Topical ophthalmic atropine in horses, pharmacokinetics and effect on intestinal motility

BMC Veterinary Research

Table 1 Bootstrap estimates of structural parameters of the 2-compartment model and secondary derived parameters

	Units	Median	CV%	2.50%	97.50%
Primary structural Parameters
tvV_c	L/kg	0.646	28.03	0.314	0.803
tvV_t	L/kg	1.148	16.39	0.740	1.277
tvCl	L/kg/h	1.905	6.63	1.771	2.148
tvCl_d	L/kg/h	2.477	23.87	1.689	3.652
tvfdrop (ilogit, eye drop)	Scalar	0.781	172.66	0.196	324.616
tvfINF (ilogit, infusion)	Scalar	0.738	199.51	0.157	12.979
tvCMultStdev (residual, proportional)	Scalar	0.243	43.96	0.037	0.370
tvK_a	1/h	5.948	198.88	3.238	122.226
stdev0 (residual, additive)	μg/L	0.019	42.28	0.004	0.029
Secondary parameters
Bioavailability Drop	Scalar (0–1)	0.685	26.12	0.549	1.000
Bioavailability infusion	Scalar (0–1)	0.676	19.59	0.539	0.952
Half-life_absorption	h	0.117	53.82	0.019	0.226
Half-life_Beta (terminal phase)	h	0.798	12.77	0.603	0.889
Half-life_alpha (initial phase)	h	0.077	20.77	0.049	0.099
V_ss (steady-state volume of distribution)	L/kg	1.747	15.99	1.169	1.960
MRT (Mean residence time (IV)	h	0.884	16.16	0.617	1.050

V_c and V_t are the volume of the central and peripheral compartment, Cl is the clearance and Cl_d is the intercompartmental distribution clearance, k_a is the absorption rate constant, fdrop and finf are the ilogit of bioavailability associated to eye drops and infusion administration, respectively. CMultStdev corresponds to the proportional component of the residual error with a value of 24.3% and stdev is the additive component of the residual. All these parameters were estimated with a reasonable precision but for the two ilogit estimates. This was due to the ilogit transformation as indicated by a rather good precision of the corresponding bioavailability (68.5 and 67.6% for the eyes drop and the infusion respectively, an ilogit value higher than 3 corresponds to a near total bioavailability.

ISSN: 1746-6148