Aim: The objective of present study was to determine Plasma Protein
Binding activity and its effect on clinical efficacy of isometamidium after
intramuscular administration in calves. The binding of drugs to plasma proteins
is an important factor in controlling the availability and distribution of
drugs. In general, PPB reduces the free fraction of drug available for
therapeutic activity, since only the non-protein bound drug is pharmacologically
active.
Materials and Methods: Six calves were used for PPB study and
eighteen for clinical efficacy. Isometamidium was administered @ 0.5mg/kg
intramuscularly as a single dose for PPB study. Equilibrium dialysis technique
was used to determine the PPB activity. For clinical efficacy, infection with
Trypanosoma was induced in calves of two groups, untreated control and
experimental group. Infection was confirmed after 28 days by mice inoculation
test. Isometamidium @ 0.5mg/kg was administered to experimental group.
Haematoobiochemical and mice inoculation tests were performed after 7 days of
drug administration (Day 35).
Result: The percentage of PPB activity of
isometamidium was 86.71 ± 0.59 to 93.03 ± 0.63% against the concentration 9.76±
0.84 to 4.39 ± 0.20 g ml-1. Higher percentage of PPB activity (>86%) suggests
greater duration of safety by this drug. It was found that anthelmintic activity
of isometamidium was substantially affected by higher PPB.
Conclusion: It
was concluded that isometamidium has greater plasma protein binding capacity
which did not hamper clinical efficacy of drug.
Keywords: anthelmintic,
calf model, plasma protein binding activity, trypanosoma
