New Zealand - English - Medsafe (Medicines Safety Authority)
NEW ZEALAND DATA SHEET
1. PRODUCT NAME
solution for injection
Prilocaine hydrochloride 0.5%, 2.0%
2. QUALITATIVE AND QUANTITATIVE COMPOSITION
Citanest contains 5mg or 20mg of prilocaine hydrochloride per 1mL
For full list of excipients, see section 6.1
3. PHARMACEUTICAL FORM
Citanest solution for injection is a sterile, isotonic aqueous solution. The pH of the
solution is 5.0-7.0. The single dose vials and Polyamps® are free from preservatives
and are intended for single use only.
4. CLINICAL PARTICULARS
Citanest solutions are indicated for the production of local or regional anaesthesia by
the following techniques:
minor and major nerve blocks
intravenous regional anaesthesia.
Dose and method of administration
Care should be taken to prevent toxic reactions by avoiding intravascular injection.
Careful aspiration before and during the injection is recommended. When a large
dose is to be injected, e.g. in epidural block, a test dose of 3-5 mL of prilocaine
containing adrenaline is recommended. An accidental intravascular injection may be
recognised by a temporary increase in heart rate. The main dose should be injected
slowly, at a rate of 100-200 mg/min, or in incremental doses, while keeping in
constant verbal contact with the patient. If toxic symptoms occur, the injection
should be stopped immediately.
In general, surgical anaesthesia (e.g. epidural administration) requires the use of the
higher concentrations and doses. When a less intense block is required, the use of
a lower concentration is indicated. The volume of local anaesthetic used will affect
the extent of spread of anaesthesia.
anaesthetic may be injected, can be used. This technique is common in epidural
anaesthesia and may also be used in brachial plexus anaesthesia and interpleural
The following table is a guide to dosage for the more commonly used techniques in
the average adult. The figures reflect the expected average dose range needed.
techniques and for individual patient requirements.
The clinician´s experience and knowledge of the patient´s physical status are of
importance in calculating the required dose. The lowest dose required for adequate
anaesthesia should be used (see Special warnings and precautions for use).
Individual variations in onset and duration occur.
Table 1 - Dosage Recommendations.
Type of block
Surgical operations and
Surgical operations and
IV Regional (Bier´s block)
i). thigh tourniquet
ii). calf tourniquet
- " -
- " –
Arthroscopy and surgical
- " -
Field block (eg minor nerve
blocks and infiltration
- " -
Intercostal (per nerve)
Postoperative pain and
- " -
Major Nerve Block
Supraclavicular, interscalene and
3 in 1 (Femoral, obturator and
a) Dose includes test dose
b) Do not deflate tourniquet within 20 min of injection
c) There have been post marketing reports of chondrolysis in patients receiving post-operative intra-articular
continuous infusion of local anaesthetics. C
is not approved for this indication (Also see Special warnings
and precautions for use).
= up to
NR = not recommended
The doses in Table 2 should be regarded as guidelines for use in paediatrics.
Individual variations occur. In children with a high body weight a gradual reduction of
the dosage is often necessary and should be based on the ideal body weight.
techniques and for individual patient requirements.
Table 2 - Dosage Recommendations in Children.
Type of block
(children above the age of 6 months)
Consider both age and weight for calculation of dosages.
Prilocaine for injection is not recommended in children under 6 months of age or 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
A reduction in dosage may be necessary for elderly patients, especially those with
compromised cardiovascular and/ or hepatic function.
In epidural anaesthesia a smaller dose may provide adequate anaesthesia.
WITH IMPAIRED HEPATIC FUNCTION
Although prilocaine is partly metabolised by the liver, dosage reduction is probably
not warranted. However, caution should be exercised with repeated doses.
WITH IMPAIRED RENAL FUNCTION
Impairment of renal function is unlikely to affect prilocaine clearance in the short-term
(24 hours). However toxicity due to accumulation may develop with prolonged or
Prilocaine solutions are contraindicated in patients with known hypersensitivity to
local anaesthetics of the amide type or any of the excipients.
Prilocaine solutions are contraindicated in patients with congenital or idiopathic
Special warnings and precautions for use
Regional anaesthetic procedures should always be performed in a properly equipped
emergency resuscitation should be immediately available. When performing major
blocks or using large doses, an IV cannula should be inserted before the local
anaesthetic is injected. Clinicians should have received adequate and appropriate
training in the procedure to be performed and should be familiar with the diagnosis
Although regional anaesthesia is frequently the optimal anaesthetic technique, some
patients require special attention to reduce the risk of dangerous side effects:
The elderly and patients in poor general condition.
anaesthetics may depress myocardial conduction.
Patients with advanced liver disease or severe renal dysfunction.
