A neutropenia suggesting an interaction between valacyclovir and mycophenolate mofetil.
Mycophenolate mofetil (MMF) is a drug which decreases the frequency of renal transplantation rejection. However, cytomegalovirus infections are a common feature of this treatment leading the physicians to prescribe antiviral prophylactic drugs like valacyclovir. During this association, neutropenia occur and the cause of this adverse effect is difficult to define. This report presents a case of neutropenia in a woman treated with MMF and valacyclovir. As the duration of the valacyclovir treatment exactly corresponds to the neutropenia duration, and the mycophenolate trough levels increased with the neutrophil count, the responsibility of this neutropenia was ascribed to valacyclovir. However, an examination of the literature for cases of neutropenia led to the suspicion of an interaction between MMF and valacyclovir. Mycophenolate may increase intracellular concentrations of valacyclovir up to haematotoxic levels. This mechanism may explain the interaction and further research is needed to confirm this interaction.
Royer
Bernard
B
Pharmacology Department, Jean Minjoz University Hospital, Besançon, France. bernard.royer@ufc-chu.univ-fcomte.fr
Zanetta
Gilbert
G
Bérard
Michel
M
Davani
Siamak
S
Tanter
Yves
Y
Rifle
Gérard
G
Kantelip
Jean-Pierre
JP
D000212:Acyclovir / Q000009:adverse effects* / Q000031:analogs & derivatives*; D000998:Antiviral Agents / Q000009:adverse effects*; D003586:Cytomegalovirus Infections / Q000188:drug therapy; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D016030:Kidney Transplantation; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000009:adverse effects* / Q000031:analogs & derivatives; D009503:Neutropenia / Q000139:chemically induced*; D000077483:Valacyclovir; D014633:Valine / Q000009:adverse effects* / Q000031:analogs & derivatives*
D000998:Antiviral Agents; D007166:Immunosuppressive Agents; D014633:Valine; D009173:Mycophenolic Acid; D000077483:Valacyclovir; D000212:Acyclovir