Optimolol Mechanism of Action

Pharmacology: Pharmacodynamics: Mechanism of action: Timolol maleate is a non-selective beta-adrenergic receptor blocking agent that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anaesthetic activity. Timolol maleate combines reversibly with the beta-adrenergic receptor, and this inhibits the usual biologic response that would occur with stimulation of that receptor. This specific competitive antagonist blocks stimulation of the beta-adrenergic stimulating (agonist) activity, whether these originate from an endogenous or exogenous source. Reversal of this blockade can be accomplished by increasing the concentration of the agonist which will restore the usual biological response.
Clinical efficacy and safety: Unlike miotics, OPTIMOLOL reduces intraocular pressure (IOP) with little or no effect on accommodation or pupil size. In patients with cataracts, the inability to see around lenticular opacities when the pupil is constricted is avoided. When changing patients from miotics to OPTIMOLOL a refraction might be necessary when the effects of the miotic have passed. Diminished response after prolonged therapy with OPTIMOLOL has been reported in some patients.
Paediatric Population: There is only very limited data available on the use of timolol (0.25%, 0.5% twice daily one drop) in the paediatric population. However, available data have shown to some extent evidence that timolol in the indication of primary congenital and primary juvenile glaucoma is effective in short term treatment.
Pharmacokinetics: The onset of reduction in intraocular pressure can be detected within one-half hour after a single dose. The maximum effect occurs in one or two hours; significant lowering of IOP can be maintained for as long as 24 hours with a single dose.
Paediatric Population: As already confirmed. by adult data, 80% of each eye drop passes through the nasolacrimal system where it may be rapidly absorbed into the systemic circulation via the nasal mucosa, conjunctiva, nasolacrimal duct, oropharynx and gut, or the skin from tear overflow.
Due to the fact that the blood volume in children is smaller than that in adults a higher circulation concentration has to be taken into account. In addition, neonates have immature metabolic enzyme pathways and it may result in an increase in elimination half-life and potentiating adverse events.
Limited data show that plasma timolol levels in children after 0.25% greatly exceed those in adults after 0.5%, especially in infants and are presumed to increase the risk of side effects such as bronchospasm and bradycardia.