Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1     Pharmacodynamic properties
Pharmacotherapeutic group: Ophthalmologicals; Antiglaucoma Preparation and Miotics.
ATC code: SO1E A03.

Apraclonidine is a relatively selective alpha‐2‐adrenergic agonist which does not possess significant membrane stabilising (local anaesthetic) activity. When instilled into the eye, apraclonidine has the action of reducing intraocular pressure.
Ophthalmic apraclonidine has minimal effect on cardiovascular parameters.
Aqueous fluorophotometry studies in man suggest that the mechanism of the ocular hypotensive action of apraclonidine is related to a reduction in aqueous formation.
The onset of action of IOPIDINE 0.5% Eye Drops can usually be noted within one hour and the maximum intraocular pressure reduction usually occurs three to five hours after application of a single dose.

Pharmacokinetic Properties

5.2     Pharmacokinetic properties
Following topical ocular administration to New Zealand White rabbits, apraclonidine reached peak concentrations after two hours in the aqueous humour, iris, ciliary body and lens. The cornea exhibited the greatest concentration and peaked at the earliest time point (20 minutes). The tissue distribution of apraclonidine from highest to lowest concentration in microgram equivalents per gram of tissue was cornea, iris‐ ciliary body, aqueous humour, lens and vitreous humour. The elimination half‐life of apraclonidine from the aqueous humour was determined to be approximately two hours.

Plasma concentration of apraclonidine following three times daily, bilateral, topical ocular dosing of IOPIDINE 0.5% to normal human volunteers was less than 1.0 ng/ml. A steady state level was attained after five days of dosing. The half‐life of the drug was calculated to be eight hours.