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Effects of methaqualone on blood platelet function
Author(s) -
Mills Donald G.
Publication year - 1978
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1978236685
Subject(s) - methaqualone , diphenhydramine , chemistry , platelet , pharmacology , medicine , histamine
To study the mechanism whereby toxic doses of methaqualone cause a bleeding tendency in humans, the effects of methaqualone, diphenhydramine, and the combination of methaqualone plus diphenhydramine on blood platelet function were investigated. Exposure of human platelets in platelet‐rich plasma in vitro to final concentrations of methaqualone ranging from 1.1 to 4.5 × 10 −4 M resulted in nearly complete inhibition of the secondary phase and significant inhibition of the primary phase of adenosine diphosphate (ADP)‐induced aggregation. Both the slope and height of collagen‐induced aggregation responses were reduced significantly in vitro by the drug. When methaqualone final concentrations of 1.1, 2.3, and 4.5 × 10 −4 M were studied in the presence of diphenhydramine (1.1, 2.3, and 4.5 × 10 −5 M, respectively), the degree of inhibition of ADP‐induced aggregation was only slightly greater (not significant) than that observed with methaqualone. The platelets of rabbits injected intravenously with methaqualone, 10 mg/kg, demonstrated a significantly decreased ability to aggregate with ADP and collagen 30 and 60 min after administration of the drug. These results suggest that a drug‐induced defect of blood platelet function may play a role in the bleeding associated with methaqualone toxicity.