Drugs List

Therapeutic Indications

Uses

Local anaesthetic for infiltration anaesthesia and nerve blocks.

Administration

For administration by slow perineural injection.

Careful aspiration before and during injection is recommended to prevent intravascular administration. Accidental intravascular injection may cause toxic reactions. Careful monitoring for toxic effects is necessary during the first 30 minutes after injection. If toxic symptoms occur, the injection should be stopped immediately. When performing major blocks, an intravenous cannula should be inserted before the local anaesthetic is administered.

The main dose should be injected slowly at a rate of 100-200mg/min or in incremental doses. Note that as this formulation contains preservative, the maximum dose is 15 ml (150mg).

Contraindications

Anaemia
Congenital or acquired methaemoglobinaemia
Children under 6 months
Complete cardiac block

Prilocaine is contrindicated for paracervical block or pudendal block in obstetric patients.

Precautions and Warnings

Procedures should always be performed in a properly equipped and staffed area. Equipment and drugs required for monitoring and resuscitation should be immediately available. When performing major blocks, an intravenous cannula should be inserted before the local anaesthetic is administered. The clinician should be appropriately trained and familiar with the diagnosis and treatment of adverse effects, systemic toxicity, and other complications.

If signs of acute system toxicity appear, injections of prilocaine should be stopped immediately. In children, early signs of local anaesthetic toxicity may be difficult to detect in cases where the block is given during general anaesthesia. CNS symptoms and cardiac symptoms (e.g. cardiac failure, depression or acidosis) should be treated immediately. Acidosis, hyperkalaemia, hypercalcaemia and hypoxia increase and extend the toxic effects of local anaesthetics.

For perineural administration only. Great caution must be exercised to avoid intravascular administration as this may cause the rapid onset of toxicity with marked restlessness, twitching or convulsions. These symptoms may be followed by coma with apnoea and cardiovascular collapse. Injections into the head and neck regions may be made inadvertently into an artery, causing cerebral symptoms even at low doses. Peribulbar injections carry a low risk of persistent ocular muscle impairment. Primary causes include trauma and/or local toxic effects on the muscles or nerves.

Prilocaine must be used with caution in the following patients if the dose or site of administration is likely to result in high blood levels of prilocaine:
Elderly (reduce dose)
Epilepsy
Severe or untreated hypertension
Impaired cardiac conduction
Severe heart disease
Respiratory impairment
Renal impairment
Hepatic impairment

Use with caution in patients with myasthenia gravis , shock, hypovolaemia or in debilitated patients (reduce dose).

Methaemoglobinaemia my occur after the administration of prilocaine. Methaemoglobinaemia can be treated with an intravenous injection of methylthioninium chloride 1%. Infants are particularly susceptible, due to a lower activity of the enzyme which reduces methaemoglobin to haemoglobin. Also, there is an increased risk of methaemoglobin formation in the neonate after delivery. Thus, prilocaine is not recommended for paracervical block (PCB) or pudendal block in obstetric patients or in children under 6 months.
The repeated administration of prilocaine, even in relatively small doses, can lead to clinically overt methaemoglobinaemia (cyanosis). If this is observed, it is important to rule out other more serious causes of cyanosis such as acute hypoxaemia and/or heart failure. Prilocaine is not recommended for continuous techniques of regional anaesthesia.

Pregnancy - see Pregnancy section
Breastfeeding - see Lactation section

Administration into inflamed or infected tissues should be avoided, as increased absorption into the blood can result in increased systemic effects. The local anaesthetic effect may be reduced by the altered local pH of such tissues.

Local anaesthetics may have a very mild effect on mental function, which may impair locomotion, co-ordination and consequently affect the ability to drive and operate machinery. A doctor should decide if a patient is able to drive or operate machinery.

Patients treated with anti-arrhythmic drugs class III should be closely monitored and ECG should be considered since cardiac effects may be additive.

Multidose solutions contain preservative and should therefore 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.

