Atorvastatin for the Treatment of Lithium-Induced Nephrogenic Diabetes Insipidus

Lithium remains the gold-standard treatment for bipolar disorder, with 30-40% of patients with responding preferentially to this medication. Additionally, lithium is commonly used in treatment-resistant depression, and other psychiatric disorders (e.g. schizoaffective disorder). Lithium is especially valuable considering the great difficulty in achieving and maintaining symptomatic remission, the high rates of disability, as well as tremendous personal, family, and societal costs associated with bipolar disorder and treatment-resistant depression. Despite this, clinicians are increasingly avoiding lithium, largely due to fear of irreversible chronic kidney disease (CKD), particularly in North America. It is well known that lithium exposure, even when dosed safely (\<1.0mmol/L in adults 11 and \<0.8mmol/L in geriatric patients 12,13), can increase the risk of CKD by 3 times, in large part through Nephrogenic Diabetes Insipidus (NDI) 14-19. NDI itself has also been associated with acute kidney injury 20, and life-threatening hypernatremia, which is an electrolyte imbalance characterized by high levels of blood sodium. Aside from hypertension, diabetes mellitus, aging, and other nonspecific CKD risk factors. NDI is characterized by excessive thirst (polydipsia) due to increased production of dilute urine (polyuria). In NDI, lithium is believed to interact with the inositol monophosphate and protein kinase C pathways, thereby affecting calcium-related intracellular signaling, cyclic AMP (cAMP), inhibition of Glycogen Synthase Kinase-3 Beta (GSK3Beta), activation of MAP Kinase and many other pathways. NDI occurs commonly in lithium users: 50% of chronic lithium users have urinary concentrating difficulties, with 12-19% have decreased urine osmolality (UOsm) \<300mOsm/Kg). To date, amiloride (5-20mg/day) is the only medication with prior evidence of therapeutic effectiveness in NDI from randomized clinical trials. However as a potassium-sparing diuretic 31, amiloride