Trihexyphenidyl 2mg Tablets
SUMMARY OF PRODUCT CHARACTERISTICS
1 NAME OF THE MEDICINAL PRODUCT
Trihexyphenidyl 2mg Tablets
2. QUALITATIVE AND QUANTITATIVE COMPOSITION
Each tablet contains trihexyphenidyl hydrochloride 2mg For excipients, see section 6.1.
3. PHARMACEUTICAL FORM
Tablet
White flat bevelled tablets, marked MP20 on one side.
4. CLINICAL PARTICULARS
4.1. Therapeutic indications
Trihexyphenidyl is indicated in the management of the symptoms of postencephalitic arteriosclerotic and idiopathic Parkinsonism and also to control extrapyramidal disorders, which may be caused by certain drugs acting on the central nervous system, such as phenothiazines and reserpine. (These include tremor, rigidity and increased salivation, which are commonly encountered in the disease; also dyskinesia manifested by spastic contractions and involuntary movements and akathisia characterised by troublesome restlessness. Through decreasing sialorrhoea it is especially valuable as an adjunct in the treatment of arteriosclerotic Parkinsonism).
Trihexyphenidyl reduces the rigidity of muscle spasm.
4.2. Posology and method of administration
Adults:
Treatment should be initiated at a low level and gradually increased until an optimal dosage has been determined.
The usual dosage for Parkinsonism is 6-10mg per day, however patients, particularly those in the post-encephalitic group may require on average a daily dose of 12-15mg. This should be given at mealtimes either three or four times a day.
On drug-induced Parkinsonism the normal dose usually lies between 5mg and 15mg per day. Some patients have been controlled by as little as 1mg daily.
In all patients alterations in dosage either upward or downwards should only be by small increments over a period of days. At the commencement of therapy the dose should be 1mg on the first day 2mg on the second day and thereafter by increments of 2mg per day at 3-5 day intervals, continued until the optimum dose is reached.
The relationship of trihexyphenidyl therapy with meals will vary according to the reaction of the patient. If when taken after meals thirst is induced this can be allayed by chewing gum, peppermints or drinking water. Should trihexyphenidyl tend to dry the mouth excessively, it is wiser taken before meals unless nausea is troublesome.
Children:
Trihexyphenidyl is not recommended for children.
The Elderly:
Patients over 60 years of age will be more sensitive and therefore require smaller amounts of trihexyphenidyl.
Trihexyphenidyl tablets are to be taken by mouth.
4.3. Contraindications
Sensitivity to trihexyphenidyl. Trihexyphenidyl is contra-indicated for patients with glaucoma and is also contra-indicated for patients with obstructive disease of the genitourinary and gastro-intestinal tracts, particularly in patients with a history of prostatic hypertrophy and prostatism.
4.4. Special warnings and precautions for use
The patient should be under careful observation over the long term. It should be administered with care to avoid allergic or other untoward reactions.
Incipient glaucoma may be precipitated by parasympatholytic drugs such as trihexyphenidyl.
Hypertension, cardiac, liver or kidney disorders are not contra-indications, but such patients should be followed closely.
Trihexyphenidyl should be used with caution in patients with glaucoma, obstructive disease of the gastro-intestinal or genito-urinary tracts, and in elderly males with possible prostatic hypertrophy.
4.5. Interactions with other medicinal products and other forms of interaction
Addition of Impramine or Desimipramine may cause excitement, confusion and hallucinations.
4.6. Pregnancy and lactation
Problems in humans have not been documented and it is not known whether the drug is excreted in breast milk. However, lactation may be inhibited.
4.7. Effects on ability to drive and use machines
Not Applicable
4.8. Undesirable effects
Dryness of mouth, blurring of vision, dizziness, mild nausea or nervousness will be experienced by 30-50% of all patients. These reactions tend to become less pronounced as treatment continues.
Patients with arteriosclerosis or with a history of other drug idiosyncrasies may exhibit reactions of mental confusion, agitation, or nausea and vomiting. Such patients should be allowed to develop a tolerance using the smaller initial dose, with gradual increases until the effective level is reached.
4.9. Overdose
No specific antidote. Gastric lavage, emetic, high enema. Usual general treatment plus cold compresses and forcing of fluid are mandatory. Atropine antagonists may be useful.
5.1. Pharmacodynamic properties
It is believed that trihexyphenidyl acts through partially blocking central (striatal) cholinergic receptors. Trihexyphenidyl has a direct anti-spasmodic effect on smooth muscles and in small doses depresses the Central Nervous System but larger doses may cause cerebral excitation.
5.2. Pharmacokinetic properties
Absorbed in the gastro-intestinal tract with an onset of action of 1 hours and a duration of action of 6 to 12 hours.
5.3. Preclinical safety data
No relevant information additional to that contained elsewhere in the SPC.
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
Lactose monohydrate Maize starch
Pregelatinised maize starch Sodium starch glycollate Magnesium stearate
6.2. Incompatibilities
Not applicable
6.3. Shelf Life
3 years
6.4. Special Precautions for Storage
Do not store above 25°C. Store in the original container. Keep the container tightly closed.
6.5. Nature and Contents of Container
High density polystyrene tablet containers with polythene lids and/or polypropylene tablet containers with polypropylene or polythene lids and polyurethane or polythene inserts.
Pack sizes: 28, 30, 50, 56, 60, 84, 100, 250, 500 and 1000.
6.6. Instruction for Use/Handling
Not applicable
7. MARKETING AUTHORISATION HOLDER
Metwest Pharmaceuticals Limited
15 Runnelfield
Harrow on the Hill
Middlesex
HA1 3NY
United Kingdom
8. MARKETING AUTHORISATION NUMBER
PL 17521/0020
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
25/03/2009 25/03/2009