An inhaled general anaesthetic called isoflurane (Forane) is used to induce and maintain general anaesthesia.
Isoflurane (Forane) Uses:
-
Anesthesia:
- Inhaled Isoflurane is used in the maintenance of general anesthesia.
- Data regarding its use in obstetrical anesthesia is limited.
Isoflurane dose in Adults:
Note:
- Patients may develop a cough, breath-holding episodes, or laryngospasm during induction;
- An ultra short-acting barbiturate may be used to avoid these symptoms.
- MAC is increased in children and decreased in the elderly.
- Premedication should be selected as needed, taking into account that the drug weakly stimulates secretions and may cause tachycardia.
- The use of anticholinergic drugs with isoflurane is a matter of choice.
Isoflurane (Forane) Dose in the Anesthesia: Inhalation:
-
Induction:
- 1.5% to 3% of isoflurane in oxygen, or an oxygen-nitrous oxide combination.
-
Maintenance:
- Along with 1% to 2.5% nitrous oxide
- Add 0.5% to 1% with oxygen only
Use in Children:
Refer to "Dose in Adults".
Isoflurane (Forane) Pregnancy Risk Category: C
- The placental barrier is permeable to the medication.
- Repeated, extended use of general anaesthesia and drugs that inhibit N-methyl D-aspartate receptors or enhance the action of gamma-aminobutyric acids have been demonstrated to have an impact on brain development. This is based on research on animal reproduction.
- When the surgery will last more than three hours, it is important to weigh the risks and benefits.
- It can cause fetal depression or uterine relaxation when used during obstetrical sedation.
- ACOG recommends that pregnant women may have any life-saving surgery in any trimester. However, elective procedures should be delayed until after delivery.
Use of isoflurane while breastfeeding
- It is unknown if the drug will be excreted into breastmilk.
- Although it is not recommended for lactating mothers to use, it can be used in breastfeeding women.
- When possible, it is recommended that breastmilk be expressed prior to surgery. Breastfeeding can be resumed once the mother is awake.
- At-risk infants, who may have hypotension or apnea, may be able to save milk before and after surgery.
Dose in Kidney Disease:
In the manufacturer’s labeling, an adjustment in the dose has not been provided in patients with kidney disease.
Dose in Liver disease:
In the manufacturer’s labeling, an adjustment in the dose has not been provided in patients with liver disease.
Isoflurane (Forane) Side effects.
-
Cardiovascular:
- Tachycardia (Transient)
- Cardiac Insufficiency
- Hypotension
- Cardiac Arrhythmia
-
Central Nervous System:
- Shivering
- Malignant Hyperthermia
- Cognitive Dysfunction (May Persist For ≤3 Days After Administration)
- Mood Changes (May Persist For ≤6 Days After Administration)
-
Endocrine & Metabolic:
- Hyperkalemia (Perioperative)
- Decreased Serum Cholesterol
- Hyperglycemia
- Decreased Blood Urea Nitrogen
-
Gastrointestinal:
- Nausea
- Intestinal Obstruction
- Vomiting
-
Hematologic & Oncologic:
- Leukocytosis (Transient)
-
Hepatic:
- Decreased Alkaline Phosphatase
-
Neuromuscular & Skeletal:
- Laryngospasm (Related To Induction)
-
Renal:
- Increased Serum Creatinine
-
Respiratory:
- Respiratory Depression
- Cough (Related To Induction)
Contraindications to Isoflurane (Forane):
- Allergy to any of the components, other halogenated substances, or the drug.
Canadian labeling: Additional contraindications not in US labeling
- Patients with a history liver dysfunction or a halogenated anesthetic inhalational medication.
- Patients who have suffered from liver dysfunction, jaundice, unexplained fever, leucocytosis or eosinophilia after the administration of a Halogenated Anesthetic Agent.
- Patients who have a contraindication to general Anesthesia.
Warnings and precautions
-
Cardiovascular effects
- Peripheral vasodilation results in a dose-dependent drop in blood pressure.
- Myocardial infarction, which it can cause, could be problematic for people with coronary artery disease.
- Hypotensive, hypovolemic, and hemodynamically unstable patients should not use this drug.
- QT prolongation is a possibility for patients at high risk. Patients should be cautious about taking the drug.
- Although the drug doesn't cause cardiac conduction defects, nor does it sensitize myocardium for catecholamine-induced cardiac arrhythmias, as is seen with halothane. However, it can cause reflex tachycardia and coronary vasodilation.
-
Reduced blood flow
- It is believed that the drug will reduce hepatic, renal and splenic blood flows.
-
Hepatic effects
- Hepatic dysfunction and sometimes fatal hepatitis have been linked to the drug.
- Patients who were previously sensitive to halogenated drugs are at greater risk for developing hepatitis (sensitivity liver disease).
