Chlorzoxazone is a centrally acting muscle relaxant that is used as an adjunct to physcical therapy, exercise/ rest, and analgesics to treat spasticity and acute painful musculoskeletal conditions.
Chlorzoxazone Dose in Adults
For the treatment of spasticity and painful Musculoskeletal conditions:
- 250 to 500 mg to a maximum of 750 mg three to four times each day.
- When the symptoms are better, the dose should be decreased.
Chlorzoxazone Dose in Children
For the treatment of Muscle spasm in children and adolescents:
- 20 mg/kg/day in 3 or 4 divided doses.
- The usual initial dose ranges between 125 to 250 mg thrice daily to a maximum daily dose of 750 mg/dose
Note: Because there are safer and more efficient alternatives available, it is not frequently used to treat spasticity in children with cerebral palsy as it is in patients with the condition.
Pregnancy Risk Factor: C
It has not yet been tested in pregnant women.
Use while breastfeeding
- It is unknown whether chlorzoxazone can be excreted into breastmilk.
- It is best to use it with caution.
- The nneonate should be monitored for somnolence, liver toxicities and other symptoms.
Chlorzoxazone Dose in Renal Disease:
- The manufacturer has not recommended any dose adjustment in patients with renal disease.
Chlorzoxazone Dose in Liver Disease:
- The manufacturer has not recommended any dose adjustment in patients with liver disease.
Common Side Effects of Chlorzoxazone:
-
- Central nervous system:
- Dizziness
- Drowsiness
- Malaise
- Paradoxical central nervous system stimulation
- Genitourinary:
- Urine discoloration
Contraindication to Chlorzoxazone include:
- Allergy to any drug or component of the formulation
Warnings and Precautions
- Depression in the CNS:
- Chlorzoxazone can cause CNS depression and physical and mental impairments. Patients who need mental alertness for tasks should not use chlorzoxazone.
- Hepatotoxicity
- It has been reported that liver toxicity can sometimes prove fatal.
- If symptoms of liver toxicities like anorexia and jaundice, fever, fatigue, dark urine color or right upper quadrant pain, it should be stopped immediately
- If liver enzymes become abnormal, therapy should be stopped.
- Hypersensitivity reaction
- Itching and rash caused by allergic reactions should be stopped immediately.
Chlorzoxazone: Drug Interaction
Note: Drug Interaction Categories:
- Risk Factor C: Monitor When Using Combination
- Risk Factor D: Consider Treatment Modification
- Risk Factor X: Avoid Concomitant Use
Notice: Drug Interaction Categories
Risk Factor C (Monitor therapy). |
|
| Alcohol (Ethyl). | CNS Depressants can increase the CNS depressant effects of Alcohol (Ethyl). |
| Alizapride | CNS Depressants may increase the CNS depressant effects. |
| ARIPiprazole | ARIPiprazole serum levels may rise in the presence of weak CYP3A4 inhibitors. It's crucial to keep an eye out for any heightened pharmacologic effects of aripiprazole. Depending on the indication and/or concurrent medication, aripiprazole dosage modifications may be required. See the interaction monograph in its entirety for more details. |
| Botulinum Toxin-Containing Product | The adverse/toxic effects of Botulinum Toxin-Containing products may be exacerbated by centrally acting muscle relaxants. In particular, increased muscle weakness could be a possibility. |
| Brexanolone | CNS Depressants can increase the CNS depressant effects of Brexanolone. |
| Brimonidine | CNS Depressants may increase the CNS depressant effects. |
| Bromopride | CNS Depressants may increase the CNS depressant effects. |
| Cannabidiol | CNS Depressants may increase the CNS depressant effects. |
| Cannabis | CNS Depressants may increase the CNS depressant effects. |
| Chlorphenesin Carbamate | CNS Depressants may have an adverse/toxic effect that can be exacerbated by them. |
| CNS Depressants | Can increase the toxic/adverse effects of CNS Depressants. |
| Dimethindene (Topical) | CNS Depressants may increase the CNS depressant effects. |
| Disulfiram | Might increase serum Chlorzoxazone concentrations. |
| Dofetilide | Dofetilide may be increased by CYP3A4 inhibitors (Weak). |
| Doxylamine | CNS Depressants may have a greater depressant effect on the brain. Management: Diclegis (doxylamine/ pyridoxine), which is intended for pregnancy, clearly states that it should not be used with any other CNS depressants. |
