COMPOSITION:
Each 1ml Sterile ophthalmic Solution contains 4mg Oxybuprocaine hydrochloride (0.4% w/v).
Preservative: Boric acid
MECHANISM OF ACTION:
Surface or topical anaesthesia blocks conduction of sensory, motor and autonomic nerve fibres, the excitability of nociceptors and the conducting system of the heart.
A 0.4 % solution of oxybuprocaine has been shown to give effective surface anaesthesia in short opthalmological procedures. Sensation of pain is locally and reversibly reduced, with the possibility of temperature and pressure sensitivity also affected.
Anaesthetic activity is ten times that of cocaine and twice that of tetracaine
INDICATIONS:
To produce local anaesthesia in the eye for short opthalmological procedures.
DOSAGE AND ADMINISTRATION:
-One drop of 0.4% oxybuprocaine solution instilled into each eye has been shown sufficient for tonometry after one minute. Addition of a further drop after 90 seconds provides adequate anaesthesia for fitting of a contact lens.
-To obtain a deeper anaesthetic effect, further drops may be instilled at intervals of no less than 90 seconds.
-For most procedures one to two drops is sufficient.
-For removal of foreign bodies or minor surgery, three to six drops is suggested.
-One drop a minute for 10 minutes was shown to provide adequate anaesthesia for patients undergoing pterygium surgery
CONTRAINDICATIONS:
- Known hypersensitivity to anaesthetics in this group.
- Concomitant infection of the eye.
SIDE EFFECTS:
Ocular: a transient stinging or burning sensation.
Stromal infiltration, oedema, candida keratitis, disciform keratitis and peripheral corneal ring formation have all been reported as a result of the frequent use of oxybuprocaine
Frequent or chronic use can also result in acquired tolerance, epithelial cell damage irreversible. apical cell damage at the level of the corneal endothelial cells and keratitis.
Local anaesthetics are known to inhibit the rate of movement of corneal epithelial cells migrating to cover wounds.
Reductions in tear film stability have also been documented as a result of oxybuprocaine treatment
Frequency unknown: eye allergy, allergic blepharitis
Central Nervous System: Abuse or overdose of oxybuprocaine may cause sedation, confusion, agitation, euphoria, disorientation, hearing, visual or speech disorders.
Gastrointestinal: Occasional nausea, vomiting and dysphagia have been observed during therapy.
Immunological: allergic reactions including contact allergy, urticaria and angioneurotic oedema.
Frequency unknown: hypersensitivity, anaphylactic reaction/shock.
PRECAUTIONS:
1- The anaesthetized eye should be protected from dust and bacterial contamination.
2- Systemic absorption may be reduced by compressing the lacrimal sac at the medial canthus for a minute during and following the instillation of the drops.this blocks the passage of the drops via the naso-lacrimal duct tob the wide absorptive area of the nasal and pharyngeal mucosa it is especially advisable in children.
3- This preparation may cause transient blurring of vision.patient should be advised not to drive or operate hazardous machinery until their vision is clear .
4- Oxybuprocaine has the potential to cause severe corneal damage and morbidity.
5- Hypersensitivity reactions including lung oedema.
6- Oxybuprocaine eye drops should not be used for prolonged periods. Frequent or chronic use may result in severe corneal damage, keratitis and acquired tolerance.
7- Topical ophthalmic use only.
8- No data available in elderly and Paediatric use.
PHARMACOKINETIC PROPERTIES:
Absorption: Most local anaesthetics are readily absorbed through mucous membranes and through damaged skin.
Distribution: Local anaesthetics at tissue pH can diffuse through connective tissue and cellular membranes to reach the nerve fibre where ionisation can occur.
Excretion: Urinary excretion of the drug and its metabolites at 9h after an oral dose is approximately 90%.
Metabolism Oxybuprocaine is metabolized by esterases in the plasma and, to a lesser extent, in the liver. There are at least nine metabolites, with 3-butoxy-4-aminobenzoic acid making up 70- 90 %. Their activity is unknown
Drug Interactions:
Metabolism of local anaesthetics derived from esters may be inhibited by anticholinesterases and thus prolong the effects of oxybuprocaine. Ester - type local anaesthetics may competitively enhance the neuromuscular blocking action of suxamethonium.
USE IN PREGNANCY AND LACTATION:
Safety for use in pregnancy and lactation has not been established. Oxybuprocaine eye drops should be used only when it is considered essential by a physician.
OVERDOSE:
Overdose of any local anaesthetic may cause various serious neurological, cardiovascular and respiratory events. These are overwhelmingly associated with oral and parenteral use/abuse, and are unlikely to occur in therapeutic, topical doses.
Treatment for the various clinical effects is complex, however cessation of drug and supportive management including oxygen, intravenous fluids and management of any seizures is essential .