-
Hyperkalemia
- Inhaled anesthetics can cause perioperative hyperkalemia, which may lead to cardiac arrhythmias. Most patients received succinylcholine concurrently, according to case reports.
- Pediatric patients with an underlying neuromuscular condition, such as Duchenne muscular dystrophy, are more likely to experience hyperkalemia.
- Patients may develop hyperkalemia and myoglobinuria.
- High potassium levels should be checked for arrhythmias and hyperkalemia. Patients should be treated immediately.
-
Increased intracranial pressure
- Because the drug causes cerebral vascular dilation, intracranial pressure may rise because of this.
-
Malignant hyperthermia
- Malignant hyperthermia is possible with this drug. Patients at high risk for malignant hyperthermia should not use it.
-
Anesthesia for obstetrical purposes:
- Isoflurane is associated with higher blood loss during abortions than halothane.
-
Respiratory depression
- Dose-dependent respiratory depression is caused by the drug. It also blunts the ventilatory response to hypoxemia and hypercapnia.
-
Heart Failure:
- The American Heart Association has identified isoflurane as a substance that can aggravate myocardial dysfunction in their scientific statement.
Isoflurane: Drug Interaction
|
Risk Factor C (Monitor therapy) |
|
|
Alcohol (Ethyl) |
Alcohol's CNS depressing effect may be amplified by CNS depressants (Ethyl). |
|
Alfuzosin: |
The hypotensive effects of blood pressure-lowering medications may be strengthened. |
|
Alizapride |
CNS depressants may have an enhanced CNS depressant impact. |
|
Antipsychotic Agents (Second Generation [Atypical]) |
Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). |
|
Barbiturates |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
Benperidol |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
Blood Pressure Lowering Agents |
May enhance the hypotensive effect of HypotensionAssociated Agents. |
|
Brexanolone |
CNS Depressants may enhance the CNS depressant effect of Brexanolone. |
|
Brimonidine (Topical) |
May enhance the CNS depressant effect of CNS Depressants. |
|
Brimonidine (Topical) |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
Bromopride |
May enhance the CNS depressant effect of CNS Depressants. |
|
Cannabidiol |
May enhance the CNS depressant effect of CNS Depressants. |
|
Cannabis |
May enhance the CNS depressant effect of CNS Depressants. |
|
Chlorphenesin Carbamate |
May enhance the adverse/toxic effect of CNS Depressants. |
|
CNS Depressants |
Other CNS depressants' harmful or toxic effects might be exacerbated. |
|
Diazoxide |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
Dimethindene (Topical) |
May enhance the CNS depressant effect of CNS Depressants. |
|
Doxylamine |
May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. |
|
Dronabinol |
May enhance the CNS depressant effect of CNS Depressants. |
|
DULoxetine |
Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. |
|
EPINEPHrine (Nasal) |
The arrhythmogenic effects of inhaled anaesthetics may be increased (Nasal). |
|
EPINEPHrine (Oral Inhalation) |
The arrhythmogenic effects of inhaled anaesthetics may be increased (Oral Inhalation). |
|
Esketamine |
CNS depressants may have an enhanced CNS depressant impact. |
|
Fenoterol |
Inhalational Anesthetics may enhance the arrhythmogenic effect of Fenoterol. |
|
Formoterol |
The arrhythmogenic impact of formoterol may be enhanced by inhalational anaesthetics. |
|
Haloperidol |
QT-prolonging Agents (Indeterminate Risk - Caution) may enhance the QTcprolonging effect of Haloperidol. |
|
Herbs (Hypotensive Properties) |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
HydrOXYzine |
May enhance the CNS depressant effect of CNS Depressants. |
|
Hypotension-Associated Agents |
Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. |
|
Isoniazid |
may lower the serum level of CYP2E1 substrates (High risk with Inhibitors). In particular, it may lower serum concentrations of CYP2E1 substrate below baseline following isoniazid cessation. The serum concentration of CYP2E1 Substrates may rise when isoniazid is used (High risk with Inhibitors). |
|
Kava Kava |
CNS depressants' harmful or toxic effects could be increased. |
|
Levodopa-Containing Products |
Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa-Containing Products. |
|
Lofexidine |
CNS depressants may have an enhanced CNS depressant impact. Management: Separate drug interaction monographs go into further detail about the medications indicated as exceptions to this book. |
|
Lormetazepam |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
Magnesium Sulfate |
May enhance the CNS depressant effect of CNS Depressants. |
|
MetyroSINE |
The sedative effects of metyroSINE may be strengthened by CNS depressants. |
|
Minocycline (Systemic) |
CNS depressants may have an enhanced CNS depressant impact. |
|
Molsidomine |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
Nabilone |
