Promethazine theoclate (Avomine)
How does it work?
Avomine tablets contain the active ingredient promethazine teoclate, which is a type of medicine known as an antihistamine. It is used to prevent travel sickness and nausea.
Promethazine works by preventing the action of histamine. Promethazine blocks histamine from binding to its receptors in various parts of the body, including an area in the brain known as the vomiting centre. The vomiting centre is responsible for causing feelings of sickness and for the vomiting reflex. It is activated when it receives nerve messages from the vestibular apparatus in the middle ear.
The vestibular apparatus provides constant feedback to the brain about the position of our body. When something disturbs the vestibular apparatus, such as movements of the head when travelling by boat or car, nerve signals are sent from the vestibular apparatus to the vomiting centre. This can cause the symptoms of motion sickness, such as nausea, dizziness or spinning sensations (vertigo) and vomiting.
Promethazine can be used to prevent motion sickness, because by blocking the histamine receptors in the vomiting centre, it prevents disturbances in the middle ear from activating the vomiting centre.
To prevent travel sickness on short journeys Avomine tablets need to be taken at least one or two hours before travelling. For long journeys Avomine tablets need to be taken at bedtime, starting the day before setting out.
What is it used for?
- Preventing and relieving travel sickness.
- Nausea and vomiting.
- This medicine should not be used for longer than seven days without seeking medical advice from your doctor.
- This medicine may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.
- This medicine may make your skin more sensitive to sunlight than it usually is, so you should avoid exposing your skin to direct sunlight or sunlamps until you know how your skin reacts. If you can't avoid strong sunlight you should use a sunscreen lotion or make sure your skin is protected with clothing.
- This medicine may interfere with some pregnancy tests, causing false negative or false positive results.
- If you are due to have any skin prick tests to diagnose allergies you should stop taking this medicine at least 72 hours before the tests. This is because antihistamines can prevent or lessen the skin reactions that indicate an allergy, and so can make the test results unreliable.
Use with caution in
- Closed angle glaucoma.
- Decreased kidney function.
- Decreased liver function.
- A condition called bronchiectasis in which there is persistent and progressive widening of the airways due to lung infections or lung disease, such as cystic fibrosis.
- Blockage of the opening from the stomach into the intestines (pyloro-duodenal obstruction).
- Blockage of the drainage of urine out of the bladder (bladder neck obstruction), for example due to an enlarged prostate gland.
- Severe coronary artery disease.
Not to be used in
- Children under two years of age.
- Reduced awareness, slow reactions or extreme drowsiness due to medicines or illness (depression) that reduce activity in the central nervous system .
- Comatose states.
- People who have taken a type of medicine called a monoamine-oxidase inhibitor antidepressant (MAOI) in the past 14 days.
- This medicine should be avoided in children and adolescents with signs and symptoms suggestive of Reye's Syndrome.
- Avomine tablets contain lactose and should not be taken by people with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption.
This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Pregnancy and breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
- If you are pregnant you should not take this medicine without consulting your doctor first. This medicine can be used with caution during pregnancy, but only if the expected benefit to the mother outweighs any potential risks to the developing baby. However, this medicine should not be used during the last two weeks of a pregnancy, because if taken during this time it may cause irritability or excitement in the baby after birth. Seek further medical advice from your doctor.
- Small amounts of this medicine may pass into breast milk. This is not expected to be harmful to a nursing infant, but the manufacturer states that there is a risk that it may cause irritability or excitement in a newborn baby. If you are breastfeeding you should not take this medicine without seeking first medical advice from your doctor.
- This medication may cause drowsiness. If affected do not drive or operate machinery. Avoid alcoholic drink.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.
- Blurred vision.
- Difficulty passing urine (urinary retention).
- Dry mouth.
- Unexpected increase in excitability in children.
- Rash or itching.
- Loss of appetite.
- Awareness of your heartbeat (palpitations).
- Low blood pressure (hypotension).
- Abnormal movements of the hands, legs, face, neck and tongue, eg tremor, twitching, rigidity (extrapyramidal effects).
- Blood disorders.
- Increased sensitivity of the skin to sunlight (photosensitivity). If affected you should avoid sun lamps and direct sunlight while you are taking this medicine.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.
For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start taking this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.
The manufacturer states that this medicine should not be taken by anyone who is taking a type of antidepressant called a monoamine oxidase inhibitor (MAOI), eg phenelzine, tranylcypromine, isocarboxazid, or who has taken an MAOI in the previous 14 days.
There may be an increased risk of drowsiness if this medicine is taken with any of the following (which can also cause drowsiness):
- antipsychotic medicines, eg chlorpromazine
- barbiturates, eg phenobarbital
- benzodiazepines, eg diazepam, temazepam
- sedating antihistamines, eg chlorphenamine, brompheniramine, hydroxyzine
- sleeping tablets, eg zopiclone
- strong opioid painkillers, eg morphine, codeine, dihydrocodeine
- tricyclic antidepressants, eg amitriptyline.
There may be an increased risk of side effects such as dry mouth, constipation, difficulty passing urine or confusion if promethazine is taken with other medicines that have anticholinergic effects, such as the following:
- anticholinergic medicines for Parkinson's symptoms, eg procyclidine
- antispasmodic medicines, eg hyoscine
- certain antihistamines, eg brompheniramine, chlorphenamine
- certain antipsychotic medicines, eg chlorpromazine
- certain antisickness medicines, eg prochlorperazine, meclozine, cyclizine
- medicines for urinary incontinence, eg oxybutynin, flavoxate, tolterodine, propiverine, trospium
- muscle relaxants, eg baclofen
- MAOI antidepressants, eg phenelzine
- tricyclic antidepressants, eg amitriptyline.
This medicine may counteract the effect of betahistine.
Other medicines containing the same active ingredients
There are currently no other medicines available in the UK that contain promethazine teoclate as the active ingredient.