Effectiveness of Calcium Channel Blockade for OP and Carbamate Pesticide Poisoning

Inclusion Criteria:

• Patients aged 16 years or older with suspected OP or carbamate insecticideself-poisoning admitted to medical wards with the cholinergic toxidrome requiringatropine.

• Diagnosis will be made on the basis of the cholinergic toxidrome clinical features (eg. small/pinpoint pupils, bronchorrhoea, sweating) or on the history of atropineadministration with beneficial effect. The insecticide involved will be identifiedwhere possible from the history, the bottle brought in by the patient or relative,the patient/relative identifying the pesticide on a chart showing all locallyavailable pesticides, and/or relatives sending a photo of the bottle by eg.WhatsApp.

• Patients who ingest combination products containing OP or carbamate insecticideswill also be included.

• Inhibited blood cholinesterase activity as shown by routine clinical bedside test

Exclusion Criteria:

• Children aged <16 years.

• Patients who do not require atropine and have not had it prior to presentationduring this episode.

• Normal blood cholinesterase activity

• Self-reported known pregnancy (as per South Asian practice, no attempt will be madeto formally test for pregnancy in the patients due to the issue of confidentialityin the acute care situation in these hospitals and the social consequences of anunexpected positive response)

• Known occupational and homicidal poisoning

• Past medical history of severely impaired renal function

• Hypersensitivity to magnesium and its salts

• Patients who have had a myocardial infarction or unstable angina in the last month

• Patients with traumatic subarachnoid haemorrhage

• Lack of informed consent (unaccompanied unconscious patients and others)