Halosin

Indications

Halothane is an inhaled general anaesthetic. It is used to start and keep up general anaesthesia (a controlled, deep sleep) during surgery and other procedures. Because newer agents are available, it is now used less often, but it is still used in some hospitals, including for children.

How It Works

Halothane is a liquid that turns into vapour. When breathed in through a mask or breathing tube, it passes from the lungs into the blood and then to the brain, where it dampens nerve signalling. This causes loss of consciousness and of awareness of pain. When the vapour is switched off, it is breathed out and the person slowly wakes up.

Dosage and Administration

Halothane is given only by an anaesthetist in an operating theatre, using a special calibrated vaporiser and anaesthetic machine. The concentration is set and adjusted by the anaesthetist according to the patient's age, condition and the stage of the operation. It is never used at home.

Interactions

Halothane makes the heart more sensitive to Adrenaline (Epinephrine) and similar drugs, which can cause dangerous heart rhythm problems. It adds to the effects of opioid painkillers, sedatives and muscle relaxants. Beta blockers, Aminophylline and some antibiotics may also interact. Tell the anaesthetist about all medicines you take.

Contraindications

Halothane should not be used in people who had unexplained jaundice, fever or liver problems after a previous halothane anaesthetic, in people with a personal or family history of malignant hyperthermia (a rare, dangerous reaction to anaesthetics), or when it is unsuitable for other reasons judged by the anaesthetist.

Side Effects

Common effects include low blood pressure, slow heartbeat, shallow breathing, shivering, nausea and vomiting on waking. Irregular heart rhythm can occur. Rarely, it causes serious liver inflammation (halothane hepatitis), more often after repeated exposure in adults.

After the operation, get urgent medical help for yellow skin or eyes, dark urine, high fever, severe stomach pain, confusion or breathing problems. During anaesthesia, the team watches for and treats serious reactions straight away.

Pregnancy and Lactation

Halothane relaxes the womb and may increase bleeding during childbirth or caesarean section, so other agents are usually preferred in pregnancy and labour. Only small amounts reach breast milk; breastfeeding can usually resume once the mother is awake and alert, as advised by the doctor.

Precautions and Warnings

Heart rate, blood pressure, oxygen level and breathing are monitored throughout. Repeat use within a short period is avoided because of the liver risk. Care is needed in people with liver disease, heart rhythm problems or raised pressure inside the head. Do not drive or operate machinery for at least 24 hours after a general anaesthetic.

Overdose

Too much halothane causes very low blood pressure, slow heart rate and stopped breathing. The anaesthetist turns off the vapour, gives oxygen and supports breathing and circulation.

Therapeutic Class

General anaesthetic (inhaled, halogenated hydrocarbon).

Storage

Store as directed on the pack, usually below 25°C in a tightly closed, light-resistant bottle. Hospital use only; keep out of the reach of children.