The optimal dose of disease-specific antibodies for post-exposure prophylaxis of measles and rubella in Australia: new guidelines recommended.

BACKGROUND

It is unclear whether recommended doses of intramuscular polyvalent immune globulin are optimal for both effectiveness and efficiency of disease prevention when administered post-exposure to measles and rubella.

METHODS

The peak concentration and decay of disease-specific antibodies after intramuscular dosing of polyvalent immune globulin in adults were modeled using published pharmacokinetic parameters and product disease-specific antibody concentrations. Models simulated dosing according to current Australian guidelines, then adjusted the dose in clinically relevant increments to estimate the optimal dose of disease-specific immunoglobulins for post-exposure prophylaxis of nonimmune individuals against measles and rubella. Optimal dosing assumed a target serum concentration of disease-specific antibodies of the correlate of protection plus a 10% margin of error at an incubation period.

RESULTS

Current Australian guidelines appeared to underdose a measles-naïve subpopulation. The optimal dose of measles-specific antibodies was 17.5 IU/kg assuming 75% bioavailability and 25.5 IU/kg assuming 50% bioavailability. Current Australian guidelines recommend 520 IU/kg rubella antibodies for an 80-kg individual. This model suggests that 13 IU/kg is more than sufficient.

CONCLUSIONS

The recommended dose of intramuscular polyvalent immune globulin should be increased following measles exposure and decreased following rubella exposure for recommended subgroups. These models may be adapted for use internationally.