SIRDALUD 4MG 30TAB

Indications

Approved Uses

Management of spasticity (e.g., due to multiple sclerosis or spinal cord injury).

Off-Label Uses

Off-label: musculoskeletal pain/spasm (e.g., chronic neck/back pain), headache disorders (e.g., migraine or tension-type), and fibromyalgia (evidence variable).

Dosage & Administration

Dosing by Condition

Spasticity (IR): start 2 mg orally every 6-8 hours as needed; increase by 2-4 mg per dose at intervals of 1-4 days; maximum 3 doses/24 hours and maximum total 36 mg/day.

Initial Dose

2 mg orally, may be repeated every 6 to 8 hours.

Maintenance Dose

Typically 8 mg to 24 mg daily in 3-4 divided doses.

Maximum Dose

36 mg per 24 hours.

Dose Adjustment Notes

Titrate gradually in 2-4 mg increments per dose with at least 1-4 days between increases; use lower doses and slower titration in renal impairment and avoid/use extreme caution in hepatic impairment; taper gradually when discontinuing (especially after higher doses/longer use) to reduce rebound hypertension/tachycardia.

How to Take

Swallow tablet whole with water; may take with or without food but take consistently the same way each time; separate doses by 6-8 hours and do not exceed 3 doses in 24 hours.

Side Effects

Common Side Effects

Dry mouth, somnolence/drowsiness, dizziness, asthenia/fatigue, hypotension (including orthostatic), and weakness.

Safety & Warnings

Contraindications

Contraindicated in: hypersensitivity to tizanidine; concomitant use with potent CYP1A2 inhibitors (especially fluvoxamine or ciprofloxacin).

Warnings & Precautions

Key warnings/precautions: monitor liver function (baseline and periodically); risk of significant hypotension/bradycardia (caution with antihypertensives and CYP1A2 inhibitors); sedation-avoid alcohol/CNS depressants and caution with driving; hallucinations may occur; taper to discontinue to avoid rebound hypertension/tachycardia; use caution and adjust dosing in renal impairment (CrCl <25 mL/min) and avoid/extreme caution in hepatic impairment.

Age Restriction

Pediatric use (<18 years): safety and effectiveness have not been established; generally not recommended unless specialist-directed.

Driving Warning

Avoid Driving

Drug Interactions

Drug Interactions

Major interactions: fluvoxamine and ciprofloxacin (contraindicated); other CYP1A2 inhibitors (e.g., cimetidine, oral contraceptives, zileuton, mexiletine) increase tizanidine levels; antihypertensives increase hypotension/bradycardia risk; CNS depressants and alcohol increase sedation/psychomotor impairment.

Interaction Severity

MAJOR/Contraindicated: fluvoxamine, ciprofloxacin (strong CYP1A2 inhibitors). MAJOR: other strong CYP1A2 inhibitors (avoid) and combinations causing profound hypotension/sedation. MODERATE: other CYP1A2 inhibitors (e.g., oral contraceptives, zileuton, mexiletine, cimetidine) and antihypertensives. ADDITIVE CNS DEPRESSION: alcohol and other CNS depressants (clinically significant; generally avoid).

Alcohol Interaction

Dangerous

Special Populations

Elderly

Start at lower dose (2mg), titrate slowly with careful monitoring of blood pressure and renal function

Kidney Impairment

CrCl <25 mL/min: use with caution; start low and titrate slowly-prefer increasing the individual dose rather than dosing frequency; monitor closely for excessive sedation/hypotension.

Liver Impairment

Hepatic impairment: avoid if possible; if used, use extreme caution with lower doses and close LFT monitoring; severe hepatic impairment-avoid/contraindicated.

Storage & Patient Advice

Missed Dose

Take as soon as remembered; skip if near the time of the next dose; do not double the dose

Stopping the Medicine

Do not stop abruptly; taper gradually (especially after high doses or prolonged use) to reduce risk of rebound hypertension and tachycardia.

Overdose

Overdose may cause marked CNS depression (somnolence/confusion/coma), bradycardia, hypotension, and possible respiratory depression; management is supportive (airway/ventilation, IV fluids, vasopressors if needed) and consider activated charcoal if early after ingestion; urgent medical evaluation required.

Patient Counseling

Take consistently with or without food; expect drowsiness/dizziness-avoid driving/operating machinery until effects are known; avoid alcohol and other sedatives; rise slowly to reduce orthostatic symptoms; do not stop abruptly-taper with prescriber guidance; report liver injury symptoms (jaundice, dark urine, persistent nausea/abdominal pain); tell clinicians about all medicines and avoid ciprofloxacin/fluvoxamine and other CYP1A2 inhibitors.

Monitoring Requirements

Monitor liver aminotransferases at baseline and periodically (commonly at ~1, 3, and 6 months, then as clinically indicated); monitor blood pressure/heart rate (especially during titration and with antihypertensives) and sedation; assess renal function in renal impairment.

Pharmacology

Mechanism of Action

Centrally acting alpha-2 adrenergic agonist that increases presynaptic inhibition of motor neurons in the spinal cord (reducing excitatory neurotransmitter release and polysynaptic reflex activity), thereby reducing spasticity.

Onset of Action

1-2 hours.

Duration of Effect

3-6 hours.

Half-Life

2-2.5 hours

Bioavailability

Oral absolute bioavailability is approximately 40% to 95% (low due to extensive first-pass metabolism).

Metabolism

Extensive hepatic metabolism primarily via CYP1A2 to multiple (largely inactive) metabolites.

Excretion

Mainly eliminated by the kidney.

Protein Binding

Approximately 30% (tizanidine)

Product Information

Available Dosage Forms

Immediate-release oral tablet (this SFDA product: 4 mg tablet) and oral capsule (immediate-release in some markets); an extended-release capsule exists in some markets but is not universal.

Composition per Dose

Each tablet: 4mg tizanidine (as tizanidine hydrochloride)

Generic Availability

Yes

OTC Alternatives

No OTC alternative

Pain Type

Spasticity

Nsaid

No

Opioid

No

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