There have been post-marketing reports of chondrolysis (mostly in the shoulder) in patients receiving post-operative intra-articular continuous infusion of local anaesthetics. Causality has not been established. Prilocaine 1% is not approved for this indication.

Local anaesthetics can cause ototoxicity - do not apply to the middle ear.

Contains hydroxybenzoate.

Use in Porphyria

The manufacturer advises that prilocaine solution for injection is possibly porphyric and should only be prescribed to patients with acute porphyria when no safer alternative is available. However, the Norwegian Porphyria Centre (NAPOS) classifies prilocaine as being 'not porphrinogenic' and as such no precautions are needed.

Pregnancy and Lactation

Pregnancy

Prilocaine should not be given in pregnancy unless the benefits outweigh the possible risks.

There is no adequate data from the use of prilocaine in pregnant women. Prilocaine can cross the placenta. Prilocaine in contraindicated for use for paracervical block or pudendal block in the obstetric patient as neonatal methaemoglobinaemia has been reported. There is an increased risk of high or total spinal block in patients in the final period of pregnancy - a reduced dose is advised. Foetal adverse effects due to local anaesthetics, such as foetal bradycardia, seem to be most apparent in paracervical block anaesthesia. Such effects may be due to high concentrations of anaesthetic reaching the foetus.

Studies in animals have shown reproductive toxicity.

The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Lactation

Prilocaine enters breast milk but at recommended doses there is no risk of adverse effects to the infant.

Information from LactMed states that based on the low excretion of other local anaesthetics into breast milk, a single dose of prilocaine injected during breastfeeding, such as for a dental procedure, is unlikely to adversely affect the breastfed infant. However, an alternative drug may be preferred, especially while nursing a newborn or preterm infant. Schaefer recommends avoiding use of prilocaine in breastfeeding women however there is no need to interrupt breastfeeding if used accidentally.

Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1

Drug substance licensed in infants? - No. Contraindicated in children under 6 months.

Side Effects

CNS toxicity
Dizziness
Paraesthesia
Nausea
Vomiting
Tremor
Convulsions
Unconsciousness
Respiratory depression
Cardiovascular effects
Hypotension
Hypertension
Bradycardia
Cardiac arrest
Cardiac arrhythmias
Allergic reaction
Urticaria
Oedema
Anaphylaxis
Dyspnoea
Nerve damage
Neuropathy
Diplopia
Methaemoglobinaemia
Cyanosis
Tongue numbness
Lightheadedness
Hyperacusis
Tinnitus
Visual disturbances
Dysarthria
Muscle twitch
Grand mal seizure
Hypoxia
Apnoea
Feeling drunk
Sedation
Mouth numbness
Restlessness
Feeling hot
Sensation of cold
Excitation
Myocardial depression
Depression
Drowsiness
Coma
Peripheral vasodilatation
Nervousness
Blurred vision
Respiratory failure
Hypercapnia
CNS effects

Presentation

Solution for injection containing prilocaine hydrochloride 10mg/ml (1%).

Drugs List

Therapeutic Indications

Uses

Local anaesthetic for infiltration anaesthesia and nerve blocks.

Dosage

This monograph relates only to the slow perineural injection of prilocaine.
A different strength of prilocaine for spinal anaesthesia is available and the separate monograph should be consulted for further information.

The dosage should be adjusted according to the response of the patient and the site of administration.

Dosage also depends on the vascularity of the tissues, duration of administration and the technique used. The maximum dose must be determined by evaluating the size and physical status of the patient, including age, weight, physique and clinical condition. In determining the safe dosage, it is also important to take into account the rate of absorption/excretion, and of the potency

The lowest concentration and smallest dose to produce the desired effect should be used.

To avoid excess dosage in obese patients, dose may need to be calculated on the basis of ideal body weight.

Adults

Elderly

Children

Patients with Renal Impairment

Patients with Hepatic Impairment

Additional Dosage Information

Administration

For administration by slow perineural injection.

