mycophenolic-acid and Histiocytosis--Langerhans-Cell

Langerhans cell histiocytosis (LCH) with multiple organ involvement is a rare disorder in adults. Extrapituitary involvement of the central nervous system (CNS) is uncommon. We report the unusual case of a 55-year-old woman presenting with a left-sided hemiataxia-hemiparesis, left hemisensory loss and short-lasting episodes of an alien left hand due to lesions of the internal capsule and the right thalamus, extending into the mesencephalon associated with extensive surrounding edema, without pituitary involvement. The neuroradiological image suggested glioblastoma multiforme. Brain biopsy revealed inflammatory tissue and "pseudotumoral" multiple sclerosis was suspected. Biopsy of concomitant lung and bone lesions disclosed Langerhans cell histiocytosis. The treatment with pulsed steroids in association with mycophenolate mofetil led to a sustained, clinical neurological remission.

Topics: Age of Onset; Alien Limb Phenomenon; Biopsy; Bone and Bones; Brain; Brain Diseases; Brain Neoplasms; Cerebellar Ataxia; Dexamethasone; Diagnosis, Differential; Drug Therapy, Combination; Female; Glioblastoma; Histiocytosis, Langerhans-Cell; Humans; Lung; Magnetic Resonance Imaging; Middle Aged; Multiple Sclerosis; Mycophenolic Acid; Paresis

The tuberculostatic compound rifampin (INN, rifampicin) induces the expression of a number of drug metabolism-related genes involved in multidrug resistance (P-glycoprotein and multidrug resistance proteins 1 and 2), cytochromes (cytochrome P450 [CYP] 3A4), uridine diphosphate-glucuronosyltransferases, monoamine oxidases, and glutathione S -transferases. Drugs that depend on these enzymes for their metabolism are prone to drug interactions when coadministered with rifampin. A novel, clinically relevant drug interaction is described between rifampin and mycophenolate mofetil (MMF), a cornerstone immunosuppressive molecule used in solid organ transplantation. Long-term rifampin therapy caused a more than twofold reduction in dose-corrected mycophenolic acid (MPA) exposure (dose-interval area under the concentration curve from 0 to 12 hours [AUC 0-12]) when administered simultaneously in a heart-lung transplant recipient, whereas subsequent withdrawal of rifampin resulted in reversal of these changes after 2 weeks of washout (dose-corrected AUC 0-12 after rifampin withdrawal, 19.7 mg.h.L-1.g -1 versus 6.13 mg.h.L-1.g-1 before rifampin withdrawal [221% change]; dose-uncorrected AUC 0-12 after rifampin withdrawal, 29.6 mg.h/L [daily MMF dose, 3 g] versus 18.4 mg.h/L [daily MMF dose, 6 g] during rifampin administration [60.8% change]). Failure to recognize this drug interaction could potentially lead to MPA underexposure and loss of clinical efficacy. The effect of rifampin on MPA metabolism can, at least in part, be explained by simultaneous induction of renal, hepatic, and gastrointestinal uridine diphosphate-glucuronosyltransferases and organic anion transporters with subsequent functional inhibition of enterohepatic recirculation of MPA.

Topics: Area Under Curve; Chronic Disease; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Interactions; Drug Therapy, Combination; Enterohepatic Circulation; Glucuronosyltransferase; Heart-Lung Transplantation; Histiocytosis, Langerhans-Cell; Humans; Hypertension, Pulmonary; Male; Metabolic Clearance Rate; Middle Aged; Mycophenolic Acid; Pharmacology, Clinical; Respiratory Insufficiency; Rifampin; Tacrolimus; Time Factors; Uridine Diphosphate; Withholding Treatment