Prophylactic medications for anti-venom anaphylaxis
Adrenaline prophylaxis prior to snake bite anti-venom may reduce anaphylaxis and not be associated with significant adverse effects, though it is difficult to generalise as there are a variety of anti-venoms and only a small amount of evidence was identified. Two trials in children and adults in Asia found that low dose prophylactic adrenaline 0.25ml (1:1000) injected subcutaneously reduced the absolute risk of severe reactions to anti-venom without significant adverse effects (see Table 4, low certainty, supplement S7a).11Premawardhena AP, de Silva CE, Fonseka MM, Gunatilake SB, de Silva HJ. Low dose subcutaneous adrenaline to prevent acute adverse reactions to antivenom serum in people bitten by snakes: randomised, placebo controlled trial. BMJ 1999;318(7190):1041-1043.,22de Silva HA, Pathmeswaran A, Ranasinha CD, Jayamanne S, Samarakoon SB, Hittharage A, Kalupahana R, Ratnatilaka GA, Uluwatthage W, Aronson JK, Armitage JM, Lalloo DG, de Silva HJ. Low-dose adrenaline, promethazine, and hydrocortisone in the prevention of acute adverse reactions to antivenom following snakebite: a randomised, double-blind, placebo-controlled trial. PLoS Med 2011;8(5):e1000435.
It is unclear whether prophylactic intravenous corticosteroids or histamine receptor blockers reduce anaphylaxis resulting from anti-venom for snake bite because the certainty of evidence is very low. Two trials in children and adults in Asia found that hydrocortisone alone or with chlorpheniramine did not reduce the incidence of moderate to severe reactions. (low certainty, supplement S7b).33de Silva HA, Pathmeswaran A, Ranasinha CD, Jayamanne S, Samarakoon SB, Hittharage A, Kalupahana R, Ratnatilaka GA, Uluwatthage W, Aronson JK, Armitage JM, Lalloo DG, de Silva HJ. Low-dose adrenaline, promethazine, and hydrocortisone in the prevention of acute adverse reactions to antivenom following snakebite: a randomised, double-blind, placebo-controlled trial. PLoS Med 2011;8(5):e1000435.,44Gawarammana IB, Kularatne SA, Dissanayake WP, Kumarasiri RP, Senanayake N, Ariyasena H. Parallel infusion of hydrocortisone +/- chlorpheniramine bolus injection to prevent acute adverse reactions to antivenom for snakebites. Med J Aust 2004;180(1):20-23.
Two trials in children and adults found that the antihistamine promethazine did not reduce the incidence of anaphylaxis within 24 to 48 hours of antivenom (very low certainty, supplement S7c)55de Silva HA, Pathmeswaran A, Ranasinha CD, Jayamanne S, Samarakoon SB, Hittharage A, Kalupahana R, Ratnatilaka GA, Uluwatthage W, Aronson JK, Armitage JM, Lalloo DG, de Silva HJ. Low-dose adrenaline, promethazine, and hydrocortisone in the prevention of acute adverse reactions to antivenom following snakebite: a randomised, double-blind, placebo-controlled trial. PLoS Med 2011;8(5):e1000435.,66Fan HW, Marcopito LF, Cardoso JL, França FO, Malaque CM, Ferrari RA, Theakston RD, Warrell DA. Sequential randomised and double blind trial of promethazine prophylaxis against early anaphylactic reactions to antivenom for bothrops snake bites. BMJ 1999;318(7196):1451-1452.