Product Name:Sevoflurane for inhalation
Nombre del Producto:Sevoflurano para inhalación
Standard: USP& BP
Posology and method of administration
Premedication should be selected according to the need of the individual patient, and at the discretion of the anaesthetist.
Sevoflurane should be delivered via a vaporiser specifically calibrated for use with sevoflurane so that the concentration delivered can be accurately controlled. MAC (minimum alveolar concentration) values for sevoflurane decrease with age and with the addition of nitrous oxide. The table below indicates average MAC values for different age groups.
Table 1: MAC values for Adults and Paediatric patients according to age
Age of Patient (years) Sevoflurane in Oxygen Sevoflurane in 65% N2O/35% O2
0 – 1 months* 3.3% 2.0%**
1 - < 6 months 3.0%
6 months - < 3 years 2.8%
3 - 12 2.5%
25 2.6% 1.4%
40 2.1% 1.1%
60 1.7% 0.9%
80 1.4% 0.7%
* Neonates are full term gestational age. MAC in premature infants has not been determined.
** In 1 – <3 year old paediatric patients, 60% N2O/40% O2 was used.
Dosage should be individualised and titrated to the desired effect according to the patient's age and clinical status. A short acting barbiturate or other intravenous induction agent may be administered followed by inhalation of sevoflurane. Induction with sevoflurane may be achieved in oxygen or in combination with oxygen-nitrous oxide mixtures. In adults inspired concentrations of up to 5% sevoflurane usually produce surgical anaesthesia in less than 2 minutes. In children, inspired concentrations of up to 7% sevoflurane usually produce surgical anaesthesia in less than 2 minutes. Alternatively, for induction of anaesthesia in unpremedicated patients, inspired concentrations of up to 8% sevoflurane may be used.
Surgical levels of anaesthesia may be sustained with concentrations of 0.5 - 3% sevoflurane with or without the concomitant use of nitrous oxide.
Emergence times are generally short following sevoflurane anaesthesia. Therefore, patients may require early post-operative pain relief.
MAC decreases with increasing age. The average concentration of sevoflurane to achieve MAC in an 80 year old is approximately 50% of that required in a 20 year old.
Refer to Table 1 for MAC values for paediatric patients according to age.
Sevoflurane should not be used in patients with known or suspected sensitivity to sevoflurane or other halogenated anaesthetics (e.g. history of liver function disorder, fever or leucocytosis of unknown cause after anaesthesia with one of these agents).
Sevoflurane is also contraindicated in patients with known or suspected genetic susceptibility to malignant hyperthermia.
Sevoflurane is contraindicated in patients in whom general anaesthesia is contraindicated.
Special warnings and precautions for use
Sevoflurane may cause respiratory depression, which may be augmented by narcotic premedication or other agents causing respiratory depression. Respiration should be supervised and if necessary, assisted.
Sevoflurane should be administered only by persons trained in the administration of general anaesthesia. Facilities for maintenance of a patent airway, artificial ventilation, oxygen enrichment and circulatory resuscitation must be immediately available.
The concentration of sevoflurane being delivered from a vaporiser must be known exactly. As volatile anaesthetics differ in their physical properties, only vaporisers specifically calibrated for sevoflurane must be used. The administration of general anaesthesia must be individualised based on the patient's response. Hypotension and respiratory depression increase as anaesthesia is deepened.
In susceptible individuals, potent inhalation anaesthetic agents may trigger a skeletal muscle hypermetabolic state leading to high oxygen demand and the clinical syndrome known as malignant hyperthermia. The clinical syndrome is signalled by hypercapnia, and may include muscle rigidity, tachycardia, tachypnoea, cyanosis, arrhythmias, and/or unstable blood pressure. Some of these nonspecific signs may also appear during light anaesthesia, acute hypoxia, hypercapnia and hypovolaemia.
In clinical trials, one case of malignant hyperthermia was reported. In addition, there have been postmarketing reports of malignant hyperthermia. Some of these reports have been fatal.
