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Short-acting ester local anaesthetic Pregnancy: §4.6, verbatim: 'Animal studies are insufficient with respect to effects on pregnancy and foetal development (see 5.3). Therefore, Ampres is not recommended during pregnancy and in women of childbearing potential not using contraception. The use of Ampres in pregnancy should only be considered if the expected benefit to the mother outweighs any potential risk to the foetus. This does not preclude the use of Ampres at term for obstetrical anaesthesia.' Breast-feeding: 'It is not known whether chloroprocaine/metabolites are excreted in human milk. A decision must be made whether to discontinue breast-feeding or to discontinue/abstain from Ampres therapy taking into account the benefit of breast-feeding for the child and the benefit of therapy for the woman.' Fertility: 'No fertility studies have been performed.'

Chloroprocaine hydrochloride

Brand names: Ampres, Clorotekal

Chloroprocaine hydrochloride is a short-acting ester local anaesthetic used for infiltration anaesthesia and short surgical or obstetric procedures, including some neuraxial techniques.

Adult dose

Dose: Intrathecal (spinal) anaesthesia in adults: 40 mg (4 ml) to 50 mg (5 ml) of the 10 mg/ml solution, as a single intrathecal injection. §4.2: 'The indications relating to recommended doses are valid in adults of average height and weight (approximately 70 kg) for obtaining an effective block with one single administration.' Dose is individualised — 'Posology must be established on an individual basis in accordance with the characteristics of the specific case.' SCOPE — INTRATHECAL ONLY: this page also lists epidural and infiltration routes, but the Ampres SPC is licensed 'For intrathecal use' and contains no epidural, caudal, peripheral-nerve-block or infiltration regimen, so NO epidural and NO infiltration dose is published on this record.
Route: Intrathecal (spinal) injection only. §4.2 Method of administration, verbatim: 'For intrathecal use. Ampres should be injected via the intrathecal route into the intervertebral space L2/L3, L3/L4 and L4/L5. The entire dose should be injected slowly, after having aspirated a minimum quantity of CSF to confirm the correct position. The patient's vital functions should be checked extremely carefully maintaining continuous verbal contact. For single use.' §4.3 contraindicates intravenous regional anaesthesia.
Frequency: Single administration for the procedure — the quoted doses are those for 'an effective block with one single administration'. The SPC gives no repeat-dose, top-up or infusion regimen, and the product is 'For single use'.
Max: 50 mg (5 ml) — §4.2, verbatim: 'The maximum recommended dose is 50mg (=5ml) of chloroprocaine hydrochloride.'
HOW THE DOSE TABLE WAS READ: the adult dose table is flattened in the fetched text and reads, verbatim: 'Posology Adults Extension of sensory blockade required T10 ml mg Average duration of action (minutes) 4 5 40 50 80 100'. The ml-to-mg pairing is fixed by the product strength (Ampres is 10 mg/ml) and is confirmed by the SPC's own statement '50mg (=5ml)', giving 4 ml = 40 mg and 5 ml = 50 mg, with average durations of action of 80 and 100 minutes in that order; the SPC adds 'The duration of action is dose-dependent'. The only block-height label captured in the flattened table is T10; if the original table carried further rows for other extensions of sensory blockade, those row labels were lost in extraction and are NOT reproduced here. No figure outside 4/5 ml, 40/50 mg and 80/100 minutes is asserted. DOSE INDIVIDUALISATION, §4.2: 'When determining the dose, the patient's physical condition and the concomitant administration of other medicinal products should be taken into consideration... There are wide individual variations with regard to extent and duration of action. The experience of the anaesthetist and knowledge of the patient's general condition are essential for establishing the dose.' SPECIAL POPULATIONS, §4.2: 'It is advisable to reduce the dose in patients in a compromised general condition. In addition, in patients with established concomitant disorders (e.g. vascular occlusion, arteriosclerosis, diabetic polyneuropathy) a reduced dose is indicated.' §4.4 adds that in elderly patients there is an increased risk of high or total spinal block, 'consequently it is advisable to reduce the anaesthetic dose' — no numeric reduction is stated, so none is given here. PAEDIATRIC, §4.2 verbatim: 'The safety and efficacy of Ampres in children and adolescents have not been established. No data are available' — that is why paedDose is null; verify any paediatric use against a children's formulary. PREPARATION, §4.2: 'The medicinal product has to be visually inspected prior to use. Only clear solutions practically free from particles should be used. The intact container must not be re-autoclaved.' RESUSCITATION READINESS, §4.2: 'The equipment, medicinal products and personnel capable of dealing with an emergency, e.g. maintaining the patency of the airways and administering oxygen, must be immediately available.' SODIUM CONTENT, §4.4: 'This medicinal product contains less than 1 mmol sodium (23 mg) per dose (maximum dose equal to 5 ml of Ampres), i.e. essentially "sodium-free".'

Dose adjustments

Renal

No numeric adjustment is stated. §4.4 lists 'Patients with advanced liver or kidney disease' among those requiring special attention and careful observation with ECG monitoring, but gives no dose band or percentage reduction, so none is asserted here.