May enhance the CNS depressant effect of CNS Depressants. |
|
Naftopidil |
The hypotensive effects of blood pressure-lowering medications may be strengthened. |
|
Neuromuscular-Blocking Agents (Nondepolarizing) |
The neuromuscular-blocking impact of neuromuscular-blocking agents may be enhanced by inhaled anaesthetics (Nondepolarizing). |
|
Nicergoline |
The hypotensive effects of blood pressure-lowering medications may be strengthened. |
|
Nicorandil |
The hypotensive effects of blood pressure-lowering medications may be strengthened. |
|
Nitroprusside |
Nitroprusside's hypotensive impact may be strengthened by blood pressure-lowering medications. |
|
Pentoxifylline |
The hypotensive effects of blood pressure-lowering medications may be strengthened. |
|
Pholcodine |
Pholcodine's hypotensive impact may be strengthened by blood pressure lowering medications. |
|
Phosphodiesterase 5 Inhibitors |
The hypotensive effects of blood pressure-lowering medications may be strengthened. |
|
Piribedil |
Piribedil's CNS depressing effects may be enhanced by other CNS depressants. |
|
Pramipexole |
The sedative effects of pramipexole might be enhanced by CNS depressants. |
|
Prostacyclin Analogues |
The hypotensive effects of blood pressure-lowering medications may be strengthened. |
|
QT-prolonging Agents (Highest Risk) |
QT-prolonging Agents (Indeterminate Risk - Caution) may enhance the QTc-prolonging effect of QT-prolonging Agents (Highest Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. |
|
Quinagolide |
May enhance the hypotensive effect of Blood Pressure Lowering Agents. |
|
Ritodrine |
May enhance the adverse/toxic effect of Inhalational Anesthetics. |
|
ROPINIRole |
CNS Depressants may enhance the sedative effect of ROPINIRole. |
|
Rotigotine |
CNS Depressants may enhance the sedative effect of Rotigotine. |
|
Rufinamide |
May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. |
|
Selective Serotonin Reuptake Inhibitors |
CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. |
|
Tetrahydrocannabinol |
May enhance the CNS depressant effect of CNS Depressants. |
|
Tetrahydrocannabinol and Cannabidiol |
May enhance the CNS depressant effect of CNS Depressants. |
|
Trimeprazine |
May enhance the CNS depressant effect of CNS Depressants. |
|
Risk Factor D (Consider therapy modification) |
|
|
Amifostine |
Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered. |
|
Bambuterol |
May enhance the arrhythmogenic effect of Inhalational Anesthetics. Management: Some labels recommend specifically avoiding halothane; others recommend separating administration by at least 6 hours; other bambuterol labels do not mention this possible interaction. |
|
Blonanserin |
CNS Depressants may enhance the CNS depressant effect of Blonanserin. |
|
Buprenorphine |
CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. |
|
Chlormethiazole |
May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. |
|
CYP2E1 Inhibitors (Strong) |
May decrease the metabolism of CYP2E1 Substrates (High risk with Inhibitors). |
|
Droperidol |
CNS depressants may have an enhanced CNS depressant impact. Consider lowering the dosage of droperidol or other CNS drugs (such as opioids or barbiturates) when they are used concurrently. In separate drug interaction monographs, exceptions to this monograph are covered in more detail. |
|
EPINEPHrine (Systemic) |
The arrhythmogenic effects of inhaled anaesthetics may be increased (Systemic). Treatment: When treating patients who are now receiving or have just had inhalational anaesthetics, provide epinephrine with extra caution. Use epinephrine at lower dosages than usual and keep an eye out for the emergence of cardiac arrhythmias. |
|
Flunitrazepam |
Flunitrazepam's CNS depressing effects may be enhanced by other CNS depressants. |
|
HYDROcodone |
The CNS depressive action of HYDROcodone may be enhanced by CNS depressants. Management: Whenever feasible, refrain from using hydrocodone and benzodiazepines or other CNS depressants concurrently. Only in the event that other treatment choices are insufficient should these medications be combined. Limit the duration and dosage of each medicine when used together |
|
Lemborexant |
CNS depressants may have an enhanced CNS depressant impact. Management: Due to the possibility of additive CNS depressant effects when lemborexant and concurrent CNS depressants are administered concurrently, dosage modifications may be required. Effects of CNS depressants must be closely monitored. |
|
Methotrimeprazine |
CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after a clinically effective methotrimeprazine dose is established. |
|
Obinutuzumab |
The hypotensive effects of blood pressure-lowering medications may be strengthened. Management: Take into account temporarily stopping blood pressure-lowering drugs 12 hours before the start of the obinutuzumab infusion and keeping them off until 1 hour after the infusion is finished. |
