Tizanidine: Difference between revisions

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| generic = Tizanidine

| brand = Zanaflex

| classes = ~~Muscle~~ relaxant

| structure =

| mechanism = ~~Alpha~~-2 adrenergic receptor agonist

| classes = [[:Category:Skeletal muscle relaxants|Skeletal muscle relaxant (centrally-acting)]], [[:Category:Alpha-2 adrenergic agonists|Alpha-2 adrenergic agonist]], [[:Category:Antispastics|Antispastic]]

| uses = <vote slug="spasticity-multiple-sclerosis-use">Spasticity in multiple sclerosis (FDA)</vote>, <vote slug="spasticity-spinal-cord-injury-use">Spasticity in spinal cord injury (FDA)</vote>, <vote slug="spasticity-cerebral-palsy-use">Spasticity in cerebral palsy (FDA)</vote>, <vote slug="acute-musculoskeletal-pain-use">Acute musculoskeletal pain (off-label)</vote>

| starting_dose = 2 mg PO every 6-8 hours; titrate by 2-4 mg per dose every 1-4 days; maximum single dose 16 mg, maximum daily dose 36 mg

| preparations = Tablets 2, 4 mg; capsules 2, 4, 6 mg ('''capsules and tablets are not bioequivalent''': capsules slower with food; tablets faster on empty stomach)

| fda_max = 36 mg/day in three divided doses; single dose maximum 16 mg

| pill_id =

| routes = Oral

| onset = 30-60 minutes

| duration = 3-6 hours per dose

| halflife = 2.5 hours (short, requires TID-QID dosing)<ref name="zanaflex-label">FDA Prescribing Information, Zanaflex (tizanidine hydrochloride), Acorda Therapeutics, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/020397s029,021447s011lbl.pdf</ref>

| bioavailability = ~40% (oral); food and formulation substantially alter the absorption profile<ref name="zanaflex-label" />

| pregnancy = Limited human data.{{citation needed}}

| legal = [[USLegal:Prescription only|Rx-only]] in US. Not a controlled substance, distinguishing it from carisoprodol among muscle-spasm options<ref name="zanaflex-label" />

| mechanism = <vote slug="tizanidine-mech-claim">Centrally-acting α2-adrenergic receptor agonist closely related to clonidine, but with greater selectivity for spinal cord α2 receptors over peripheral α2, producing antispastic effect with somewhat less systemic hypotension and sedation than clonidine at equipotent muscle-relaxant doses. The mechanism reduces excitatory neurotransmitter release from spinal interneurons.</vote> '''CYP1A2 substrate''' with major interaction signal: fluvoxamine raises plasma exposure ~33-fold and ciprofloxacin ~10-fold, with severe hypotension reported; both combinations are '''contraindicated'''. Hepatotoxicity signal warrants baseline and periodic LFT monitoring with chronic use<ref name="zanaflex-label" />.

}}

~~[[Category:Muscle_Relaxants]]~~

== References ==

[[Category:Skeletal muscle relaxants]]

[[Category:Alpha-2 adrenergic agonists]]

[[Category:Antispastics]]

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