Rivaroxaban reversal with prothrombin complex concentrate or tranexamic acid in healthy volunteers.

Essentials Specific reversal agents for managing severe factor Xa inhibitor-associated bleeding are lacking. We assessed 4-factor-prothrombin complex concentrate (4F-PCC) and tranexamic acid (TXA). 4F-PCC, but not TXA, reduced the prothrombin time and increased endogenous thrombin potential. These agents may be viable options for reversal of therapeutic doses of rivaroxaban. SUMMARY: Background Oral activated factor X inhibitors such as rivaroxaban are widely used, but specific reversal agents are lacking. Although four-factor prothrombin complex concentrate (4F-PCC) and tranexamic acid (TXA) are sometimes used to manage serious bleeding, their efficacy is unknown. Prior studies in healthy subjects taking rivaroxaban revealed that 4F-PCC partially reverses the prolonged prothrombin time (PT), and fully restores the endogenous thrombin potential (ETP). The effect of TXA has not been evaluated. Methods In this double-blind, parallel-group study, 147 healthy volunteers given rivaroxaban 20 mg twice daily for 3 days were randomized after their morning dose on day 4 to receive intravenous 4F-PCC (50 IU kg-1 ), TXA (1.0 g), or saline. Standardized punch biopsies were performed at baseline and after 4F-PCC, TXA or saline administration. Reversal was assessed by measuring bleeding duration and bleeding volume at biopsy sites, and by determining the PT and ETP. Results As compared with saline, 4F-PCC partially reversed the PT and completely reversed the ETP, whereas TXA had no effect. Neither 4F-PCC nor TXA reduced bleeding duration or volume. All treatments were well tolerated, with no recorded adverse events. Conclusions Although 4F-PCC reduced the PT and increased the ETP in volunteers given supratherapeutic doses of rivaroxaban, neither 4F-PCC nor TXA influenced punch biopsy bleeding.

Fluorescent antibody responses to adenoviruses in humans.

Specific IgG, IgA, and IgM immunoglobulin antibody responses to adenovirus infections were studied by the indirect immunofluorescent technique in six pairs of human sera obtained during acute and convalescent phases of the illness. In addition, 70 single specimens of sera showing adenovirus IgG antibody from different age groups from birth to the 60th year of life were titrated for the same antibody to adenovirus types 1, 2, 3, 5, and 7, and 170 serum specimens from the same age groups were screened for specific immunoglobulin antibodies against types 1 and 5. Specific immunoglobulin antibodies lacked type specificity and in acute infections measured heterologous antibody response as well. On the other hand, IgG antibodies detected in single specimens of sera by immunofluorescence correlate with surveys of the isolation of virus from patients and neutralizing antibody studies by other workers. Fluorescent antibodies appeared in all three fractions of the immunoglobulins in acute adenovirus infections. Although this technique may be used in the diagnosis of adenovirus infections there is no advantage compared to complement-fixation testing. However, the use of sera absorbed with group antigen may have a more useful place in serological epidemiology than in diagnostic work. In five pairs of sera obtained during acute and convalescent phases of adenoviral illness and in 70 random single specimens from different age groups, "T" antibodies were detected only in the IgG fraction. The paired sera did not show a significant rise to indicate the usefulness of "T" antibody study in diagnosis.