In patients with severe anaemia or cardiac insufficiency the risk of developing
methaemoglobinaemia should be considered (see Undesirable effects).
Patients treated with anti-arrhythmic drugs class III (e.g. amiodarone) should be
under close surveillance and ECG monitoring considered, since cardiac effects
may be additive (see Interaction with other medicines and other forms of
Patients with acute porphyria. Prilocaine 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 the case of vulnerable
Patients with severe bradycardia, cardiac conduction disturbances or severe
Prilocaine is not recommended for use in children below the age of 6 months.
Prilocaine is not recommended for use in obstetric patients under paracervical block
(PCB) or pudendal block due to the risk of methaemoglobinaemia (see Fertility,
pregnancy and lactation, and Undesirable effects).
Certain local anaesthetic procedures may be associated with serious adverse
reactions, regardless of the local anaesthetic used, for example
Central nerve blocks may cause cardiovascular depression, especially in the
presence of hypovolaemia. Epidural anaesthesia should be used with caution in
patients with impaired cardiovascular function.
Retrobulbar injections may (very occasionally) reach the cranial subarachnoid
convulsions etc. These must be diagnosed and treated promptly.
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. Vasoconstrictors and other
Injections in the head and neck regions may be made inadvertently into an
artery, causing cerebral symptoms even at low doses.
Paracervical block can sometimes cause foetal bradycardia/tachycardia, and
careful monitoring of the foetal heart rate is necessary.
Patients with pre-existing abnormal neurological conditions.
There have been post-marketing reports of chondrolysis in patients receiving
majority of reported cases of chondrolysis have involved the shoulder joint. Due
regarding mechanism of action, causality has not been established. Intra-
articular continuous infusion is not an approved indication for C
Epidural anaesthesia may lead to hypotension and bradycardia. This risk of such
effects can be reduced, e.g., by injecting vasopressor. Hypotension should be
treated promptly with an intravenous sympathomimetic repeated as necessary.
Interaction with other medicines and other forms of interaction
Prilocaine should be used with caution in patients receiving other local anaesthetics
or agents structurally related to amide-type local anaesthetics e.g. certain anti-
arrhythmic drugs such as lignocaine, mexiletine and tocainide, since the toxic effects
could be additive. Specific interaction studies with prilocaine and anti-arrhythmic
drugs class III (e.g. amiodarone) have not been performed, but caution is advised
(see Special warnings and precautions for use).
Prilocaine in high doses may cause an increase in the methaemoglobin level,
sulphonamides, antimalarials and certain nitric compounds.
Fertility, pregnancy and lactation
Although prilocaine is indicated for anaesthesia in obstetrics there is no information
on use of prilocaine in early pregnancy. Therefore, with the exception of its use in
obstetrics, prilocaine should not be used in pregnant women, or those likely to
become pregnant, unless the expected benefit outweighs any potential risk.
When used for obstetric anaesthesia in doses over 600 mg, clinically apparent
Neonatal methaemoglobinaemia has been reported after paracervical block (PCB) or
pudendal block in the obstetric patient.
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.
It is not known to what degree prilocaine is excreted in breast milk. However, the
amounts of prilocaine reaching the infant can be assumed to be very small.
Effects on ability to drive and use machines
Besides the direct anaesthetic effect, local anaesthetics may have a very mild effect
on mental function and co-ordination even in the absence of overt CNS toxicity, and
may temporarily impair locomotion and alertness.
The adverse reaction profile for C
is similar to those of other amide local
anaesthetics. Adverse reactions caused by the drug per se are difficult to distinguish
from the physiological effects of the nerve block (e.g. decrease in blood pressure,
bradycardia), events caused directly (e.g. nerve trauma) or indirectly (e.g. epidural
abscess) by the needle puncture.
Table 3 Table of Adverse Drug Reactions (ADR)
Adverse Drug Reaction
Very Common: >1/10
Vascular disorders: hypotension *
Gastrointestinal disorders: nausea *
Gastrointestinal disorders: vomiting *
Nervous system disorders: paraesthesia, dizziness
Cardiac disorders: bradycardia
Nervous system disorders: signs and symptoms of CNS
toxicity (convulsions, paraesthesia circumoral, numbness
of the tongue, hyperacusis, visual disturbances, tremor,
tinnitus, dysarthria, loss of consciousness)
Vascular disorders: hypertension
Cardiac disorders: cardiac arrest, cardiac arrhythmias
Immune system disorders: allergic reactions, anaphylactic
Respiratory disorders: respiratory depression
Nervous system disorders: neuropathy, peripheral nerve
Blood and lymphatic system disorders:
methaemoglobinaemia (See OVERDOSE) and cyanosis.
Eye disorders: diplopia
*ADRs occur more frequently after epidural blocks.
