Drug Class Description

Generic Name

Drug Description

Presentation

Indications

Adult Dosage

For oral administration.

Not recommended for infants less than 2 years old

Urticaria and pruritus

Adults: 10mg (approx. 6.5ml) two or three times daily; up to 100mg per day have been used in intractable cases.

Elderly: dosage should be reduced to 10 mg (approx. 6.5ml) once or twice daily.

Children over 2 years of age : 2.5-5 mg (approx. 1.7 – 3.3ml) three or four times daily

As a sedative before anaesthesia

(Children aged 2-7 years:) the maximum dosage recommended is 2mg (approx. 1.3ml) per kg bodyweight 1-2 hours before the operation.

Child Dosage

Elderly Dosage

Contra Indications

Vallergan should be avoided in patients with hepatic or renal dysfunction, epilepsy, Parkinson's disease, hypothyroidism, phaeochromocytoma, myasthenia gravis, prostatic hypertrophy. It should be avoided in patients known to be hypersensitive to phenothiazines or to any of the excipients or with history of narrow angle glaucoma.

Special Precautions

Precautions for use:

 Vallergan should be used with caution in:

• elderly or volume depleted patients who are more susceptible to orthostatic hypotension
• Elderly patients presenting chronic constipation (risk of paralytic ileus),
• Elderly patients with possible prostatic hypertrophy
• Elderly patients in hot and cold weather (risk of hyper/hypothermia)
• patients with certain cardiovascular diseases, due to the tachycardia-inducing and hypotensive effects of phenothiazines

Patients are strongly advised not to consume alcoholic beverages or medicines containing alcohol throughout treatment.

Exposure to sunlight should be avoided during treatment. 

The sugar content should be considered in patients with diabetes or on low-sugar diets.

This medicine contains sulphites that may cause or exacerbate anaphylactic reactions.

There is a risk of post-operative restlessness especially if the child is in pain.

Interactions

The sedative effects of phenothiazines may be intensified (additively) by alcohol, anxiolytics & hypnotics, opiates, barbiturates and other sedatives. There may be increased antimuscarinic and sedative effects of phenothiazines with tricyclic antidepressants & MAOI's (including moclobemide). Respiratory depression may occur.

The hypotensive effect of most antihypertensive drugs especially alpha adrenoreceptor blocking agents may be exaggerated by phenothiazines.

The use of antimuscarinics will increase the risk of antimuscarinic side effects when used in conjunction with antihistamines.

The mild anticholinergic effect of phenothiazines may be enhanced by other anticholinergic drugs possibly leading to constipation, heat stroke, etc

The action of some drugs may be opposed by phenothiazines; these include amfetamine, levodopa, clonidine, guanethidine, adrenaline.

Anticholinergic agents may reduce the antipsychotic effect of phenothiazines.

Some drugs interfere with absorption of phenothiazines: antacids, anti-Parkinson, lithium. Increases or decreases in the plasma concentrations of a number of drugs, eg propranolol, phenobarbital have been observed but were not of clinical significance.

High doses of phenothiazines reduce the response to hypoglycaemic agents, the dosage of which may have to be raised. Adrenaline must not be used in patients overdosed with phenothiazines.

Adverse Reactions

Minor side-effects are nasal stuffiness, dry mouth, insomnia, agitation.

Liver function: Jaundice, usually transient, occurs in a very small percentage of patients. A premonitory sign may be a sudden onset of fever after one to three weeks of treatment followed by the development of jaundice. Neuroleptic jaundice has the biochemical and other characteristics of obstructive jaundice and is associated with obstructions of the canaliculi by bile thrombi; the frequent presence of an accompanying eosinophilia indicates the allergic nature of this phenomenon. Treatment should be withheld on the development of jaundice.

Cardiorespiratory: hypotension, or pallor may occur in children. Elderly or volume depleted subjects are particularly susceptible to postural hypotension.

Cardiac arrhythmias, including atrial arrhythmia. A-V block, ventricular tachycardia and fibrillation have been reported during therapy, possibly related to dosage. Pre- existing cardiac disease, old age, hypokalaemia and concurrent tricyclic antidepressants may predispose. ECG changes, usually benign, include widened QT interval, ST depression, U-waves and T-wave changes.

Respiratory depression is possible in susceptible patients.

Blood picture: A mild leukopaenia occurs in up to 30% of patients on prolonged high dosage. Agranulocytosis may occur rarely; it is not dose related. The occurrence of unexplained infections or fever requires immediate haematological investigation.

Extrapyramidal: Acute dystonias or dyskinesias, usually transitory are commoner in children and young adults and usually occur within the first 4 days of treatment or after dosage increases.

- akathisia characteristically occurs after large doses.

- Parkinsonism is commoner in adults and the elderly. It usually develops after weeks or months of treatment. One or more of the following may be seen: tremor, rigidity, akinesia or other features of Parkinsonism. Commonly just tremor.

- tardive dyskinesia: If this occurs it is usually, but not necessarily, after prolonged or high dosage. It can even occur after treatment has been stopped. Dosage should therefore be kept low whenever possible.

Skin and eyes: contact skin sensitisation is a serious but rare complication in those frequently handling preparations of phenothiazines: Care must be taken to avoid contact of the drug with the skin. Skin rashes of various kinds may also be seen in patients treated with the drug. Patients on high dosage may develop photosensitivity in sunny weather and should avoid exposure to direct sunlight. Ocular changes and the development of a metallic greyish-mauve colouration of exposed skin have been noted in some individuals, mainly females, who have received chlorpromazine continuously for long periods (four to eight years).

Endocrine: hyperprolactinaemia which may result in galactorrhoea, gynaecomastia, amenorrhoea: impotence.

Neuroleptic malignant syndrome (hyperthermia, rigidity, autonomic dysfunction and altered consciousness) may occur.

Paradoxical excitement has been noted.

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