Hepatic

No numeric adjustment is stated. §4.4: 'Since ester-type local anaesthetics are hydrolysed by plasma cholinesterase produced by the liver, chloroprocaine should be used cautiously in patients with advanced hepatic disease.' Patients with genetic deficiency of plasma cholinesterase also require special attention. No dose band is given, so none is asserted here.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • §4.3, verbatim: 'hypersensitivity to the active substance, medicinal products of the PABA (para-aminobenzoic acid) ester group, other ester-type local anaesthetics or to any of the excipients listed in section 6.1'
  • §4.3: 'general and specific contra-indications to spinal anaesthesia regardless of the local anaesthetic used, should be taken into account (e.g. decompensated cardiac insufficiency, hypovolemic shock)'
  • §4.3: intravenous regional anaesthesia — 'the anaesthetic agent is introduced into the limb and allowed to set in while tourniquets retain the agent within the desired area'
  • §4.3: 'serious problems with cardiac conduction'
  • §4.3: 'severe anaemia'
  • §4.3: 'patients taking anticoagulants or with congenital or acquired bleeding disorder'
  • Not an absolute contraindication but a §4.4 restriction: 'In patients with acute porphyria, Ampres should only be administered when there is a compelling indication for its use, as Ampres may potentially precipitate porphyria.'

Side effects

  • Allergic reactions from sensitivity to the local anaesthetic — §4.8 lists urticaria, pruritus, erythema, angioneurotic oedema with possible airway obstruction (including laryngeal oedema), tachycardia, sneezing, nausea, vomiting, dizziness, syncope, excessive sweating, elevated temperature, and possibly anaphylactoid-type symptomatology including severe hypotension
  • Nervous system — anxiety, restlessness, paraesthesia, dizziness
  • Signs and symptoms of CNS toxicity — backache, headache, tremors possibly proceeding to convulsions, convulsions, circumoral paraesthesia, numbness of the tongue, hearing problems, visual problems, blurred vision, shaking, tinnitus, speech problems, loss of consciousness
  • Neuropathy; drowsiness merging into unconsciousness and respiratory arrest; spinal block of varying magnitude including total spinal block; hypotension secondary to spinal block; loss of bladder and bowel control; loss of perineal sensation and sexual function; arachnoiditis; persistent motor, sensory and/or autonomic (sphincter control) deficit of some lower spinal segments with slow recovery (several months); cauda equina syndrome and permanent neurological injury
  • Cardiac — arrhythmia, depression of the myocardium, cardiac arrest ('the risk is increased by high doses or unintended intravascular injection')
  • Vascular — hypotension (common); bradycardia, hypertension, and hypotension 'raised by high doses'
  • Respiratory depression
  • Gastrointestinal — nausea (common), vomiting
  • Eye disorders — diplopia
  • Anaesthetic complication (injury, poisoning and procedural complications)
  • §4.8 was truncated at the source-fetch limit part-way through the reporting statement, so this list may be incomplete — verify against the full SPC

Monitoring

  • §4.2: equipment, medicinal products and personnel capable of dealing with an emergency must be immediately available; the doctor in charge 'should be fully trained in emergency medicine and resuscitation'
  • §4.2: aspirate a minimum quantity of CSF to confirm correct position before injecting, inject the entire dose slowly, and check vital functions extremely carefully while maintaining continuous verbal contact
  • §4.4: 'Ensuring the presence of reliable venous access is mandatory.'
  • §4.4: careful observation and ECG monitoring in patients with total or partial heart block, high-grade cardiac decompensation, advanced liver or kidney disease, elderly or poor general condition, or on class III antiarrhythmic agents (e.g. amiodarone)
  • §4.4: watch for high or total spinal block — 'Cardiovascular depression is induced by an extended block of the sympathetic nervous system, which may induce severe hypotension and bradycardia to the point of cardiac arrest. Respiratory depression is induced by the block of the respiratory musculature and the diaphragm.'
  • §4.4: 'In case of unintentional intravascular injection severe systemic toxicity may occur immediately.'
  • §4.2: inspect the solution before use — use only clear solutions practically free from particles; the intact container must not be re-autoclaved

Clinical monograph

How it works

It reversibly blocks voltage-gated sodium channels in nerve membranes, inhibiting nerve impulse conduction to produce a rapid-onset, short-duration local anaesthetic effect.

Prescribing in practice

  • Inadvertent intravascular injection can cause systemic CNS and cardiovascular toxicity, so aspirate before injection, use incremental dosing and keep resuscitation facilities available.
  • As an ester anaesthetic it is rapidly hydrolysed by plasma esterases, giving a short duration of action suited to brief procedures.
  • Caution is needed in patients with hypersensitivity to ester-type local anaesthetics or with reduced plasma cholinesterase activity.

Monitoring

Monitor cardiovascular and neurological status and watch for early features of local anaesthetic systemic toxicity during and after injection.

Counselling the patient

  • Explain that numbness is expected and will resolve relatively quickly after a short procedure.
  • Advise reporting dizziness, tinnitus or numbness around the mouth straight away.

Evidence & guidelines

Its use is described in product information and reflects established practice for short-duration regional anaesthesia.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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