Plasma concentrations and ocular effects of cyclopentolate after ocular application of three formulations.
1. Eight volunteers received in randomized order two 30 microliters drops of either 1% w/v cyclopentolate hydrochloride or a corresponding amount of cyclopentolate polygalacturonate in saline or in acetate buffer in one eye. Cyclopentolate concentrations in plasma were measured by a radioreceptor assay. 2. Peak plasma drug concentrations of about 3 ng ml-1 occurred within 30 min after all formulations. Occasionally, a second concentration peak in plasma, probably reflecting drug absorption from the gastrointestinal tract, was seen after 2 h. The mean elimination half-life of cyclopentolate was 111 min when all subjects and formulations were considered together. There were no statistically significant differences between the formulations with respect to the time-course of plasma drug concentration. 3. The maximal mydriatic effect was reached within about 15 min and was maintained for several hours, often being 1/3 of its peak value after 30 h. Similarly, an intense cycloplegic response was achieved within a few minutes, the peak changes in the near-point of vision being 9 to 10 dioptres. The cycloplegic response was more intense after one of the polygalacturonate complexes, especially at later time points.
Department of Ophthalmology, University of Turku, Finland.
K
K
Lahdes
R
R
Huupponen
T
T
Kaila
D
D
Monti
M F
MF
Saettone
L
L
Salminen
D000328:Adult; D002021:Buffers; D003519:Cyclopentolate / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005079:Excipients; D005123:Eye / Q000187:drug effects*; D005260:Female; D006207:Half-Life; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009883:Ophthalmic Solutions; D010368:Pectins; D011680:Pupil / Q000187:drug effects
D002021:Buffers; D005079:Excipients; D009883:Ophthalmic Solutions; D010368:Pectins; D003519:Cyclopentolate; C003181:polygalacturonic acid