CLINICAL AND IMMUNOLOGICAL RESPONSE TO NIFEDIPINE FOR THE TREATMENT OF INTERSTITIAL CYSTITIS

Nifedipine is a calcium channel antagonist known to inhibit smooth muscle contraction and cell-mediated immunity. The clinical and local immune response to nifedipine was investigated in an open trial with 10 female interstitial cystitis patients, whose disease was diagnosed according to the consensus criteria developed in 1987 at a National Institutes of Health workshop. To evaluate the symptoms and clinical response of the patients objectively we scored the symptoms of frequency, urgency, nocturia, dysuria and suprapubic pain on a scale of 0 to 2. Nifedipine was administered as a single daily dose determined by a dose-titration test. Urinary interleukin-2 inhibitor activity, a marker of cell-mediated inflammation, was measured using a murine interleukin-2 dependent cell line. Before nifedipine therapy the symptom scores (total of the 5 symptoms) ranged between 5 and 9, and after 2 months they ranged between 0 and 6. Of the 9 patients followed for at least 4 months only 1 failed to have a significant clinical improvement, 5 showed at least a 50% decrease in symptom scores and 3 were asymptomatic. Drug side effects were minimal. Urinary interleukin-2 inhibitor activity before nifedipine therapy confirmed the presence of cell-mediated inflammation. After 4 months of therapy interleukin-2 inhibitor activity was normal in 7 of 9 patients regardless of the severity of symptoms, which indicated that nifedipine exerted an immunosuppressive effect. Although our data suggest that nifedipine is an efficacious, well tolerated, convenient oral medication for the treatment of interstitial cystitis, the true value of nifedipine for patients with this disease must be determined by a prospective, randomized trial of nifedipine versus placebo.