Chlorzoxazone

Chlorzoxazone May be taken with or without food. May be taken w/ food/milk if stomach upset occurs.

Patient with history or known allergic reactions to drugs. Hepatic impairment. Elderly. Pregnancy and lactation.

Significant: CNS depression. Rarely, hypersensitivity reactions (e.g. rash, petechiae, ecchymoses, urticaria, pruritus, angioedema, anaphylaxis).
Gastrointestinal disorders: Nausea, vomiting, heartburn, abdominal distress, constipation, diarrhoea. Rarely, gastrointestinal bleeding.
General disorders and administration site conditions: Malaise.
Nervous system disorders: Drowsiness, dizziness, lightheadedness, headache, overstimulation.
Renal and urinary disorders: Urine discolouration.
Potentially Fatal: Rarely, serious hepatocellular toxicity.

This drug may cause drowsiness or dizziness, if affected, do not drive or operate machinery.

Monitor LFTs periodically. Assess for signs and symptoms of hepatotoxicity or hypersensitivity reactions.

Symptoms: Nausea, vomiting, diarrhea, drowsiness, dizziness, lightheadedness, headache, malaise, sluggishness, loss of muscle tone, decreased or absent deep tendon reflexes, hypotension, respiratory depression. Management: Supportive treatment. Induce emesis or perform gastric lavage, followed by activated charcoal administration. Maintain adequate airway; employ oxygen and assisted respiration, if with respiratory depression. May cautiously administer vasopressor agents (e.g. norepinephrine), dextran, plasma, or concentrated albumin to manage hypotension.

Concomitant administration with other CNS depressants may cause enhanced CNS depression. Increased plasma concentration with disulfiram. Isoniazid may increase or decrease the serum concentration of chlorzoxazone.

Additive CNS depressant effect with alcohol.

Description:
Mechanism of Action: Chlorzoxazone is a centrally acting skeletal muscle relaxant with sedative effects. It inhibits polysynaptic reflex arcs at the spinal cord and subcortical areas of the brain, leading to reduced skeletal muscle spasms, pain relief, and increased muscle mobility.
Onset: Within 1 hour.
Duration: Up to 6 hours.
Pharmacokinetics:
Absorption: Rapidly and completely absorbed from the gastrointestinal tract. Time to peak plasma concentration: Approx 1-2 hours.
Metabolism: Rapidly metabolised in the liver via glucuronidation by CYP2E1 into 6-hydroxychlorzoxazone (inactive metabolite).
Excretion: Via urine (primarily as glucuronide metabolite; <1% as unchanged drug). Elimination half-life: Approx 1 hour.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 2733, Chlorzoxazone. https://pubchem.ncbi.nlm.nih.gov/compound/Chlorzoxazone. Accessed July 29, 2024.

Store between 20-25°C.

Muscle Relaxants

M03BB03 - chlorzoxazone ; Belongs to the class of oxazol, thiazine, and triazine derivative agents. Used as centrally-acting muscle relaxants.

Anon. Chlorzoxazone. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 28/06/2024.

Brayfield A, Cadart C (eds). Chlorzoxazone. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 28/06/2024.

Chlorzoxazone Tablet (Rising Pharma Holdings, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 28/06/2024.

Chlorzoxazone. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 16/07/2024.

Chlorzoxazone. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 28/06/2024.

Lorzone Tablet (Vertical Pharmaceuticals, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 28/06/2024.