Anticholinergic, for the treatment of all forms of Parkinsonism, including drug induced (neuroleptic syndrome)

Adults and the elderly:

Initially, 150mg daily in divided doses, increasing by 50mg every two or three days until maximum benefit is obtained. Optimal dosage is usually 250mg to 300mg daily in divided doses in idiopathic and post-encephalitic Parkinsonism; 100mg to 150mg daily in divided doses in arteriosclerotic parkinsonism; and 150mg to 300mg daily in divided doses in the neuroleptic syndrome.

Maximal dosage is 400mg daily in divided doses. The elderly may be more susceptible to side effects at doses which are clinically optimal.

Children:

Not recommended for use in children.

Hypersensitivity to orphenadrine or to any of the Excipients.

In patients with prostatic hypertrophy, tardive dyskinesia, porphyria, urinary retention and must also be used with caution in elderly men.

Also in patients with paralytic ileus or pyloric stenosis, where use may lead to obstruction.

Do not use in patients with glaucoma or too narrow an angle between iris and cornea, as it may raise intra-ocular pressure. Not indicated for use in patients at risk of developing hyperpyrexia.

Use with caution in the elderly (see Section 4.2).

When used alone or with analgesics, pain or skeletal muscle spasms have been reported.

Use with caution in conditions characterised by tachycardia. Anti-muscarinic agents, such as orphenadrine, should be used with caution in patients with pre-existing tachycardia (e.g. in heart failure, thyrotoxicosis) as they may cause further acceleration of the heart rate.

Anti-muscarinic agents such as orphenadrine are not effective in the treatment of tardive dyskinesia which may be made worse and should not be used in patients with this condition.

Care should be taken when using in patients with concomitant hypertension, cardiac, renal or hepatic dysfunction.

Use with caution in patients with micturition difficulties and in pregnancy and breastfeeding.

Avoid abrupt discontinuation of treatment. For some patients orphenadrine may be a drug of abuse.

Excipient Warnings

• Methyl Hydroxybenzoate (E218) 6.0mg in each 5ml and Propyl Hydroxybenzoate (E216) 1.5mg in each 5ml.May cause allergic reactions (possibly delayed).Liquid Maltitol (E965) 2049mg in each 5ml. Patients with rare hereditary problems of fructose intolerance should not take this medicine. May have a mild laxative effect. Calorific value 4.7 kcal/5ml

• Benzyl Alcohol. This medicine contains 1.03mg of benzyl alcohol in each 5 ml. Benzyl alcohol may cause allergic reactions. High volumes should be used with caution and only if necessary, especially in subjects with liver or kidney impairment because of the risk of accumulation and toxicity (metabolic acidosis).

• Sorbitol (E420) 454.7mg in each 5ml. The additive effect of concomitantly administered products containing sorbitol (or fructose) and dietary intake of sorbitol (or fructose) should be taken into account.

The content of sorbitol in medicinal products for oral use may affect the bioavailability of other medicinal products for oral use administered concomitantly.

Patients with hereditary fructose intolerance (HFI) should not take/be given this medicinal product.

• Alcohol (Ethanol) 0.7mg in each 5 ml. The amount in 5 ml of this medicine is equivalent to less than 1 ml beer or 1 ml wine. The small amount of alcohol in this medicine will not have any noticeable effects.

• This medicine contains less than 1 mmol Sodium (23 mg) per 5ml, that is to say essentially 'sodium-free'.

Effects may be enhanced by concomitant administration of anticholinergic drugs. May be provocation of dextropropoxyphene side effects during concurrent administration.

As with other similar agents, the anti-muscarinic effects of orphenadrine may be enhanced by the concomitant administration of other medications with anti-muscarinic properties, such as antihistamines, antispasmodics, tricyclic antidepressants, phenothiazines, dopaminergic anti parkinsonian drugs including amantadine, and anti-arrhythmics such as disopyramide.

Although the additional effects may be minor, there is the potential for the development of severe constipation and ileus, atropine-like psychoses and heat stroke.

Due to the anti-muscarinic effects of orphenadrine on the gastrointestinal tract, a reduction in gastric motility may occur which may affect the absorption of other orally administered drugs.

Pregnancy

There is inadequate evidence of safety in human pregnancy, and, although it has been widely used for many years without apparent ill consequence, if considered necessary orphenadrine should be used with caution during pregnancy. Animal studies have not revealed any hazard.

Breast-feeding

It is probably excreted in milk during lactation. Although the quantity is unlikely to be significant at normal therapeutic doses, if considered necessary orphenadrine should be used with caution during breast feeding.

Orphenadrine may cause blurred vision or slight euphoria. If patients experience these side effects, driving or operating machinery is not recommended.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via Yellow Card Scheme at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

Toxicity:

Adults: 2 – 3 g can be fatal for an adult though patients have survived doses of 5 g and 7.5 g.

Children: A 23 month old had severe toxicity after ingesting 300mg.

Toxicity is mainly due to anticholinergic effects at autonomic nerve endings and in the brain.

Features:

Common: Nausea, vomiting, flushing, dilated pupils, dry mouth and tongue, hot dry skin, fever, sinus tachycardia, hypertension, ataxia, nystagmus, drowsiness, delirium, agitation and visual hallucinations.

Uncommon: Myoclonic jerking, coma, convulsions, cardiac conduction abnormalities and dysrhythmias, cardiovascular collapse, paralytic ileus, urinary retention.

Treatment:

Activated charcoal or gastric lavage may be of benefit if the patient presents within 1 hour of having taken a potentially toxic amount.

Forced diuresis, haemodialysis and haemoperfusion are of no benefit.

Observe the mildest cases for at least 6 hours.

Monitor for and treat the following as clinically indicated: Airway patency, arterial blood gases (hypoxia and/or hypercapnoea may require oxygen or ventilation to correct), hypothermia or hyperthermia, hypotension (intravascular volume expanders or dopamine may be required), skin blisters (treat as burns), convulsions or delirium (can be treated with diazepam).

Cardiac dysrhythmias: Resist the temptation to use antiarrythmic drugs. Correct hypoxia and administer sodium bicarbonate (even in the absence of acidosis).

ATC Code – N04A B

Pharmacotherapeutic Group: Anti-Parkinson Drugs

Orphenadrine, which is a congener of diphenhydramine without sharing its soporific effect, is an anti-muscarinic agent. It also works has weak antihistaminic and local anaesthetic properties.

Orphenadrine is used as the hydrochloride in the symptomatic treatment of Parkinsonism. It is also used to alleviate the extrapyramidal syndrome induced by drugs such as the phenothiazine derivatives, but is of no value in tardive dyskinesia, which may be exacerbated.

Orphenadrine is readily absorbed from the gastro-intestinal tract. It is rapidly distributed in tissues and most of a dose is metabolised to at least 8 metabolites and excreted in the urine along with a small proportion of unchanged drug. A half life of 14 hours has been reported.

Orphenadrine is a drug on which extensive clinical experience has been obtained. Relevant information for the prescriber is provided elsewhere in the Summary of Product Characteristics.

Methyl hydroxybenzoate, propyl hydroxybenzoate, propylene glycol, liquid maltitol, sorbitol solution 70%, saccharin sodium, blackcurrant flavour (containing, Pulegone, Benzyl Alcohol, Propylene Glycol and Ethanol), aniseed flavour, citric acid monohydrate, sodium citrate and purified water.

Incompatible with alkali, protect from light.

2 years

Store below 25° C and avoid exposure to direct sunlight. Only dispense in amber glass bottles.

Any unused product or waste material should be disposed of in accordance with local requirements.