Forthane

Forthane Uses, Dosage, Side Effects, Food Interaction and all others data.

Forthane may be used for induction and maintenance of general anesthesia. Adequate data have not been developed to establish its application in obstetrical anesthesia.

Induction of and recovery from Forthane anesthesia are rapid. Forthane has a mild pungency, which limits the rate of induction, although excessive salivation or tracheobronchial secretions do not appear to be stimulated. Pharyngeal and laryngeal reflexes are readily obtunded. The level of anesthesia may be changed rapidly with Forthane. Forthane is a profound respiratory depressant. Respiration must be monitored closely and supported when necessary. As anesthetic dose is increased, tidal volume decreases and respiratory rate is unchanged. This depression is partially reversed by surgical stimulation, even at deeper levels of anesthesia. Forthane evokes a sigh response reminiscent of that seen with diethyl ether and enflurane, although the frequency is less than with enflurane.

Blood pressure decreases with induction of anesthesia but returns toward normal with surgical stimulation. Progressive increases in depth of anesthesia produce corresponding decreases in blood pressure. Nitrous oxide diminishes the inspiratory concentration of Forthane required to reach a desired level of anesthesia and may reduce the arterial hypotension seen with Forthane alone. Heart rhythm is remarkably stable. With controlled ventilation and normal PaCO2, cardiac output is maintained despite increasing depth of anesthesia, primarily through an increase in heart rate, which compensates for a reduction in stroke volume. The hypercapnia, which attends spontaneous ventilation during Forthane anesthesia further increases heart rate and raises cardiac output above awake levels. Forthane does not sensitize the myocardium to exogenously administered epinephrine in the dog. Limited data indicate that subcutaneous injection of 0.25 mg of epinephrine (50 mL of 1:200,000 solution) does not produce an increase in ventricular arrhythmias in patients anesthetized with Forthane.

Muscle relaxation is often adequate for intra-abdominal operations at normal levels of anesthesia. Complete muscle paralysis can be attained with small doses of muscle relaxants. All commonly used muscle relaxants are markedly potentiated with Forthane, the effect being most profound with the nondepolarizing type. Neostigmine reverses the effect of nondepolarizing muscle relaxants in the presence of Forthane. All commonly used muscle relaxants are compatible with Forthane.

Forthane can produce coronary vasodilation at the arteriolar level in selected animal models; the drug is probably also a coronary dilator in humans. Forthane, like some other coronary arteriolar dilators, has been shown to divert blood from collateral dependent myocardium to normally perfused areas in an animal model (“coronary steal”). Clinical studies to date evaluating myocardial ischemia, infarction and death as outcome parameters have not established that the coronary arteriolar dilation property of Forthane is associated with coronary steal or myocardial ischemia in patients with coronary artery disease

Forthane is a general inhalation anesthetic used for induction and maintenance of general anesthesia. It induces muscle relaxation and reduces pains sensitivity by altering tissue excitability. It does so by decreasing the extent of gap junction mediated cell-cell coupling and altering the activity of the channels that underlie the action potential.

Forthane
Uses
Dosage
Side Effect
Precautions
Interactions
Uses during Pregnancy
Uses during Breastfeeding
Accute Overdose
Food Interaction
Half Life
Volume of Distribution
Clearance
Interaction With other Medicine
Contradiction
Storage

Trade Name	Forthane
Availability	Prescription only
Generic	Isoflurane
Isoflurane Other Names	Isoflurane, Isoflurano, Isofluranum
Related Drugs	fentanyl, lidocaine, ketamine, hyoscyamine, propofol, glycopyrrolate
Type
Formula	C₃H₂ClF₅O
Weight	Average: 184.492 Monoisotopic: 183.971433418
Groups	Approved, Vet approved
Therapeutic Class	General (Inhalation) anesthetics
Manufacturer
Available Country	Australia
Last Updated:	September 19, 2023 at 7:00 am

Uses

Forthane may be used for induction and maintenance of general anesthesia. Adequate data have not been developed to establish its application in obstetrical anesthesia.

