Note on lewisite – properties , mechanism of action and clinical effects and clinical diagnosis.

Lewisite is a potent vesicant and arsenical chemical warfare agent with the chemical formula C2H2AsCl3. It exists as a colorless to brownish-yellow oily liquid at room temperature and has a garlic-like odor. Lewisite is highly toxic and causes severe skin, eye, and respiratory tract damage upon exposure.

Mechanism of Action:
Lewisite exerts its toxic effects by alkylating sulfhydryl groups on proteins, leading to tissue damage and inflammation. It primarily targets the skin, eyes, and respiratory tract, causing blistering, ulceration, and necrosis. Additionally, Lewisite can inhibit enzymes involved in cellular metabolism, disrupt cellular functions, and induce oxidative stress, contributing to its cytotoxic effects.

Clinical Effects:
Exposure to Lewisite results in a range of acute symptoms, including skin irritation, blistering, and burns upon contact with the skin. Ocular exposure causes severe eye pain, conjunctivitis, corneal damage, and potentially irreversible blindness. Inhalation of Lewisite vapor or aerosols leads to respiratory symptoms such as coughing, chest tightness, dyspnea, and pulmonary edema, which can progress to respiratory failure and death if left untreated. Systemic effects may include nausea, vomiting, abdominal pain, and neurological symptoms.

Clinical Diagnosis:
Diagnosis of Lewisite exposure is based on clinical presentation, history of exposure to chemical agents, and laboratory tests. Skin and eye examination may reveal characteristic signs of vesicant exposure, including blistering, erythema, and ulceration. Pulmonary symptoms such as cough, dyspnea, and chest auscultation findings may suggest respiratory tract involvement. Laboratory tests may include blood gas analysis, chest X-ray, and measurement of blood arsenic levels. Prompt diagnosis and initiation of treatment are essential to mitigate the effects of Lewisite exposure and prevent complications.

Overall, Lewisite is a highly toxic chemical warfare agent that causes severe skin, eye, and respiratory tract damage. Effective management of Lewisite exposure requires rapid decontamination, supportive care, and administration of specific antidotes such as British Anti-Lewisite (BAL) to minimize morbidity and mortality.