| Dronabinol | CNS Depressants may increase the CNS depressant effects. |
| Esketamine | CNS Depressants may increase the CNS depressant effects. |
| Flibanserin | Flibanserin may be increased by CYP3A4 inhibitors (Weak). |
| HydrOXYzine | CNS Depressants may increase the CNS depressant effects. |
| Isoniazid | Could increase serum levels of Chlorzoxazone. Isoniazid can decrease the serum level of Chlorzoxazone. It may also decrease the baseline chlorzoxazone concentrations after discontinuation of isoniazid. |
| Kava Kava | CNS Depressants may have an adverse/toxic effect that can be exacerbated by them. |
| Lofexidine | CNS Depressants may have a greater depressant effect on the brain. Management: Separate drug interaction monographs are available for drugs listed as an exception to this monograph. |
| Magnesium Sulfate | CNS Depressants may increase the CNS depressant effects. |
| MetyroSINE | MetyroSINE may have a sedative effect that can be enhanced by CNS depressants. |
| Minocycline | CNS Depressants may increase the CNS depressant effects. |
| Mirtazapine | CNS Depressants can increase the CNS depressant effects of Mirtazapine. |
| Nabilone | CNS Depressants may increase the CNS depressant effects. |
| NiMODipine | NiMODipine serum levels may rise in response to weak CYP3A4 inhibitors. |
| Piribedil | CNS Depressants could increase the CNS depressant effects of Piribedil. |
| Pramipexole | Pramipexole may have a greater sedative effect if it is combined with CNS depressants. |
| ROPINIRole | CNS Depressants can increase the sedative effects of ROPINIRole. |
| Rotigotine | CNS Depressants can increase the sedative effects of Rotigotine. |
| Rufinamide | CNS Depressants may have an adverse/toxic effect that can be exacerbated by this. Particularly, dizziness and sleepiness may be increased. |
| Selective Serotonin Reuptake inhibitors | CNS Depressants can increase the toxic/adverse effects of Selective Serotonin Resuptake Inhibitors. Particularly, psychomotor impairment could be increased. |
| Tetrahydrocannabinol | CNS Depressants may increase the CNS depressant effects. |
| Tetrahydrocannabinol, and Cannabidiol | CNS Depressants may increase the CNS depressant effects. |
| Trimeprazine | CNS Depressants may increase the CNS depressant effects. |
Risk Factor D (Consider therapy modifications) |
|
| Blonanserin | CNS Depressants can increase the CNS depressant effects of Blonanserin. |
| Buprenorphine | CNS Depressants can increase the CNS depressant effects of buprenorphine. Management: Reduced doses of CNS depressants should be considered and avoidance of such drugs for patients at high risk of buprenorphine self-injection/overuse. Buprenorphine patches (Butrans) should be initiated at 5 mg/hr for adults, when taken with other CNS depression drugs. |
| Chlormethiazole | Chlorzoxazone may have a depressant effect on the CNS. Chlormethiazole can increase Chlorzoxazone serum concentrations. When combined with chlormethiazole, reduce the dose of chlorzoxazone. If these agents are used together, monitor patients for elevated chlorzoxazone toxicities/effects (i.e. CNS depression, sedation). |
| Droperidol | CNS Depressants may increase the CNS depressant effects. Management: Droperidol and other CNS agents, such as opioids, may be reduced or used in combination with droperidol. Separate drug interaction monographs provide more detail on exceptions to this monograph. |
| Flunitrazepam | CNS Depressants can increase the CNS depressant effects of Flunitrazepam. |
| HYDROcodone | CNS Depressants can increase the CNS depressant effects of HYDROcodone. When possible, avoid concomitant use with hydrocodone and other CNS depressants. Combining these agents is not recommended unless there are other options. Limit the amount and duration of each drug when combined. |
| Lomitapide | CYP3A4 inhibitors may result in a rise in lomitapide (Weak). Treatment: Individuals who are currently taking lomitapide 5 mg/day can keep doing so. Individuals must cut their lomitapide dosage in half if they are taking 10 mg or more per day. The lomitapide dosage can then be changed to 30 mg/day for adults. |
