Effectiveness of calcium channel blockade for organophosphorus and carbamate pesticide poisoning – study protocol for an open label, pragmatic, 3-arm RCT repurposing two widely available medicines

The protocol for the CCBOC study. This large-scale clinical trial in Bangladesh is exploring the effectiveness of calcium channel blocking medicines (CCB) for patients with organophosphorus or carbamate poisoning.

Authors: Fazle Rabbi Chowdhurya, Suvodip Shaw, Abdullah Abu Sayeed, Soumitra Roy, Abu Shahin Mohammad Mahbubur Rahman, Nahida Zafrin, Pritish Tarafder, Muhammad Halimur Rashid, Aniruddha Ghose, Shishir Ranjan Chakraborty, Muhammad Khalilur Rahman, Muhammad Sayedur Rahman, Richard Parker, Muhammad Mahib Ullah, Zakir Hassan,Abdullah Al Mamun Sohag, Muhammad Robed Amin, Muhammad Shafiqul Bari, John Norrie, M. A. Faiz & Michael Eddleston

Published in: Toxicology Communications


Pesticide self-poisoning is one of the three most important global means of suicide, killing an estimated 110–168,000 people each year, mostly in poor rural Asian communities. Organophosphorus (OP) and carbamate anticholinesterase insecticides are responsible for about two-thirds of these deaths.

Calcium channel blocking medicines (CCB) may reduce the effect of pesticides and prevent deaths. Two preclinical rodents’ studies and eight clinical studies utilising nimodipine and magnesium sulphate (MgSO4), respectively, showed mixed results.

We have established a multi-centre randomised controlled trial (RCT) of patients with OP or carbamate self-poisoning admitted to at least six major hospitals in Bangladesh. The study aims to recruit maximum 3,243 patients over four years. One-third of the patients selected at random will receive standard treatment, while one-third will be treated with additional nimodipine and one-third with additional MgSO4. The additional treatments will be given for 48 h. We will check mortality (currently an estimated 11% die with standard treatment) and need for intensive care for mechanical ventilation across the three groups.

This could lead to development of the first novel treatment for anticholinesterase poisoning in 50 years and its introduction into routine hospital practice worldwide.