It is unlikely that Chloroprocain HCl Sintetica 1%, at the recommended posology by intrathecal administration, will induce plasma levels capable of inducing systemic toxicity.
Acute systemic toxicity
Systemic undesirable effects are of methodological (due to use), pharmacodynamic or pharmacokinetic origin and concern the central nervous system and the cardiocirculatory system.
Iatrogenic undesirable effects occur:
− after injecting an excessive quantity of solution
− from accidental injection into a vessel
− from incorrect patient position
− from high spinal anaesthesia (marked drop in arterial pressure)
In the case of accidental intravenous administration, the toxic effect occurs within 1 minute. In mice, the intravenous LD50 of chloroprocaine HCl is 97 mg/kg
Signs of overdose can be classified into two different sets of symptoms which differ in terms of quality and intensity:
a) Symptoms affecting the central nervous system
Generally, the first symptoms are paresthesia in the mouth area, feeling of numbness of the tongue, feeling dazed, problems with hearing and tinnitus. Visual problems and muscle contractions are more severe and precede a generalized convulsion. These signs must not be erroneously mistaken for neurotic behaviour. Subsequently loss of consciousness and tonic-clonic seizure may occur, generally lasting between a few seconds and a few minutes. The convulsions are immediately followed by hypoxia and increased levels of carbon dioxide in the blood (hypercapnia), attributable to increased muscular activity associated with respiratory problems. In serious cases respiratory arrest may occur. Acidosis and/or hypoxia potentiate the toxic effects of local anaesthetics.
The reduction or improvement of symptoms affecting the central nervous system can be attributed to the redistribution of local anaesthetic outside the CNS, with its consequent metabolism and excretion. Regression may be rapid, unless enormous quantities have been used.
b) Cardiovascular symptoms
In serious cases cardiovascular toxicity may occur. Hypotension, bradycardia, arrhythmia and also cardiac arrest may occur in the presence of a high systemic concentration of local anaesthetics.
The first signs of toxic symptoms affecting the central nervous system generally precede toxic cardiovascular effects. This statement does not apply if the patient is under general anaesthesia or heavily sedated with medicinal products such as benzodiazepine or barbiturates.
Treatment of acute systemic toxicity
The following measures must be taken immediately:
− Stop administration of Chloroprocain HCl Sintetica 1%.
− Ensure an adequate supply of oxygen: keep the airways clear, administer O2, artificial ventilation (intubation) if required.
− In case of cardiovascular depression circulation must be stabilized.
If convulsions occur and do not resolve spontaneously after 15-20 seconds, the administration of an intravenous anticonvulsant is recommended.
Analeptics with a central action are contraindicated in the case of intoxication caused by local anaesthetics!
In the event of serious complications, when treating the patient it is advisable to obtain the assistance of a doctor specializing in emergency medicine and resuscitation (e.g. anaesthetist).
In patients with genetic deficiency of plasma cholinesterase an intravenous lipid solution could be administered.
- 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….)
- intravenous regional anaesthesia (the anesthetic agent is introduced into the limb and allowed to set in while tourniquets retain the agent within the desired area)
- serious problems with cardiac conduction,
- severe anaemia,
It is also necessary to take into consideration general and specific contraindications for the technique of spinal anaesthesia = intrathecal anaesthesia.
In the absence of compatibility studies, this medicinal product must not be mixed with other medicinal products.
The possible undesirable effects due to the use of Chloroprocain HCl Sintetica 1% are generally similar to the undesirable effects of other local anaesthetics for spinal anaesthesia from the ester group. The undesirable effects induced by the medicinal product are difficult to distinguish from the physiological effects of the nerve block (e.g. reduction in arterial pressure, bradycardia, temporary urine retention), from direct effects (e.g. spinal hematoma) or the indirect effects (e.g. meningitis) of the injection or from the effects due to the loss of cerebrospinal liquid (e.g. post-spinal headache).
The frequency of undesirable effects listed below is defined using the following convention:
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), Very rare (<1/10,000), Not known (cannot be estimated from the available data).
