Mannitol and the blood-labyrinth barrier

Table 1 Pharmacokinetic Parameters of Gentamicin Concentrations in Blood

Parameter	Gentamicin (ng/ml) given alone in blood (95%CI)	Gentamicin (ng/ml) with mannitol in blood (95%CI)
Y_max	184 (167–200)	172 (132–213)
k	0.045 (0.025–0.066)	0.055 (0.002–0.109)
Half life	15.27 (10.5–28.05)	12.50 (6.4–324)
tau	22.03 (15.1–40.5)	18.03 (9.2–467)
R ²	0.61	0.26

Data were fit to a first-order, decreasing exponential as eq. 1: [y(t) = y ₀ e ^−kt], to determine pharmacokinetic parameters rate constant k, and concentration at time t when t = 0 h, y₀. Fitted parameters did not differ significantly (p = 0.433) with or without mannitol so the best fit gentamicin alone is shown (n = 22 with mannitol and n = 22 without mannitol). As in Figs. 2 and 3, many data points are congruent so they look like one datum. The fitted parameters for eq. 1, (for +/− 95% confidence interval), were y₀ = 184 (+/− 167–200) ng/ml; k = 0.045(+/− 0.025–0.066) hrs⁻¹. Parameterized eq. 1 is therefore: y(t) = 184e ^−0.045t. An alternative way of expressing the rate of decay is the half-life t_1/2, which was 15.3 (+/− 10.5–28.05) hours. R² for these data was 0.61 indicating that about 61% of the variability is accounted for by the model. The finding that parameters k, and y₀ were not different with or without mannitol indicate that mannitol did not significantly affect clearance of gentamicin from blood

ISSN: 1916-0216