| Methotrimeprazine | Methotrimeprazine may have a higher CNS depressant activity than CNS Depressants. Methotrimeprazine can increase the CNS depressant effects of CNS Depressants. Management: Lower the adult dose of CNS Depressants by 50% and start concomitant methotrimeprazine treatment. After clinically proven efficacy of methotrimeprazine, further CNS depressant dose adjustments should only be made. |
| Opioid Agonists | CNS Depressants can increase the CNS depressant effects of Opioid Aggonists. Management: When possible, avoid concomitant use opioid agonists, benzodiazepines, or other CNS depressionants. Combining these agents is not recommended unless there are other options. Limit the amount and duration of each drug when combined. |
| OxyCODONE | CNS Depressants can increase OxyCODONE's CNS depressant effects. When possible, avoid the simultaneous use of oxycodone and other CNS depressants. Combining these agents is not recommended unless there are other options. Limit the amount and duration of each drug when combined. |
| Perampanel | CNS Depressants may have a greater CNS depressant effect. Perampanel and any other CNS depressant drug should be used in combination. Patients who take perampanel together with any other drug should not engage in complex or high-risk activities until they have had experience with the combination. |
| Sodium Oxybate | CNS Depressants may have a greater depressant effect if taken in combination. Management: Look for alternatives to the combination use. If you must combine use, reduce the doses of any one or more drugs. It is not recommended to combine sodium oxybate and alcohol, or any sedative hypnotics. |
| Suvorexant | CNS Depressants can increase the CNS depressant effects of Suvorexant. Management: Suvorexant or any other CNS depressionant can be reduced in doses. Suvorexant should not be taken with alcohol. It is also not recommended to take suvorexant along with any other drugs for insomnia. |
| Tapentadol | CNS Depressants may increase the CNS depressant effects. Tapentadol, benzodiazepines and other CNS depressants should be avoided when possible. Combining these agents is not recommended unless there are other options. Limit the amount and duration of each drug when combined. |
| Tolperisone | Centrally acting muscle relaxants may have more harmful or toxic effects. When tolperisone is used with centrally acting muscle relaxants, monitoring should be done to look for any changes in sedation or CNS effects. You might need to lower the tolperisone dosage if you're using these medications together. |
| Zolpidem | CNS Depressants can increase the CNS depressant effects of Zolpidem. Management: For men who also take CNS depressants, reduce the adult Intermezzo brand sublingual Zolpidem dose to 1.75mg. For women, no dose adjustment is advised. Avoid using CNS depressants at night; do not use alcohol. |
Risk Factor X (Avoid the combination) |
|
| Azelastine - Nasal | CNS Depressants could increase the CNS depressant effects of Azelastine. |
| Bromperidol | CNS Depressants may increase the CNS depressant effects. |
| Orphenadrine | Orphenadrine may be more effective against CNS depression than other drugs. |
| Oxomemazine | CNS Depressants may increase the CNS depressant effects. |
| Paraldehyde | Paraldehyde may be enhanced by CNS depressants. |
| Pimozide | Pimozide may be increased by CYP3A4 inhibitors (Weak). |
| Thalidomide | CNS Depressants can increase Thalidomide's CNS depressant effects. |
Monitoring Parameters:
- Monitor for clinical features of hepatotoxicity and periodic liver function tests.
How to Administer Chlorzoxazone?
- Administer the drug orally after meals.
Mechanism of action of Chlorzoxazone:
- It acts centrally on the spinal cord and subcortical brain areas.
- It works by inhibiting the polysynaptic reflexes that are involved in skeletal muscle contractions and is used to treat muscle spasms.
The Beginning of ActionIt takes less than an hour and can last up to six hours.
It happens quicklyIntakeAndMetabolizedThe liver is the main source of this substance.
It has a half life of approximately one hour, and peak plasma concentration takes 1-2 hours. It is excreted through urine
International Brands of Chlorzoxazone:
- Chlorzox
- Escoflex
- Klorzoxazon
- Matalmin
- Muscol
- Myoflex
- Paraflex
- Parafon DSC
- Parafon Forte
- Prolax
- Reumophan Alka
- Reumophan Vit
- Salalin
- Sola
- Solaxin
- Tafirol Flex
Chlorzoxazone Brands in Pakistan:
|
Chlorzoxazone [Caps 250 mg] |
|
| DELZONE | DELTA PHARMA (PVT) LTD. |
 Injection.webp)