Immune system disorders
Rare: allergic reactions as a result of sensitivity to the local anaesthetic, characterized by signs such as urticaria, pruritus, erythema, angioneurotic edema with possible airway obstruction (including laryngeal edema), tachycardia, sneezing, nausea, vomiting, dizziness, syncope, excessive sweating, elevated temperature, and possibly, anaphylactoid type symptomatology (including severe hypotension).
Nervous system disorders
Common: anxiety, restlessness, paresthesia, dizziness.
Uncommon: signs and symptoms of CNS toxicity (backache, headache, tremors possibly proceeding to convulsions, convulsions, circumoral paresthesia, feeling of numbness affecting the tongue, hearing problems, visual problems, blurred vision, shaking, tinnitus, speech problems, loss of consciousness).
Rare: 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, and 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.
Eye disorders
Rare: diplopia
Cardiac disorders
Rare: arrhythmia, depression of the myocardium, cardiac arrest (the risk is increased by high doses or unintended intravascular injection).
Vascular disorders
Very common: hypotension.
Uncommon: bradycardia, hypertension, hypotension raised by high doses.
Respiratory, thoracic and mediastinal disorders
Rare: respiratory depression
Gastrointestinal disorders
Very common: nausea
Common: vomiting.
Effects in non-clinical studies were observed only at exposures considered sufficiently in excess of the maximum human exposure indicating little relevance to clinical use.
No studies in animals to evaluate carcinogenic potential and reproductive and developmental toxicity have been conducted with chloroprocaine.
In vitro genotoxicity studies didn't provide evidence for 2-chloroprocaine to have a relevant mutagenic or clastogenic potential.
Spinal anaesthesia in adults where the planned surgical procedure should not exceed 40 minutes.
Pharmacotherapeutic group: anaesthetics, local; esters of aminobenzoic acid
ATC code: N01BA04
Chloroprocaine, is an ester-type local anaesthetic. Chloroprocaine, blocks the generation and the conduction of nerve impulses, presumably by increasing the threshold for electrical excitation in the nerve, by slowing the propagation of the nerve impulse and by reducing the rate of rise of the action potential.
The onset of action for spinal administration is very rapid (9.6 min ± 7.3 min at 40 mg dose; 7.9 min ± 6.0 min at 50 mg dose) and the duration of anaesthesia may be up to 100 minutes.
Paediatric population
The European Medicines Agency has waived the obligation to submit the results of studies with Chloroprocain HCl Sintetica 1% in the first three subsets of the paediatric population and has deferred the obligation to submit the results in adolescent as per Paediatric Investigation Plan (PIP) decision.
Absorption and Distribution
The plasma concentration should be negligible for intrathecal use.
Biotransformation
Chloroprocaine is rapidly metabolized in plasma by hydrolysis of the ester linkage by pseudocholinesterase. This process could be decelerated in case of pseudocholinesterase deficiency.
The hydrolysis of chloroprocaine results in the production of ßdiethylaminoethanol and 2-chloro-4-aminobenzoic acid.
The in vitro plasma half-life of chloroprocaine in adults is 21 ± 2 seconds for males and 25 ± 1 seconds for females. The in vitro plasma half-life in neonates is 43 ± 2 seconds. In women, plasma half-lives in vivo of 3.1 ±1.6 minutes was measured.
Elimination
The metabolites, ßdiethylaminoethanol and 2-chloro-4-aminobenzoic acid, are excreted by the kidney into the urine.
Pharmacokinetic in spine
Elimination of chloroprocaine from the CSF is entirely by diffusion and vascular absorption, either in neural tissues in the intrathecal space or by crossing the dura along the concentration gradient between CSF and the epidural space. Consequently, chloroprocaine is subject to vascular absorption. The predominant factors determining the rate of absorption are local blood flow and competing binding to local tissues, but not enzymatic hydrolysis in the CSF. In patients with cholinesterase deficiency it is reasonable to expect very low peak plasma levels of chloroprocaine after intrathecal injection. Clearance of chloroprocaine from CSF by diffusion across the dura into the epidural space and subsequent systemic absorption may not be impaired to a clinically significant degree.
Spinal anaesthesia must only be administered by anaesthetists with the necessary knowledge and experience in the intrathecal anesthesia domain. The doctor in charge is responsible for taking the measures needed to avoid an intravascular injection and should be fully trained in emergency medicine and resuscitation to be ready to prevent and treat the side effects and complication of the procedure.
