title: A neutropenia suggesting an interaction between valacyclovir and mycophenolate mofetil.
abstract: 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.
authors.affiliation: Pharmacology Department, Jean Minjoz University Hospital, Besançon, France. bernard.royer@ufc-chu.univ-fcomte.fr
authors.forename: Bernard
authors.initials: B
authors.lastname: Royer
authors.forename: Gilbert
authors.initials: G
authors.lastname: Zanetta
authors.forename: Michel
authors.initials: M
authors.lastname: Bérard
authors.forename: Siamak
authors.initials: S
authors.lastname: Davani
authors.forename: Yves
authors.initials: Y
authors.lastname: Tanter
authors.forename: Gérard
authors.initials: G
authors.lastname: Rifle
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Kantelip
mesh_terms: 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*
chemical_list: D000998:Antiviral Agents; D007166:Immunosuppressive Agents; D014633:Valine; D009173:Mycophenolic Acid; D000077483:Valacyclovir; D000212:Acyclovir