Etrobax Mr

Uses

Etoricoxib is used for relief of pain and inflammation in-

• Osteoarthritis
• Rheumatoid arthritis
• Other chronic musculoskeletal disorders
• Acute gout
• Dysmenorrhoea
• Following dental surgery

Thiocolchicoside is a semi-synthetic colchicine derivative used as an analgesic and anti-inflammatory.

Thiocolchicoside is a skeletal muscle-relaxant drug used in the treatment of orthopedic, traumatic and rheumatologic disorders . It is indicated as an adjuvant drug in the treatment of painful muscle contractures and is indicated in acute spinal pathology, for adults and adolescents 16 years of age and older . Recent studies have examined its effect on muscle tone, stiffness, contractures, and soreness experienced by athletes during sporting competitions .

Etrobax Mr is also used to associated treatment for these conditions: Ankylosing Spondylitis (AS), Gouty Arthritis, Osteoarthritis (OA), Rheumatoid Arthritis, Moderate PainBack Pain, Acute, Chronic Back Pain, Extra-Articular Rheumatism, Muscle Inflammation, Muscle Spasms, Musculoskeletal Pain, Nonspecific Pain Post Traumatic Injury, Osteoarthritis (OA), Pain, Post Surgical Pain, Post-traumatic pain, Postoperative pain, Rheumatoid Arthritis, Soreness, Muscle, Spasms, Spinal pain, Vertebral column pain, Inflammation localized, Localized pain, Mild to moderate pain, Musculoskeletal spasms

How Etrobax Mr works

Like any other COX-2 selective inhibitor Etoricoxib selectively inhibits isoform 2 of cyclo-oxigenase enzyme (COX-2), preventing production of prostaglandins (PGs) from arachidonic acid.

Thiocolchicoside, is a synthetic sulfur derivative of colchicoside, a naturally occurring glucoside contained in the Colchicum autumnale plant. Thiocolchicoside has a selective and potent affinity for g-aminobutyric acid A (GABA-A) receptors and acts on muscular contractures by activating the GABA inhibitory pathways thereby behaving as a potent muscle relaxant . Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex . GABAergic neurons are involved in myorelaxation, anxiolytic treatment, sedation, and anesthetics. GABA can also modulate heart rate and blood pressure.

It also has an affinity for the inhibitory glycine receptors (i.e., have glycomimetic and GABA mimetic activity), therefore acts as a muscle relaxant. Glycine is an inhibitory neurotransmitter and acts as an allosteric regulator of NMDA (N-methyl-D-aspartate) receptors. It is involved in the processing of motor and sensory data, thereby regulating movement, vision, and audition. Inhibitory neurotransmitter in spinal cord, allosteric regulator of NMDA receptors .

In one study, thiocolchicoside inhibited the function of recombinant human strychnine-sensitive glycine receptors composed of the alpha1 subunit with a potency (median inhibitory concentration of 47 microM) lower than that apparent with recombinant GABA(A) receptors. The drug also inhibited the function of human nicotinic acetylcholine receptors made of the alpha4 and beta2 subunits, however, this effect was partial and moreover only apparent at high concentrations. Thiocolchicoside demonstrated no effect on the function of 5-HT(3A) serotonin receptors .

Dosage

Etrobax Mr dosage

The recommended dose for adult and patient over 16 years:

• Acute pain: 120 mg once daily. Etoricoxib 120 mg should be used only for acute symptomatic period, limited to a maximum of 8 days treatment.
• Chronic musculoskeletal pain: 60 mg once daily.
• Osteoarthritis: 30 mg once daily, increased if necessary to 60 mg once daily.
• Rheumatoid arthritis and ankylosing spondylitis: 90 mg once daily.
• Acute gout: 120 mg once daily for max. 8 days. Max. 60 mg daily in mild hepatic impairment; max. 60 mg on alternate days or 30 mg once daily in moderate hepatic impairment.

Side Effects

Dry mouth, taste disturbance, mouth ulcer, flatulence, constipation, appetite and weight changes, chest pain , fatigue, paraesthesia, influenza like syndrome, myalgia etc. may occur.

Toxicity

This reduced activity is the cause of reduced gastrointestinal toxicity, as demonstrated in several large clinical trials performed with different COXIB (see below links on NEJM and The Lancet). Some clinical trials and meta-analysis showed that treatment with COXIB lead to increased incidence of cardiovascular adverse events compared to placebo

Has been shown to cause chromosomal aneuploidy and male infertility. Should be avoided during all stages of pregnancy, lactation and puberty. Is a potential risk factor for cancer.

In 2013, The European Medical Association (EMA) mandated that the use of thiocolchicoside-containing medicines by mouth or injection should be restricted across the European Union (EU). These drugs are now recommended only as an add-on treatment for painful muscle contractures resulting from spinal conditions in adults and adolescents 16 years old and older. Additionally, the dose of thiocolchicoside by mouth or injection should be limited. This is due to experimental evidence suggesting that thiocolchicoside was metabolized into M2 or SL59.0955, that has the propensity to damage dividing cells, resulting in aneuploidy (an abnormal number or arrangement of chromosomes). As a result, the CHMP (committee for medicinal products for human use) examined the safety profile of this medicine and consider what regulatory action might be appropriate .

The CHMP reviewed the evidence, with consideration of opinions from experts in medicines safety, and concluded that aneuploidy may occur with M2 at levels not significantly greater than those measured after recommended doses of thiocolchicoside ingested orally. Aneuploidy is a strong risk factor for fetal harm, decreased fertility in men, and could theoretically increase the risk of developing cancer .

The maximum recommended oral dose is 8 mg every 12 hours; treatment length should not exceed 7 consecutive days. When given intramuscularly (IM), the maximum dose is 4 mg every 12 hours, for a maximum of 5 days .

In addition to the above toxicity, a study was done on the hepatotoxic potential of thiocolchicoside. It was observed that serum AST and ALT levels increased following of the administration oral thiocolchicoside at 8 mg/day. Two weeks after discontinuing thiocolchicoside therapy, liver enzymes had decreased to levels within the normal range. Although infrequent, thiocolchicoside should be considered a rare hepatotoxic agent in clinical practice .

Precaution

A patient with decreased liver & kidney function, dehydration, hypertension, heart failure, GI perforation & patients over 65 years of age. Use in Pregnancy and Lactation As with other drugs known to inhibit prostaglandin synthesis, use of it should be avoided in late pregnancy because it may cause premature closure of the ductus arteriosus. It should be used during the first two trimesters of pregnancy only if the potential benefit justifies the potential risk to the foetus. It is not known whether this drug is excreted in human milk.

Interaction

Oral anticoagulants, diuretics and ACE inhibitors, Acetylsalicylic acid, Cyclosporin and Tacrolimus, Lithium, Methotrexate, oral contraceptives, Prednisone/Prednisolone, Digoxin, drugs metabolized by sulfotransferases (Ethinyl Estradiol), drugs metabolized by CYP isoenzymes, