Chemical formula: C₁₆H₂₆N₂O₃ Molecular mass: 294.389 g/mol PubChem compound: 4935
Proxymetacaine is a potent topical anaesthetic of the ester type.
The main site of anaesthetic action is the nerve cell membrane where proxymetacaine interferes with the large transient increase in the membrane permeability to sodium ions that is normally produced by a slight depolarisation of the membrane. As the anaesthetic action progressively develops in a nerve, the threshold for electrical stimulation gradually increases and the safety factor for conduction decreases; when this action is sufficiently well developed, block of conduction is produced.
The exact mechanism whereby proxymetacaine and other local anaesthetics influence the permeability of the cell membrane is unknown; however, several studies indicate that local anaesthetics may limit sodium ion permeability through the lipid layer of the nerve cell membrane. This limitation prevents the fundamental change necessary for the generation of the action potential.
Proxymetacaine, in common with other local anaesthetics, reversibly blocks the initiation and conduction of nerve impulses by decreasing the permeability of the neuronal membrane to sodium ions.
The delay to onset of effect, duration of effect and potency of proxymetacaine are similar to those of amethocaine.
Proxymetacaine is a rapid acting local anaesthetic suitable for ophthalmic use. With a single drop, the onset of anaesthesia usually begins within 30 seconds and persists for 15 minutes or longer. Proxymetacaine is a potent topical anaesthetic of the ester type.
Proxymetacaine is readily absorbed into the systemic circulation where, in common with other ester-type local anaesthetics, it is hydrolysed by plasma esterases; however, high doses can cause undesirable systemic effects. Proxymetacaine is also subject to hepatic metabolism.
No adverse safety issues were identified during the development of this formulation. The ingredients are well established in clinical ophthalmology.
The carcinogenic potential of proxymetacaine has not been investigated in long-term animal studies.
No study has been conducted to determine the potential mutagenicity of proxymetacaine.
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