The drug that can directly release histamine from mast cells without involving antigen-antibody reaction is:

HISTAMINE RELEASERS A variety of mechanical, chemical and immunological stimuli are capable of releasing histamine from mast cells. 1. Tissue damage: trauma, stings and venoms, proteolytic enzymes. 2. Antigen: antibody reaction involving IgE antibodies. 3. Polymers like dextran, polyvinyl pyrrolidone (PVP). 4. Some basic drugs--tubocurarine, morphine, atropine, pentamidine, polymyxin B, vancomycin and even some antihistaminics directly release histamine without an immunological reaction. 5. Surface acting agents like Tween 80, compound 48/80 etc. The primary action of these substances is release of histamine from mast cells, therefore they are called 'histamine liberators'. They produce an 'anaphylactoid' reaction--itching and burning sensation, flushing, uicaria, fall in BP, tachycardia, headache, colic and asthma. Most of these symptoms are controlled by a H1 antihistaminic, better still if H2 blocker is given together. Ref:- kd tripathi; pg num:-163