ACUTE SYSTEMIC TOXICITY
Systemic toxic reactions primarily involve the central nervous system (CNS) and the
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
Dysarthria, muscular twitching or tremors are more serious and precede the onset of
generalized convulsions. These signs must not be mistaken for neurotic behaviour.
Unconsciousness and grand mal convulsions may follow which may last from a few
convulsions due to the increased muscular activity, together with the interference
with respiration and possible loss of functional airways. In severe cases apnoea may
occur. Acidosis, hyperkalaemia, hypocalcaemia and hypoxia increase and extend
the toxic effects of local anaesthetics.
Recovery is due to redistribution of the local anaesthetic drug from the central
nervous system and subsequent metabolism and excretion. Recovery may be rapid
unless large amounts of the drug have been injected.
Cardiovascular system toxicity may be seen in severe cases and is generally
preceded by signs of toxicity in the central nervous system. In patients under heavy
sedation or receiving a general anaesthetic, prodromal CNS symptoms may be
absent. Hypotension, bradycardia, arrhythmia and even cardiac arrest may occur as
a result of high systemic concentrations of local anaesthetics, but in rare cases
cardiac arrest has occurred without prodromal CNS effects.
In children, early signs of local anaesthetic toxicity may be difficult to detect in cases
where the block is given during general anaesthesia.
TREATMENT OF ACUTE TOXICITY
If signs of acute systemic toxicity appear, injections of the local anaesthetic should
be stopped immediately and CNS symptoms (convulsion, CNS depression) must
administration of anticonvulsant medicines.
If circulatory arrest should occur, immediate cardiopulmonary resuscitation should be
instituted. Optimal oxygenation and ventilation and circulatory support as well as
treatment of acidosis are of vital importance.
treatment with intravenous fluids, vasopressor, chronotropic and or inotropic agents
should be considered. Children should be given doses commensurate with age and
repeated administration of prilocaine, even in relatively small doses, can lead to
recommended for continuous techniques of regional anaesthesia.
The conversion of haemoglobin to methaemoglobin is caused by the prilocaine
metabolite, orthotoluidine, which has a long half-life and tends to accumulate, and in
turn, is converted to 4- and 6-hydroxytoluidine. Methaemoglobin has risen to
clinically significant levels in patients receiving high doses of prilocaine. Cyanosis
occurs when the methaemoglobin concentration in the blood reaches 1-2 g/100 mL
(6-12% of the normal haemoglobin concentration). Methaemoglobin oxidises only
slowly back to haemoglobin, although this process can be greatly accelerated by the
intravenous injection of methylene blue (see below).
The reduction in oxygen-carrying capacity due to the administration of prilocaine in
symptomless. However, in severely anaemic patients it may cause hypoxaemia. It
is important to rule out other more serious causes of cyanosis such as acute
hypoxaemia and/or heart failure.
methaemoglobinaemia (see Dose and method of administration, and Special
warnings and precautions for use).
Note: Even low concentrations of methaemoglobin may interfere with pulse oximetry
readings, indicating a false low oxygen saturation.
TREATMENT OF METHAEMOGLOBINAEMIA
intravenous injection of a 1% methylene blue solution, 1 mg/kg body weight, over a
5-minute period. Cyanosis will disappear in about 15 minutes. This dose should not
be repeated as methylene blue in high concentrations acts as a haemoglobin
important. It allows continued monitoring of the benefit/risk balance of the medicine.
Healthcare professionals are asked to report any suspected adverse reactions
Accidental intravascular injections of local anaesthetics may cause immediate (within
seconds to a few minutes) systemic toxic reactions. In the event of overdose,
systemic toxicity appears later (15-60 minutes after injection) due to the slower
increase in local anaesthetic blood concentration (see Undesirable effects).
For advice on the management of overdose please contact the National Poisons
Centre on 0800 POISON (0800 764766).
5. PHARMACOLOGICAL PROPERTIES
Prilocaine hydrochloride is a local anaesthetic of the amide type. It is similar to
lignocaine in having a rapid onset and a medium duration of action. The 2% solution
will last 1½-2 h when given epidurally, and up to 4 hours with peripheral nerve
blocks. When used in concentrations of 1% there is less effect on motor nerve fibres
and the duration of action is shorter. The peak plasma concentrations of prilocaine
are lower than those associated with the same dose of lignocaine and it is also more
quickly eliminated. Prilocaine has a lower acute toxicity than lignocaine.
Onset and duration of the local anaesthetic effect of prilocaine depend on the dose
methaemoglobinaemia makes it unsatisfactory for continuous techniques.
Prilocaine, like other local anaesthetics, causes a reversible blockade of impulse
propagation along nerve fibres by preventing the inward movement of sodium ions
through the cell membrane of nerve fibres. The sodium channels of the nerve
membrane are considered a receptor for local anaesthetic molecules.