Careful aspiration before and during injection is recommended to prevent intravascular administration. Accidental intravascular injection may cause toxic reactions. Careful monitoring for toxic effects is necessary during the first 30 minutes after injection. If toxic symptoms occur, the injection should be stopped immediately. When performing major blocks, an intravenous cannula should be inserted before the local anaesthetic is administered.

The main dose should be injected slowly at a rate of 100-200mg/min or in incremental doses. Note that as this formulation contains preservative, the maximum dose is 15 ml (150mg).

Contraindications

Anaemia
Congenital or acquired methaemoglobinaemia
Children under 6 months
Complete cardiac block

Prilocaine is contrindicated for paracervical block or pudendal block in obstetric patients.

Precautions and Warnings

Procedures should always be performed in a properly equipped and staffed area. Equipment and drugs required for monitoring and resuscitation should be immediately available. When performing major blocks, an intravenous cannula should be inserted before the local anaesthetic is administered. The clinician should be appropriately trained and familiar with the diagnosis and treatment of adverse effects, systemic toxicity, and other complications.

If signs of acute system toxicity appear, injections of prilocaine should be stopped immediately. In children, early signs of local anaesthetic toxicity may be difficult to detect in cases where the block is given during general anaesthesia. CNS symptoms and cardiac symptoms (e.g. cardiac failure, depression or acidosis) should be treated immediately. Acidosis, hyperkalaemia, hypercalcaemia and hypoxia increase and extend the toxic effects of local anaesthetics.

For perineural administration only. Great caution must be exercised to avoid intravascular administration as this may cause the rapid onset of toxicity with marked restlessness, twitching or convulsions. These symptoms may be followed by coma with apnoea and cardiovascular collapse. Injections into the head and neck regions may be made inadvertently into an artery, causing cerebral symptoms even at low doses. Peribulbar injections carry a low risk of persistent ocular muscle impairment. Primary causes include trauma and/or local toxic effects on the muscles or nerves.

Prilocaine must be used with caution in the following patients if the dose or site of administration is likely to result in high blood levels of prilocaine:
Elderly (reduce dose)
Epilepsy
Severe or untreated hypertension
Impaired cardiac conduction
Severe heart disease
Respiratory impairment
Renal impairment
Hepatic impairment

Use with caution in patients with myasthenia gravis , shock, hypovolaemia or in debilitated patients (reduce dose).

Methaemoglobinaemia my occur after the administration of prilocaine. Methaemoglobinaemia can be treated with an intravenous injection of methylthioninium chloride 1%. Infants are particularly susceptible, due to a lower activity of the enzyme which reduces methaemoglobin to haemoglobin. Also, there is an increased risk of methaemoglobin formation in the neonate after delivery. Thus, prilocaine is not recommended for paracervical block (PCB) or pudendal block in obstetric patients or in children under 6 months.
The repeated administration of prilocaine, even in relatively small doses, can lead to clinically overt methaemoglobinaemia (cyanosis). If this is observed, it is important to rule out other more serious causes of cyanosis such as acute hypoxaemia and/or heart failure. Prilocaine is not recommended for continuous techniques of regional anaesthesia.

Pregnancy - see Pregnancy section
Breastfeeding - see Lactation section

Administration into inflamed or infected tissues should be avoided, as increased absorption into the blood can result in increased systemic effects. The local anaesthetic effect may be reduced by the altered local pH of such tissues.

Local anaesthetics may have a very mild effect on mental function, which may impair locomotion, co-ordination and consequently affect the ability to drive and operate machinery. A doctor should decide if a patient is able to drive or operate machinery.

Patients treated with anti-arrhythmic drugs class III should be closely monitored and ECG should be considered since cardiac effects may be additive.

Multidose solutions contain preservative and should therefore 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.

There have been post-marketing reports of chondrolysis (mostly in the shoulder) in patients receiving post-operative intra-articular continuous infusion of local anaesthetics. Causality has not been established. Prilocaine 1% is not approved for this indication.

Local anaesthetics can cause ototoxicity - do not apply to the middle ear.

Contains hydroxybenzoate.

