PRILOCAINE

Care should be taken to prevent toxic reactions by avoiding intravascular injection. Careful aspiration before and during the injection is recommended. Posology The dose is adjusted according to the response of the patient and the site of administration.

The lowest concentration and smallest dose producing the required effect should be given. The maximum dose of prilocaine hydrochloride for healthy adults should not exceed 400 mg. Older People Elderly or debilitated patients require smaller doses, commensurate with age and physical status.

Paediatric population Prilocaine hydrochloride should not be used in children under 6 months of age and for use in paracervical (PCB) block and pudendal block in the obstetric patient. There is an increased risk of methaemoglobin formation in children and in the neonate after delivery.

In children above the age of 6 months the dosage can be calculated on a weight basis up to 5 mg/kg. There have been post-marketing reports of chondrolysis in patients receiving post-operative intra-articular continuous infusion of local anaesthetics.

4). e. those supplied in multi-dose vials should not be used for intrathecal or epidural anaesthesia, intraocular or retrobulbar injections or in doses of more than 15 ml for other types of blockades.

The adverse reaction profile for prilocaine hydrochloride is similar to those of other amide local anaesthetics. g. g. g. epidural abscess) by the needle puncture. The adverse reactions considered at least possibly related to treatment with prilocaine hydrochloride from clinical trials with related products and post- marketing experience are listed below by body system organ class and absolute frequency.

Frequencies are defined as ‘very common’ (≥1/10), ‘common’ (≥1/100 to <1/10), ‘uncommon’ (≥1/1,000 to <1/100), ‘rare’ (≥1/10,000 to <1/1,000), or ‘not known’ (cannot be estimated from the available data). Table of Adverse Drug Reactions (ADRs) System Organ Class Frequency Classification Adverse Drug Reaction Blood and lymphatic system disorders Rare Methaemoglobinaemia (see below), cyanosis* Immune system disorders Rare Allergic reactions (including urticaria, oedema, dyspnoea), anaphylactic reactions Nervous system disorders Common Paraesthesia, dizziness Uncommon Signs and symptoms of CNS toxicity (see below) Rare Neuropathy, peripheral nerve injury Eye disorders Not known Diplopia System Organ Class Frequency Classification Adverse Drug Reaction Cardiac disorders Common Bradycardia Rare Cardiac arrest, cardiac arrhythmias Vascular disorders Very common Hypotension** Common Hypertension Respiratory, thoracic and mediastinal disorders Not known Respiratory depression Gastrointestinal disorders Very common Nausea** Common Vomiting** * In the presence of methaemoglobinaemia.

** ADRs occur more frequently after epidural blocks. Acute systemic toxicity Systemic toxic reactions primarily involve the central nervous system (CNS) and the cardiovascular system (CVS). 4). CNS reactions are similar for all amide local anaesthetics, while cardiac reactions are more dependent on the drug, both quantitatively and qualitatively.

Central nervous system toxicity is a graded response with symptoms and signs of escalating severity. The first symptoms are circumoral paraesthesia, numbness of the tongue, light-headedness, hyperacusis, tinnitus and visual disturbances.

Regional anaesthetic procedures should always be performed in a properly equipped and staffed area, with the equipment and drugs necessary for monitoring an emergency resuscitation immediately available. v. cannula should be inserted before the local anaesthetic is injected.

9). Great caution must be exercised to avoid accidental intravascular injection of this compound, since it may give rise to the rapid onset of toxicity, with marked restlessness, twitching, or convulsions, followed by coma with apnoea and cardiovascular collapse.

Special Patient Groups In common with other local anaesthetics, prilocaine hydrochloride should be used cautiously in the elderly, patients in poor health, patients with epilepsy, severe or untreated hypertension, impaired cardiac conduction, severe heart disease, impaired respiratory function, and in patients with liver or kidney damage, if the dose or site of administration is likely to result in high blood levels.

8). g. 5). Prilocaine hydrochloride solution for injection is possibly porphyrinogenic and should only be prescribed to patients with acute porphyria when no safer alternative is available. Appropriate precautions should be taken in case of vulnerable patients.

: - Peribulbar injections of local anaesthetics carry a low risk of persistent ocular muscle dysfunction. The primary causes include trauma and/or local toxic effects on muscles and/or nerves. The severity of such tissue reactions is related to the degree of trauma, the concentration of the local anaesthetic and the duration of exposure of the tissue to the local anaesthetic.

For this reason, as with all local anaesthetics, the lowest effective concentration and dose of local anaesthetic should be used. - Injections in the head and neck regions may be made inadvertently into an artery, causing cerebral symptoms even at low doses.

g. sulphonamides, known to cause such conditions. Infants are particularly susceptible, due to a lower activity of the enzyme which reduces methaemoglobin to haemoglobin. 8). Local anaesthetics should be avoided when there is inflammation at the site of the proposed injection.

1. Hypersensitivity to methyl and/or propyl parahydroxybenzoate (methyl- /propyl paraben), or to their metabolite para-aminobenzoic acid (PABA). Formulations of prilocaine containing parabens should be avoided in patients allergic to ester local anaesthetics or its metabolite PABA.

Prilocaine hydrochloride should be avoided in patients with anaemia or congenital or acquired methaemoglobinaemia.