Local anaesthetics may have similar effects on other excitable membranes e.g.
brain and myocardium. If excessive amounts of local anaesthetic reach the systemic
circulation, symptoms and signs of toxicity may appear, emanating mainly from the
central nervous and cardiovascular systems.
Undesirable effects) and usually precedes the cardiovascular effects. Direct effects
of local anaesthetics on the heart include slow conduction, negative inotropism and
eventual cardiac arrest.
Indirect cardiovascular effects (hypotension, bradycardia) may occur after epidural
administration depending on the extent of the concomitant sympathetic block.
Prilocaine has a pKa of 7.89 and an N-heptane/pH 7.4 buffer partition coefficient of
0.9. Prilocaine has an octanol:water partition ratio of 25 at pH 7.4, and is 40%
protein bound (mainly to alpha-1-acid glycoprotein) in plasma.
The peak plasma concentration after prilocaine administration depends on the dose,
the route of administration, vascularity of the injection site and the concomitant
administration of vasoconstrictor agents. A linear relationship exists between the
amount of prilocaine administered and the resultant peak plasma concentration in
the dose range 200-600 mg.
The highest plasma concentrations will occur after intercostal nerve block, followed
in order of decreasing concentration by injection into the lumbar epidural space,
major nerve blocks such as brachial plexus and subcutaneous tissue.
The higher concentrations following intercostal administration may be related to the
multiple injections required for this technique, whereby the solution is exposed to a
greater vascular area, which results in a greater rate of absorption. On the other
hand, the large amount of adipose tissue in the lumbar epidural space will tend to
retard vascular absorption.
Prilocaine has a mean total plasma clearance of 2.37 L/min, a large apparent
distribution volume of between 190 L and 260 L, and the terminal half-life of
prilocaine is 1.6 h.
Only a small proportion of prilocaine (less than 5%) is excreted unchanged in the
urine. In vitro and animal studies have shown metabolism of prilocaine by lung and
In the liver, prilocaine is primarly metabolized by amide hydrolysis to ortho-toluidine
and N-propylamine. Ortho-toluidine is subsequentially hydroxylated to 2-amino-3-
hydroxytoluene and 2-amino-5-hydroxytoluene, metabolites which are believed to be
responsible for the occurrence of methaemoglobinaemia.
It is uncertain to what extent disease states like severe liver cirrhosis and congestive
heart failure influence the disposition of prilocaine.
Prilocaine readily passes the placenta and free plasma concentrations are similar in
both foetus and mother. In the presence of foetal acidosis, they may be slightly
higher in the foetus, due to ion trapping. Information concerning the elimination half-
life of prilocaine in neonates is not available.
Preclincial safety data
In animal studies, the symptoms and signs of toxicity noted after high doses of
prilocaine are the results of the effects on the central nervous and cardiovascular
systems. A mild methaemoglobinaemia was seen in a single study in rats, after
repeated dosing. This is also occasionally seen in the therapeutic situation as a
result of prilocaine overdose or off-label use. No drug related adverse effects were
seen in reproduction toxicity studies, neither did prilocaine show mutagenic potential
in either in vitro or in vivo mutagenicity tests. Cancer studies have not been
performed with prilocaine, due to the area and duration of therapeutic use for this
mutagenicity tests. Cancer studies have not been performed with prilocaine due to
the indication and duration of therapeutic use of this medicine.
A metabolite of prilocaine, ortho-toluidine, showed evidence of mutagenic activity.
The metabolite ortho-toluidine has been shown to have carcinogenicity potential in
preclinical toxicological studies evaluating chronic exposure. Risk assessments
prilocaine, with the exposure used in preclinical studies, indicate a wide margin of
safety for clinical use.
6. PHARMACEUTICAL PARTICULARS
List of excipients
Sodium hydroxide (for pH adjustment)
Water for injection
consideration when alkaline solutions, i.e. carbonates are added since precipitation
Single Dose Vials
Plastic ampoules (Polyamp®)
Special precautions for storage
Store below 25
C. Do not freeze.
Nature and contents of container
0.5% 5 x 50 mL Single Dose Vials
2.0% 10 x 5 mL Polyamp® Duofit®
7. MEDICINE SCHEDULE
Pharmacy Retailing (NZ) Limited
Trading as Healthcare Logistics
58 Richard Pearse Drive
Telephone: (09) 918 5100
9. DATE OF FIRST APPROVAL
31 December 1969
DATE OF REVISION OF THE TEXT
10 November 2017
SUMMARY TABLE OF CHANGES
Summary of new information
related to epidural anaesthesia is updated.
© This data sheet is copyrighted to AstraZeneca Limited and may be reproduced but not
altered in any way.