Abstract:

Hypertension is one of the well-established risk factor for cardiovascular diseases. Calcium channel blockers (CCBs), chemicals that could block voltage-gated calcium channels (VGCCs) in cardiac muscle and blood vessels, has been widely used for the treatment of hypertension. Isradipine, a second-generation CCB with high affinity for voltage-operated calcium channels, has not been marked in China. The purpose of this study was to investigate the efficacy, safety and tolerability of isradipine in a phase I clinical trial including 31 healthy Chinese subjects. All subjects received different doses of isradipine at 2.5, 5.0 and 10.0 mg in single-dose study. When the test is completed, subjects treated with 5.0 mg isradipine stayed at the research center for multiple-dose study (5.0 mg isradipine twice daily for 9 d). Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured pre-dose and post-dose (1, 2, 4, 6, 8, 12, 24, 36 and 48 h after isradipine treatment). Electrocardiography (ECG) and peripheral edema were monitored pre-dose and 4, 8, 24 and 48 h after isradipine treatment. SBP and DBP in single-dose study decreased after isradipine treatment. SBP reached the lowest values 8 h after dosing with a decrease of (7.0±9.7) mmHg (5.4%, P = 0.111) in 2.5 mg group, (7.0±6.9) mmHg (6.0%, P = 0.008) in 5.0 mg group, and (14.0±10.5) mmHg (12.7%, P = 0.005) for 10.0 mg group respectively. Similarly, DBP also reached the lowest values 8 h after dosing with a decrease of (10.0±7.9) mmHg (12.8%, P = 0.004) in 2.5 mg group, (6.0±7.0) mmHg (8.6%, P = 0.003) in 5.0 mg group, and (11.0±4.1) mmHg (15.1%, P = 0.000) in 10.0 mg group respectively. No significant changes of SBP and DBP were observed in multiple-dose study. We detected mild adverse events (AEs), such as increased transaminase and headache that resolved rapidly and spontaneously without intervention. No serious or potentially life-threatening AE was detected. Our results indicate that isradipin has a good safety and tolerability in Chinese healthy subjects. Long-term study with larger sample size is needed to confirm our conclusion.

Key words: Isradipine capsule, Tolerance, Safety, Phase I clinical trial