Effect of a Proposed Cav1.3 Inhibitor in Primary Aldosteronism

The goal of this pilot, open-label prospective study is to evaluate if the effect of calcium channel blockade on plasma aldosterone levels in people with primary aldosteronism (PA) is due primarily to Cav1.3 blockade.This will be tested by treating participants who have PA with both cinnarizine (Cav1.3 blocker) and nifedipine (Cav1.2 blocker) and evaluating effect on aldosterone levels and blood pressure over a two week course of treatment.

Inclusion Criteria:Confirmed PA, as demonstrated by a positive screening test and internationally endorsed confirmatory test (saline suppression test, captopril challenge test)Adults > 18 years of ageAble and willing to give informed consentExclusion Criteria:Uncontrolled hypertension requiring use of MRAUnwilling or unable to give consentBelow age 18 or above age 90 yearsAllergy to cinnarizine or nifedipine or their excipientsExisting use of cinnarizine or nifedipine for an alternative indicationBreastfeeding or pregnant womenDiagnosis of Parkinson's diseaseSevere hepatic or renal insufficiencyConcurrent use of sedating central nervous system (CNS) depressants or rifampicinPorphyriaCardiogenic shock, clinically significant aortic stenosis, unstable angina, within one month of a myocardial infarctionPrevious gastro-intestinal or oesophageal obstruction or ileostomy