Table 6.

Historical techniques previously used to evaluate the effect of drugs on platelets

Test	Description of methods
Patch test	Topical application of the drug to the patient’s skin. The test was considered positive if local purpura developed [52].
Antiglobulin consumption assay (serum bindable IgG)	A fixed amount of antiglobulin was incubated with test platelets. Residual antiglobulin was measured by complement lysis of IgG-coated erythrocytes or by quantification of radiolabeled antiglobulin bound to IgG-coated beads [53].
Platelet factor 3 (PF3) test (“immune injury” test)	Normal citrated platelet rich plasma was incubated with drug and patient serum. Increased PF3 activity, indicated by a shortening of the Russell’s viper venom (Stypven) time, was considered positive [54]. This assay was refined with a neutralization [55] or IgG isolation step [56].
Clot retraction inhibition test	Visual inspection of a blood clot formed in solution in the presence of test serum with and without drug. Inhibition of clot retraction was considered positive indicating the lack of functional platelets as a result of antibody interference [57].
Complement fixation test	Incubation of patient serum, drug, test platelets and a source of complement. Residual complement activity was measured by lysis of IgG-sensitized sheep red blood cells [58].
Platelet agglutination test	Patient serum was incubated with test platelets in the presence of the drug. Clumping in the test tube was assessed visually and graded semi-quantitatively from 0–4 after a 2-hour incubation at 37°C [59].
Platelet lysis test	51Cr-labeled platelets were incubated with test serum (or IgG), normal platelets, and a source of complement with and without drug. Percentage platelet lysis was calculated [60,61].