Promethazine Theoclate

Indications

Promethazine Theoclate is an anti-emetic drug which helps to prevent, and treat nausea and vomiting, including travel sickness, and vertigo. Promethazine Teoclate Tablets contains promethazine which belongs to a group of medicines called phenothiazines. Your doctor may prescribe this medicine for giddiness or light-headedness (vertigo), or for sickness after an operation, and in such cases the tablets should be taken as instructed by your doctor.

Pharmacology

Promethazine Theoclate works by stopping histamine from binding to its receptors in 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.

By blocking the histamine receptors in the vomiting centre, Promethazine Theoclate prevents disturbances in the middle ear from activating the vomiting centre.

Dosage & Administration

Motion sickness: Adults: For prevention on long journeys: One 25 mg tablet each evening at bedtime, starting the day before setting out, the duration of action is such that a second dose in 24 hours is not often necessary.

For prevention of motion sickness on short journeys: One 25 mg tablet one or two hours before traveling or as soon after as possible.

Treatment of motion sickness: One 25mg tablet as soon as possible and repeated the same evening followed by a third tablet on the following evening.

Nausea and vomiting due to other causes: Adults: One 25mg tablet at night is often sufficient, but two or three tablets are sometimes necessary. Alternatively, more frequent administration such as 25mg two or three times a day may be required for some patients. is not often necessary to give more than four of the 25mg Avomine tablets in 24 hours.

Children: In the above indications children over 10 years of age may be given the lower adult doses described above. Children between 5 and 10 years may be given half the adults dose.

Elderly: No specific dosage recommendations.

Interaction

Avomine may enhance the action of any anticholinergic agent, tricyclic antidepressant, sedative or hypnotic. Alcohol should be avoided during treatment. Avomine may interfere with immunologic urine pregnancy tests to produce false-positive or false-negative results. Avomine should be discontinued at least 72 hours before the start of skin tests using allergen extracts as it may inhibit the cutaneous histamine response thus producing false-negative results. In nausea and vomiting of unknown origin, it is essential to establish the diagnosis before giving an anti-emetic, to ensure that serious underlying condition is not masked.

Contraindications

Do not give to a child under 2 years old. Do not take Promethazine Teoclate Tablets if you have:

ever had an allergic reaction to promethazine, any phenothiazine or any of the ingredients taken medicines for depression, known as Monoamine Oxidase Inhibitors (MAOIs) within the last 14 days CNS depression. People with CNS depression will seem sleepy or unconscious (including coma).

Take special care with Promethazine Teoclate Tablets and tell your doctor or pharmacist if you suffer with:
  • glaucoma (increased pressure in the eye)
  • epilepsy
  • heart problems
  • liver problems
  • kidney or bladder problems
  • a chest condition such as asthma or bronchitis
  • severe headaches with blurred vision, severe stomach pains with vomiting, dizziness, difficulty with keeping your balance, ringing in the ears or other ear problems as well as feeling sick
  • a bad cough
  • Reye’s Syndrome or symptoms of Reye’s Syndrome (including persistent vomiting, feeling tired or sleepiness).
Do not take Promethazine Teoclate Tablets for more than 7 days without contacting your doctor.

Side Effects

Side-effects may be seen in a few patients: drowsiness, dizziness, restlessness, headaches, night mares, tiredness and disorientation, Anticholinergic side-effects such as blurred vision, dry mouth and urinary retention occur occasionally. The elderly are particularly susceptible to the anticholinergic effects and confusion due to promethazine. Other side-effects include anorexia, gastric irritation, palpitations, hypotension, arrhythmias, extrapyramidal effects, muscle spasms and tic-like movements of the head and face. Anaphylaxis, jaundice and blood dyscrasias including haemolytic anaemia rarely occur. Photosensitive skin reactions have been reported; strong sunlight should be avoided during treatment.

Pregnancy & Lactation

Use in pregnancy: There is epidemiological evidence for the safety of promethazine in pregnancy and animal studies have shown on hazard, nevertheless it should not be used in pregnancy unless the physician considers it essential. The use of Avomine tablets is not recommended in the two weeks prior to delivery in view of the risk of irritability and excitement in the neonate.

Use in lactation: Available evidence suggests that the amount excreted in milk is insignificant. However there are risks of neonatal irritability and excitement. Ambulant patients receiving Avomine for the first time should not be in control of vehicles or machinery for the first few days until it is established that they are not hypersensitive to the central nervous effects of the drug and do not suffer from disorientation, confusion or dizziness.

Precautions & Warnings

Promethazine Theoclate tablets can make some people feel drowsy, dizzy, confused or disorientated and this 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. If your child is affected in this way they should avoid potentially hazardous activities such as riding bikes. You should not leave your child unattended after giving them this medicine.

Avoid drinking alcohol while taking Promethazine Theoclate because this is likely to make the above effects more likely or worse.

Promethazine Theoclate tablets may make your skin more sensitive to sunlight than usual, 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 Promethazine Theoclate 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.

Overdose Effects

Symptoms of severe overdosage are variable. They are characterised in children by various combinations of excitation, ataxia, inco-ordination, athetosis and hallucinations, while adults may become drowsy and lapse into coma. Convulsion may occur in both adults and children; coma or excitement may precede their occurrence. Cardiorespiratory depression is uncommon. If the patient is seen soon enough after ingestion, it should be possible to induce vomiting with ipecacuanha despite the anti-emetic effect of promethazine; alternatively, gastric lavage may be used. Treatment is otherwise supportive with attention to maintenance of adequate respiratory and circulatory status. Convulsions should be treated with diazepam or other suitable anticonvulsant.

Therapeutic Class

Anti-emetic drugs, Miscellaneous sedatives & hypnotics, Sedating Anti-histamine

Storage Conditions

Do not use later than the date of expiry Keep all medicines out of the reach of children To be dispensed only on the prescription of a registered physician.

Available Brand Names

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