PACE Case: Hydrochlorothiazide and Lithium

A 64-year-old African-American male with a history of hypertension, coronary artery disease, and schizophrenia is newly enrolled in PACE.

The participant’s medication regimen includes:

• Amlodipine, 5mg QD
• Acetylsalicylic acid, 81mg QD
• Fluphenazine decanoate 50mg, q2 weeks
• Lithium ER, 450mg BID
• Valsartan, 160mg QD (changed to Losartan, 100mg QD due to shortage)
• Zyprexa, 10mg QHS

His blood pressure is relatively well controlled upon admission, but two weeks later is elevated at 184/89, which may have been related to the change to Losartan. Since multiple studies analyzing hypertension treatment in African American patients have shown good results with Thiazide-type diuretics, the PACE nurse practitioner added Hydrochlorothiazide 25mg QD.

A CareKinesis pharmacist informed the nurse practitioner of the interaction between Hydrochlorothiazide and Lithium, and suggested a 50% decrease in the Lithium. Due to the participant’s psychiatric history, the nurse practitioner decided not to make any dose adjustments to the Lithium and would follow-up by checking his levels in two weeks.

A month later, the participant’s family contacted the PACE center stating that the participant was not acting himself. They reported that he was experiencing a loss of appetite, “acting like a zombie”, unable to tie his shoes, and said he was having a hard time thinking. Once in the clinic, the participant stated that he was dizzy. His Lithium levels were drawn and results were elevated, at 2.6 mmol/L (0.6 – 1.2).

The Hydrochlorothiazide was stopped and the participant’s blood pressure was then managed with Amlodipine and Losartan.