Forthane is also used to associated treatment for these conditions: Induction and Maintenance of General Anesthesia

How Forthane works

Forthane induces a reduction in junctional conductance by decreasing gap junction channel opening times and increasing gap junction channel closing times. Forthane also activates calcium dependent ATPase in the sarcoplasmic reticulum by increasing the fluidity of the lipid membrane. Also appears to bind the D subunit of ATP synthase and NADH dehydogenase. Forthane also binds to the GABA receptor, the large conductance Ca²⁺ activated potassium channel, the glutamate receptor and the glycine receptor.

Dosage

Forthane dosage

Premedication: Premedication should be selected according to the need of the individual patient, taking into account that secretions are weakly stimulated by Forthane, and the heart rate tends to be increased. The use of anticholinergic drugs is a matter of choice.

Inspired Concentration: The concentration of Forthane being delivered from a vaporizer during anesthesia should be known. This may be accomplished by using:

Vaporizers calibrated specifically for Forthane;

Vaporizers from which delivered flows can be calculated, such as vaporizers delivering a saturated vapor, which is then diluted. The delivered concentration from such a vaporizer may be calculated using the formula: % Forthane = 100 PvFv/FT(PA- PV)

Where:

PA= Pressure of atmosphere
PV= Vapor pressure of Forthane
FV= Flow of gas through vaporizer (mL/min)
FT= Total gas flow (mL/min)

Forthane contains no stabilizer. Nothing in the agent alters calibration or operation of these vaporizers.

Induction: Induction with Forthane in oxygen or in combination with oxygen-nitrous oxide mixtures may produce coughing, breath holding, or laryngospasm. These difficulties may be avoided by the use of a hypnotic dose of an ultra-short-acting barbiturate. Inspired concentrations of 1.5 to 3.0% Forthane usually produce surgical anesthesia in 7 to 10 minutes.

Maintenance: Surgical levels of anesthesia may be sustained with a 1.0 to 2.5% concentration when nitrous oxide is used concomitantly. An additional 0.5 to 1.0% may be required when Forthane is given using oxygen alone. If added relaxation is required, supplemental doses of muscle relaxants may be used.

The level of blood pressure during maintenance is an inverse function of Forthane concentration in the absence of other complicating problems. Excessive decreases may be due to depth of anesthesia and in such instances may be corrected by lightening anesthesia.

Side Effects

Nausea, Vomiting, Shivering, Dose-dependent hypotension, Arrhythmias, Malignant hyperthermia (rare), Elevations in white blood count, May decrease creatinine and increase BUN, Ileus, severe (fatal), Hepatic dysfunction (postoperative period),Respiratory depression may occur

Toxicity

LC50=15300 ppm/3 hrs (inhalation by rat)

Precaution

Perioperative hyperkalaemia; raised intracranial pressure. May impair ability to drive or operate machinery. Pregnancy and lactation. Do not allow carbon dioxide absorbents in anaesthetic apparatus to dry out when delivering isoflurane to minimise the risk of developing elevated carboxyhaemoglobin levels.

Interaction

Enhances effects of neuromuscular blockers. May sensitise the myocardium to adrenaline and other sympathomimetics. Enhances hypotensive effects of ACE inhibitors, TCAs, MAOIs, antihypertensives, antipsychotics or beta-blockers. May have synergistic effects with CNS depressants.

Food Interaction

No interactions found.

Forthane Drug Interaction

Major: epinephrine, epinephrineUnknown: aspirin, aspirin, charcoal, charcoal, Allergy , Allergy , ciprofloxacin, ciprofloxacin, sodium iodide, sodium iodide, acetaminophen, acetaminophen, valproic acid, valproic acid, cyanocobalamin, cyanocobalamin, cholecalciferol, cholecalciferol

Pregnancy & Breastfeeding use

Pregnancy Category C. Forthane has been shown to have a possible anesthetic-related fetotoxic effect in mice when given in doses 6 times the human dose. There are no adequate and well-controlled studies in pregnant women. Forthane should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Forthane is administered to a nursing woman.

Contraindication

Known or suspected susceptibility to malignant hyperthermia. Porphyria.

Storage Condition

Store at room temperature 15°-30°C. Forthane contains no additives and has been demonstrated to be stable at room temperature for periods in excess of five years.