified as rare events (occurring in <0.5% of patients) 1
• These hematologic effects were observed more frequently with ranolazine than placebo in controlled studies, but the absolute incidence remains very low 1
• No requirement for routine WBC monitoring exists for ranolazine, unlike medications such as clozapine which can cause agranulocytosis in approximately 1% of patients 2

Common Side Effects of Ranolazine

The most frequently reported adverse reactions with ranolazine (>4% and more common than placebo) are:

• Dizziness (6.2%)
• Headache (5.5%)
• Constipation (4.5%)
• Nausea (4.4%) 1

Laboratory Abnormalities with Ranolazine

While ranolazine does affect some laboratory parameters, its primary laboratory effect is on renal markers rather than hematologic parameters:

• Ranolazine consistently produces elevations of serum creatinine by approximately 0.1 mg/dL, regardless of previous renal function 1
• This elevation is believed to occur due to inhibition of tubular secretion of creatinine rather than actual renal impairment 1
• The creatinine elevation typically has a rapid onset, shows no progression during long-term therapy, and is reversible after discontinuation 1

Clinical Implications and Monitoring

For patients taking ranolazine:

• Routine WBC monitoring is not required specifically for ranolazine therapy 3
• Standard laboratory monitoring as appropriate for the patient's underlying conditions and other medications should be continued
• If a patient develops signs of infection or unusual bleeding while on ranolazine, checking complete blood count would be prudent
• More careful monitoring may be warranted in patients with pre-existing hematologic disorders or those taking other medications that may affect blood cell counts

Drug Interactions and Special Populations

Ranolazine has numerous drug interactions due to its metabolism by CYP3A enzymes and CYP2D6, but these primarily affect ranolazine levels rather than hematologic parameters:

• Ranolazine is extensively metabolized by CYP3A enzymes and to a lesser extent by CYP2D6 4
• Concomitant use with strong CYP3A inhibitors is contraindicated 3
• Ranolazine is contraindicated in patients with hepatic impairment or liver cirrhosis 3

Conclusion

While ranolazine has been associated with rare cases of leukopenia, thrombocytopenia, and pancytopenia in post-marketing surveillance, it does not commonly or significantly affect white blood cell counts in most patients. The medication's primary laboratory effect is on serum creatinine rather than hematologic parameters.