|
Opioid Agonists |
Opioid agonists' CNS depressing effects may be amplified by CNS depressants. Management: When at all possible, refrain from using benzodiazepines or other CNS depressants concurrently with opioid agonists. Only in the event that other treatment choices are insufficient should these medications be combined. Limit the duration and dosage of each medicine when used together. |
|
OxyCODONE |
CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. |
|
Perampanel |
May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination until they have experience using the combination. |
|
Sodium Oxybate |
CNS depressants may have an enhanced CNS depressant impact. Management: Take into account substitutes for combined use. Reduce the doses of one or more medications when simultaneous use is necessary. It is not advised to use sodium oxybate with alcoholic beverages or hypnotic sedatives. |
|
Suvorexant |
Suvorexant's CNS depressing effects may be amplified by other CNS depressants. Treatment: Suvorexant and/or any other CNS depressant dosage reduction may be required. Suvorexant shouldn't be taken with alcohol, and it shouldn't be taken for sleeplessness with any other medication either. |
|
Tapentadol |
CNS depressants may have an enhanced CNS depressant impact. Treatment: When feasible, refrain from using tapentadol and benzodiazepines or other CNS depressants simultaneously. Only in the event that other treatment choices are insufficient should these medications be combined. Limit the duration and dosage of each medicine when used together. |
|
Zolpidem |
CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. |
|
Risk Factor X (Avoid combination) |
|
|
Azelastine (Nasal) |
CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). |
|
Bromperidol |
Blood Pressure Lowering Agents may enhance the hypotensive effect of Bromperidol. Bromperidol may diminish the hypotensive effect of Blood Pressure Lowering Agents. |
|
Bromperidol |
May enhance the CNS depressant effect of CNS Depressants. |
|
Dexmethylphenidate |
May enhance the hypertensive effect of Inhalational Anesthetics. |
|
DOPamine |
DOPamine's ability to induce arrhythmias may be enhanced by inhalational anaesthetics. Management: Patients receiving halogenated hydrocarbon anaesthetics should not be given dopamine. Watch for arrhythmia if concurrent treatment cannot be avoided. Based on studies from animals, propranolol may be able to reverse ventricular arrhythmia brought on by dopamine. |
|
Ephedra |
Can make inhalational anaesthetics more arrhythmogenic. |
|
EPHEDrine (Nasal) |
Can make inhalational anaesthetics more arrhythmogenic. |
|
EPHEDrine (Systemic) |
Can make inhalational anaesthetics more arrhythmogenic. |
|
Isoproterenol |
Isoproterenol's ability to cause heart arrhythmias may be increased by inhalational anaesthetics. |
|
Metaraminol |
Isoproterenol's ability to cause heart arrhythmias may be increased by inhalational anaesthetics. |
|
Methylphenidate |
Inhalational anaesthetics' tendency to cause hypertension may be enhanced. |
|
Norepinephrine |
Norepinephrine's ability to induce arrhythmias may be enhanced by inhalational anaesthetics. |
|
Orphenadrine |
The CNS depressing action of orphenadrine may be enhanced by CNS depressants. |
|
Oxomemazine |
CNS depressants may have an enhanced CNS depressant impact. |
|
Paraldehyde |
The CNS depressing effects of paraldehyde may be enhanced by CNS depressants. |
|
Thalidomide |
The CNS depressing effect of thalidomide may be enhanced by CNS depressants. |
Monitoring parameters:
- Isoflurane concentrations before and throughout anesthesia
- Blood pressure
- Oxygen saturation
- Heart rate and rhythm
- End-tidal CO2
- Serum potassium
How to administer Isoflurane (Forane)?
It is administered through an isoflurane-specific calibrated vaporizer or vaporizer with calculated flow required.
Mechanism of action of Isoflurane (Forane):
Isoflurane, an inhaled anesthetic, is used for general anesthesia. It can cause severe respiratory depression. It alters neuronal activity, especially in fast-acting neurotransmitter receivers like nicotinic acid, gamma-aminobutyric acids, and glutamate. It can decrease contractility in the myocardium, lower blood pressure due to its vasodilatory effect (reduce systemic resistance) and reduce the activity of the sympathetic nervous system.
Metabolism:
- Metabolized minimally in the liver (<0.2%), predominantly CYP2E1.
Excretion:
- Exhaled gases
International Brand Names of Isoflurane:
- Forane
- Terrell
- Aerane
- Aerrane
- AErrane
- Anahal
- Floran
- Florane
- Flurane
- Fluren
- Forane
- Forene
- Forthane
- Isocane
- Isofluran
- Isofluran Pharmacia
- Isoflurane
- Isoflurano
- Isofor
- Isoplan
- Isorane
- Isotan
- Sofloran
- Terrell
- Terrell Soln
- Zuflax
Isoflurane Brand Names in Pakistan:
Isoflurane Liquid 2 %w/v in Pakistan |
|
| Isoflurane | Akhai Pharmaceuticals. |
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