In addition, it is essential for the doctor to know how to recognize and treat undesirable effects, systemic toxicity and other complications. If signs of acute systemic toxicity or total spinal block are observed, the injection of the local anaesthetic must be stopped immediately.
Some patients require special attention in order to reduce the risk of serious undesirable effects, even when locoregional anaesthesia constitutes the optimum choice for the surgical intervention:
− Patients with total or partial heart block, since local anaesthetics can suppress myocardial conduction.
− Patients with high grade cardiac decompensation.
− Patients with advanced liver or kidney damage.
− Elderly patients and patients in poor general condition.
− Patients treated with class III antiarrhythmic agents (e.g. amiodarone). These patients should be subjected to careful observation and ECG monitoring, since cardiac effects may be added.
− In patients with acute porphyria, Chloroprocain HCl Sintetica 1% should only be administered when there is a compelling indication for its use, as Chloroprocain HCl Sintetica 1% may potentially precipitate porphyria. Appropriate precautions should be taken in all patients with porphyria.
− Since ester-type local anaesthetics are hydrolyzed 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
Ensuring the presence of reliable venous access is mandatory.
Hypotension and bradicardia are well known side effects of all local anesthestics.
In high risk patients, the recommendation is to improve their general condition prior to the intervention.
A rare, but serious, undesirable effect of spinal anaesthesia is high or total spinal block, with consequent cardiovascular and respiratory depression. 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.
Especially in elderly patients there is an increased risk of high or total spinal block: consequently it is advisable to reduce the anaesthetic dose.
Particularly in the case of elderly patients, an unexpected drop in arterial pressure may occur as a complication of spinal anaesthesia.
Rarely, neurological damage may occur after spinal anaesthesia, manifesting as paresthesia, loss of sensitivity, motor weakness, paralysis, cauda equina syndrome and permanent neurological injury.
Occasionally these symptoms persist.
There is no suspicion that neurological disorders, such as multiple sclerosis, hemiplegia, paraplegia or neuromuscular disorders may be negatively influenced by spinal anaesthesia. Nevertheless, it should be used with care. Careful evaluation of the risk-benefit ratio is recommended prior to treatment.
This medicinal product contains less then 1 mmol sodium (23 mg) per dose (maximum dose equal to 5 ml of Chloroprocain HCl Sintetica 1%), i.e. essentially “sodium-freeâ€.
Chloroprocain HCl Sintetica 1% has major influence on the ability to drive and use machines
The doctor is responsible for deciding in each individual case if the patient can drive or use machines.
Posology
Posology must be established on an individual basis in accordance with the characteristics of the specific case. When determining the dose, take into consideration the patient's physical condition and the concomitant administration of other medicinal products.
The duration of action is dose-dependent.
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. 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.
With regard to posology the following guidelines are applied:
Posology Adults
| Extension of sensory blockade required T10 | ml | mg | Average duration of action (minutes) |
| 4 5 | 40 50 | 80 100 |
The maximum recommended dose is 50mg (=5ml) of chloroprocaine hydrochloride.
Special population
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.
Pediatric population
Chloroprocain HCl Sintetica 1% must not be used in children and adolescents.
Method of administration
For intrathecal use.
Precautions to be taken before administering the medicinal product.
The equipment, drugs and personnel capable of dealing with an emergency, e.g. maintaining the patency of the airways and administering oxygen, must be immediately available, since in rare cases severe reactions, sometimes with a fatal outcome, have been reported after using local anaesthetics, even in the absence of individual hypersensitivity in the patient's case history.
Inject Chloroprocain HCl Sintetica 1% via intrathecal route into the intervertebral space L2/L3, L3/L4 and L4/L5.
Slowly inject the entire dose and check the patient's vital functions extremely carefully maintaining continuous verbal contact.
In general the following points should be taken into consideration:
1. Choose the lowest possible dose!
2. Administer the injection slowly, after having aspirated a minimum quantity of CSF to confirm the correct position
3. Do not puncture the skin if there are signs of infection or inflammation
4. Spinal anaesthesia = intrathecal anaesthesia should not be performed in patients taking anticoagulants or with congenital or acquired bleeding disorder.
For single use. Any unused solution should be discarded.
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.
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