Use in Porphyria

The manufacturer advises that prilocaine solution for injection is possibly porphyric and should only be prescribed to patients with acute porphyria when no safer alternative is available. However, the Norwegian Porphyria Centre (NAPOS) classifies prilocaine as being 'not porphrinogenic' and as such no precautions are needed.

Pregnancy and Lactation

Pregnancy

Prilocaine should not be given in pregnancy unless the benefits outweigh the possible risks.

There is no adequate data from the use of prilocaine in pregnant women. Prilocaine can cross the placenta. Prilocaine in contraindicated for use for paracervical block or pudendal block in the obstetric patient as neonatal methaemoglobinaemia has been reported. There is an increased risk of high or total spinal block in patients in the final period of pregnancy - a reduced dose is advised. Foetal adverse effects due to local anaesthetics, such as foetal bradycardia, seem to be most apparent in paracervical block anaesthesia. Such effects may be due to high concentrations of anaesthetic reaching the foetus.

Studies in animals have shown reproductive toxicity.

The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Lactation

Prilocaine enters breast milk but at recommended doses there is no risk of adverse effects to the infant.

Information from LactMed states that based on the low excretion of other local anaesthetics into breast milk, a single dose of prilocaine injected during breastfeeding, such as for a dental procedure, is unlikely to adversely affect the breastfed infant. However, an alternative drug may be preferred, especially while nursing a newborn or preterm infant. Schaefer recommends avoiding use of prilocaine in breastfeeding women however there is no need to interrupt breastfeeding if used accidentally.

Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1

Drug substance licensed in infants? - No. Contraindicated in children under 6 months.

Effects on Ability to Drive and Operate Machinery

Local anaesthetics may have a very mild effect on mental function, which may impair locomotion, co-ordination and consequently affect the ability to drive and operate machinery. A doctor should decide if a patient is able to drive or operate machinery.

Counselling

Advise patients that their ability to drive or operate machinery may be affected following administration of prilocaine.

Side Effects

CNS toxicity
Dizziness
Paraesthesia
Nausea
Vomiting
Tremor
Convulsions
Unconsciousness
Respiratory depression
Cardiovascular effects
Hypotension
Hypertension
Bradycardia
Cardiac arrest
Cardiac arrhythmias
Allergic reaction
Urticaria
Oedema
Anaphylaxis
Dyspnoea
Nerve damage
Neuropathy
Diplopia
Methaemoglobinaemia
Cyanosis
Tongue numbness
Lightheadedness
Hyperacusis
Tinnitus
Visual disturbances
Dysarthria
Muscle twitch
Grand mal seizure
Hypoxia
Apnoea
Feeling drunk
Sedation
Mouth numbness
Restlessness
Feeling hot
Sensation of cold
Excitation
Myocardial depression
Depression
Drowsiness
Coma
Peripheral vasodilatation
Nervousness
Blurred vision
Respiratory failure
Hypercapnia
CNS effects

Overdosage

It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

The following number will direct the caller to the relevant local centre (0844) 892 0111

Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Shelf Life and Storage

Do not store above 25 degrees C.

Further Information

Last Full Review Date: March 2011

Reference Sources

Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 2nd edition (2007) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

Martindale: The Complete Drug Reference, 36th edition (2009) ed. Sweetman, S. Pharmaceutical Press, London.

Summary of Product Characteristics: Citanest 1%. AstraZeneca UK Ltd. Revised December 2010.

European Porphyria Initiative, Available at; https://www.porphyria-europe.com/index.asp
Last Revised: April, 2006.
Last accessed: February 28, 2011

NICE Evidence Services Available at: www.nice.org.uk Last accessed: 15 Septemebr 2017

The Norwegian Porphyria Centre (NAPOS). The drug database for Acute Porphyria.
Available at: https://www.drugs-porphyria.org/languages/UnitedKingdom/index.php?l=gbr
Last accessed: February 28, 2011

US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
Available at: https://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT
Prilocaine. Last revised: January 31, 2011.
Last accessed: February 27, 2011