Treatment includes discontinuation of triggering agents (e.g. sevoflurane), administration of intravenous dantrolene sodium (consult prescribing information for intravenous dantrolene sodium for additional information on patient management), and application of supportive therapy. Such therapy includes vigorous efforts to restore body temperature to normal, respiratory and circulatory support as indicated, and management of electrolyte-fluid-acid-base abnormalities. Renal failure may appear later, and urine flow should be monitored and sustained if possible.
Use of inhaled anaesthetic agents has been associated with rare increases in serum potassium levels that have resulted in cardiac arrhythmias and death in paediatric patients during the postoperative period. Patients with latent as well as overt neuromuscular disease, particularly Duchenne muscular dystrophy, appear to be most vulnerable. Concomitant use of succinylcholine has been associated with most, but not all, of these cases. These patients also experienced significant elevations in serum creatine kinase levels and, in some cases, changes in urine consistent with myoglobinuria. Despite the similarity in presentation to malignant hyperthermia, none of these patients exhibited signs or symptoms of muscle rigidity or hypermetabolic state. Early and aggressive intervention to treat the hyperkalaemia and resistant arrhythmias is recommended, as is subsequent evaluation for latent neuromuscular disease.
Isolated reports of QT prolongation, very rarely associated with torsade de pointes (in exceptional cases, fatal), have been received. Caution should be exercised when administering sevoflurane to susceptible patients.
Isolated cases of ventricular arrhythmia were reported in paediatric patients with Pompe's disease.
Caution should be exercised in administering general anaesthesia, including sevoflurane, to patients with mitochondrial disorders.
Very rare cases of mild, moderate and severe post-operative hepatic dysfunction or hepatitis with or without jaundice have been reported from postmarketing experiences.
Clinical judgment should be exercised when sevoflurane is used in patients with underlying hepatic conditions or under treatment with drugs known to cause hepatic dysfunction
Patients with repeated exposures to halogenated hydrocarbons, including sevoflurane, within a relatively short interval may have an increased risk of hepatic injury.
During the maintenance of anaesthesia, increasing the concentration of sevoflurane produces dose-dependent decreases in blood pressure. Excessive decrease in blood pressure may be related to depth of anaesthesia and in such instances may be corrected by decreasing the inspired concentration of sevoflurane. Particular care must be taken when selecting the dosage for patients who are hypovolaemic, hypotensive, or otherwise hemodynamically compromised, e.g., due to concomitant medications.
As with all anaesthetics, maintenance of haemodynamic stability is important to avoid myocardial ischaemia in patients with coronary artery disease.
Caution should be observed when using sevoflurane during obstetric anaesthesia because the relaxant effect on the uterus could increase the risk of uterine bleeding (see section 4.6).
The recovery from general anaesthesia should be assessed carefully before patients are discharged from the recovery room. Rapid emergence from anaesthesia is generally seen with sevoflurane so early relief of postoperative pain may be required. Although recovery of consciousness following sevoflurane administration generally occurs within minutes, the impact on intellectual function for two or three days following anaesthesia has not been studied. As with other anaesthetics, small changes in moods may persist for several days following administration. Rapid emergence in children may be associated with agitation and lack of co-operation (in about 25% of cases).
Replacement of Desiccated CO2 Absorbents:
Rare cases of extreme heat, smoke, and/or spontaneous fire in the anaesthesia machine have been reported during sevoflurane use in conjunction with the use of desiccated CO2 absorbent, specifically those containing potassium hydroxide (e.g Baralyme). An unusually delayed rise or unexpected decline of inspired sevoflurane concentration compared to the vaporiser setting may be associated with excessive heating of the CO2 absorbent canister.
