Increased serum lithium concentration secondary to treatment with tiaprofenic acid and fosinopril.
OBJECTIVE
To describe a patient in whom the administration of tiaprofenic acid and fosinopril was associated with decreased lithium clearance, resulting in increased serum lithium concentrations.


METHODS
A woman treated with lithium for bipolar affective disorder was concurrently treated with tiaprofenic acid 200 mg tid for shoulder pain. Previously initiated treatment with fosinopril was maintained during this time. The urinary lithium clearance was decreased during this combination therapy, necessitating a reduction in the lithium dosage.


CONCLUSIONS
Lithium is approximately 80% reabsorbed in the proximal tubule, and the addition of tiaprofenic acid may have resulted in enhanced tubular lithium reabsorption. The possible influence of concurrent fosinopril therapy may also have contributed to altered lithium pharmacokinetics in this case.


CONCLUSIONS
Serum lithium concentrations should be monitored if patients taking lithium are treated with tiaprofenic acid.
Alderman
C P
CP
Pharmacy Department, Repatriation General Hospital, South Australia.
Lindsay
K S
KS
D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects* / Q000627:therapeutic use; D001714:Bipolar Disorder / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005260:Female; D017328:Fosinopril / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D008094:Lithium / Q000097:blood* / Q000652:urine; D008657:Metabolic Clearance Rate / Q000187:drug effects; D011422:Propionates / Q000009:adverse effects* / Q000627:therapeutic use
D000806:Angiotensin-Converting Enzyme Inhibitors; D000894:Anti-Inflammatory Agents, Non-Steroidal; D011422:Propionates; C021270:tiaprofenic acid; D008094:Lithium; D017328:Fosinopril