Electrochemical determination of calcium channel blocker drugs using multiwall carbon nanotube-modified glassy carbon electrode

Background: Calcium channel blockers belonging to the dihydropyridine family have been used as a potent arterial vasodilator in the management of angina and cardiovascular diseases. In the design of glassy carbon electrode coatings for the study of the same, multiwall carbon nanotubes (MWCNT) are favored. They are known for the reduction and oxidation of electroactive species towards cathodic and anodic direction with the simultaneous enhancement of the peak current. Results: The MWCNT-modified glassy carbon electrode exhibited a sharp anodic peak potential at around at 0.5 V for amlodipine (AMLD) andnimodipine (NIMD), and 0.4 V for felodipine (FELD) in the cyclic voltammograms. The antihypertensive drugs were determined using a simple two-step procedure developed which comprised a preconcentration step followed by the differential pulse stripping voltammetric quantification. Concentration calibrations were linear within the range from 0.01 to 0.3 μg/mL for AMLD and FELD, and 0.025 to 0.3 μg/mL for NIMD. Conclusion: The lower limit detection (LOD) was found to be very low on modified electrode. The LOD is 0.005 μg/mL for AMLD and FELD, and 0.01 μg/mL for NIMD. The prepared electrode showed an excellent electrocatalytic activity towards the oxidation of antihypertensive drugs leading to a remarked improvement in sensitivity. An electrochemical sensor featuring the MWCNT-modified electrode was applied successfully as the result for the calcium channel blocker determination in pharmaceutical samples.