An exothermic reaction, enhanced sevoflurane degradation, and production of degradation products can occur when the CO2 absorbent becomes desiccated, such as after an extended period of dry gas flow through the CO2 absorbent canisters. Sevoflurane degradants (methanol, formaldehyde, carbon monoxide, and Compounds A, B, C, and D) were observed in the respiratory circuit of an experimental anaesthesia machine using desiccated CO2 absorbents and maximum sevoflurane concentrations (8%) for extended periods of time (≥ 2 hours). Concentrations of formaldehyde observed at the anaesthesia respiratory circuit (using sodium hydroxide containing absorbents) were consistent with levels known to cause mild respiratory irritation. The clinical relevance of the degradants observed under this extreme experimental model is unknown.
If a health care professional suspects that the CO2 absorbent has become desiccated, it must be replaced before subsequent use of volatile anaesthetics (such as sevoflurane). It must be taken into account that the colour indicator does not always change after desiccation has taken place. Therefore, the lack of significant colour change should not be taken as an assurance of adequate hydration. CO2 absorbents should be replaced routinely regardless of the state of the colour indicator.
Because of the small number of patients with renal insufficiency (baseline serum creatinine greater than 1.5mg/dL) studied, the safety of sevoflurane administration in this group has not been fully established. Therefore, sevoflurane should be used with caution in patients with renal insufficiency.
In some studies in rats, nephrotoxicity was seen in animals exposed to levels of Compound A (pentafluoroisopropenyl fluoromethyl ether (PIFE)) in excess of those usually seen in routine clinical practice. The mechanism of this renal toxicity in rats is unknown and its relevance to man has not been established.
Neurosurgery & Neuromuscular Impairment:
In patients at risk from elevation of intra-cranial pressure, sevoflurane should be administered cautiously in conjunction with techniques to lower intra-cranial pressure (e.g. hyperventilation).
Rare cases of seizures have been reported in association with sevoflurane use.
Use of sevoflurane has been associated with seizures occurring in children and young adults as well as older adults with and without predisposing risk factors. Clinical judgment is necessary before sevoflurane is used in patients at risk of seizures. In children the depth of anaesthesia should be limited. EEG may permit the optimization of sevoflurane dose and help avoid the development of seizure activity in patients with a predisposition for seizures.
The use of sevoflurane has been associated with seizures. Many have occurred in children and young adults starting from 2 months of age, most of whom had no predisposing risk factors. Clinical judgment should be exercised when using sevoflurane in patients who may be at risk for seizures .
Dystonic movements in children have been observed .
Interaction with other medicinal products and other forms of interaction
Beta-sympathomimetic agents like isoprenaline and alpha- and beta- sympathomimetic agents like adrenaline and noradrenaline should be used with caution during Sevoflurane narcosis, due to a potential risk of ventricular arrhythmia.
Non-selective MAO-inhibitors: Risk of crisis during the operation. It is generally recommended that treatment should be stopped 2 weeks prior to surgery.
Sevoflurane may lead to marked hypotension in patients treated with calcium antagonists, in particular dihydropyridine derivates.
Caution should be exercised when calcium antagonists are used concomitantly with inhalation anesthetics due to the risk of additive negative inotropic effect.
Concomitant use of succinylcholine with inhaled anesthetic agents has been associated with rare increases in serum potassium levels that have resulted in cardiac arrhythmias and death in pediatric patients during the post-operative period.
Sevoflurane has been shown to be safe and effective when administered concurrently with a wide variety of agents commonly encountered in surgical situations such as central nervous system agents, autonomic drugs, skeletal muscle relaxants, anti-infective agents including aminoglycosides, hormones and synthetic substitutes, blood derivatives and cardiovascular drugs, including epinephrine.
Sevoflurane is similar to isoflurane in the sensitisation of the myocardium to the arrhythmogenic effect of exogenously administered adrenaline.
There is a risk of acute hypertensive episode with the concomitant use of sevoflurane and indirect-acting sympathomimetics products (amphetamines, ephedrine).
