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4.3 Contraindications
Hypersensitivity to tizanidine or any other component of the product (see section 6.1 List of excipients).
The use of Zanaflex in patients with significantly impaired hepatic function is contraindicated, because tizanidine is extensively metabolised by the liver (see section 5.2 Pharmacodynamic properties).
Concomitant use of tizanidine with fluvoxamine or ciprofloxacin is contra-indicated (see section 4.5 Interaction with other medicinal products and other forms of interaction and section 4.4 Special warnings and special precautions for use).
4.4 Special Warnings and Special Precautions for Use
Concomitant use of tizanidine with CYP1A2 inhibitors is not recommended (see section 4.3 Contraindications and section 4.5 Interaction with other medicaments and other forms of interaction).
Use in Renal Impairment
Patients with renal impairment may require lower doses and therefore caution should be exercised when using Zanaflex in these patients (see section 4.2 Posology and Method of Administration
Liver Function
Hepatic dysfunction has been reported in association with Zanaflex. It is recommended that liver function tests should be monitored monthly for the first four months in all patients and in those who develop symptoms suggestive of liver dysfunction such as unexplained nausea, anorexia or tiredness. Treatment with Zanaflex should be discontinued if serum levels of SGPT and/or SGOT are persistently above three times the upper limit of normal range.
Zanaflex tablets contain lactose. This medicine is not recommended in patients with the rare hereditary problem of galactose intolerance, of severe lactase deficiency or of glucose-galactose malabsorption.
Zanaflex should be kept out of the reach and sight of children.
4.5 Interaction with other Medicinal Products and other Forms of Interaction
As Zanaflex may induce hypotension it may potentiate the effect of antihypertensive drugs, including diuretics, and caution should
therefore be exercised in patients receiving blood pressure lowering drugs. Caution should also be exercised when Zanaflex is used
concurrently with b‑adrenoceptor blocking drugs or digoxin as the combination may potentiate hypotension or bradycardia.
Caution should be exercised when Zanaflex is prescribed with drugs known to increase the QT interval.
Concomitant use of tizanidine with fluvoxamine or ciprofloxacin, both CYP450 1A2 inhibitors in man, is contraindicated. Concomitant use of tizanidine with fluvoxamine or ciprofloxacin resulted in a 33-fold and 10-fold increase in tizanidine AUC, respectively. Clinically significant and prolonged hypotension may result along with somnolence, dizziness and decreased psychomotor performance (see section 4.3 Contraindications). Co-administration of tizanidine with other inhibitors of CYP1A2 such as some antiarrhythmics (amiodarone, mexiletine, propafenone), cimetidine, some fluoroquinolones (enoxacin, norfloxacin) and ticlopidine is not recommended (see section 4.4 Special warnings and special precautions for use).
Pharmacokinetic data following single and multiple doses of Zanaflex suggested that clearance of Zanaflex was reduced by approximately 50% in women who were concurrently taking oral contraceptives. Although no specific pharmacokinetic study has been conducted to investigate a potential interaction between oral contraceptives and Zanaflex, the possibility of a clinical response and/or adverse effects occurring at lower doses of Zanaflex should be borne in mind when prescribing Zanaflex to a patient taking the contraceptive pill. Clinically significant drug-drug interactions have not been reported in clinical trials.
Alcohol or sedatives may enhance the sedative action of Zanaflex.
4.7 Effects on Ability to Drive and use Machines
Patients experiencing drowsiness and dizziness should be advised against activities requiring a high degree of alertness, e.g. driving a vehicle or operating machinery.
10. DATE OF (PARTIAL) REVISION OF THE TEXT
19.12.2006 Will be date of MHRA approval
11/07/2007
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