Sevoflurane may increase the negative inotropic, chronotropic and dromotropic effects of beta blockers (by blocking cardiovascular compensatory mechanisms).
Impairment of atrioventricular conduction was observed when verapamil and sevoflurane were administered at the same time.
Inducers of CYP2E1
Medicinal products and compounds that increase the activity of cytochrome P450 isoenzyme CYP2E1, such as isoniazid and alcohol, may increase the metabolism of sevoflurane and lead to significant increases in plasma fluoride concentrations. Concomitant use of sevoflurane and isoniazid can potentiate the hepatotoxic effects of isoniazid.
St John's Wort
Severe hypotension and delayed emergence from anaesthesia with halogenated inhalational anaesthetics have been reported in patients treated long-term with St John's Wort.
Sevoflurane administration is compatible with barbiturates as commonly used in surgical practice.
Benzodiazepines and Opioids
Benzodiazepines and opioids are expected to decrease the MAC of sevoflurane in the same manner as with other inhalational anaesthetics. Sevoflurane administration is compatible with benzodiazepines and opioids as commonly used in surgical practice.
Opioids such as alfentanil and sufentanil, when combined with sevoflurane, may lead to a synergistic fall in heart rate, blood pressure and respiratory rate.
As with other halogenated volatile anaesthetics, the MAC of sevoflurane is decreased when administered in combination with nitrous oxide. The MAC equivalent is reduced approximately 50% in adult and approximately 25% in paediatric patients .
Neuromuscular Blocking Agents
As with other inhalational anaesthetic agents, sevoflurane affects both the intensity and duration of neuromuscular blockade by non-depolarising muscle relaxants. When used to supplement alfentanil-N2O anaesthesia, sevoflurane potentiates neuromuscular block induced with pancuronium, vecuronium or atracurium. The dosage adjustments for these muscle relaxants when administered with sevoflurane are similar to those required with isoflurane. The effect of sevoflurane on succinylcholine and the duration of depolarising neuromuscular blockade has not been studied.
Dosage reduction of neuromuscular blocking agents during induction of anaesthesia may result in delayed onset of conditions suitable for endotracheal intubation or inadequate muscle relaxation because potentiation of neuromuscular blocking agents is observed a few minutes after the beginning of sevoflurane administration.
Among non-depolarising agents, vecuronium, pancuronium and atracurium interactions have been studied. In the absence of specific guidelines: (1) for endotracheal intubation, do not reduce the dose of non-depolarising muscle relaxants; and, (2) during maintenance of anaesthesia, the dose of non-depolarising muscle relaxants is likely to be reduced compared to that during N2O/opioid anaesthesia. Administration of supplemental doses of muscle relaxants should be guided by the response to nerve stimulation.
As with other agents, lesser concentrations of sevoflurane may be required following use of an intravenous anaesthetic e.g. propofol.
Significant increases in plasma fluoride concentrations have been observed following the increased activity of CYP 2E1.
Fertility, pregnancy and lactation
Sevoflurane has a relaxant effect on the uterus, which can lead to increased uterine bleeding, as was reported in a study of its use during termination of pregnancy. Use during labour and delivery is limited to one small study in caesarean section.
Reproduction studies in rats and rabbits at doses up to 1 MAC have revealed no evidence of harm to the fetus due to sevoflurane. There are no adequate and well-controlled studies in pregnant women; therefore, sevoflurane should be used during pregnancy only if clearly needed.
Labour and Delivery
In a clinical trial, the safety of sevoflurane was demonstrated for mothers and infants when used for anaesthesia during Caesarean section. The safety of sevoflurane in labour and vaginal delivery has not been demonstrated.
It is not known whether sevoflurane or its metabolites are excreted in human milk. Due to the absence of documented experience, women should be advised to skip breast-feeding for 48 hours after administration of sevoflurane and discard milk produced during this period.
Reproduction studies in rats and rabbits at doses up to 1 MAC have revealed no evidence of impaired fertility due to sevoflurane.
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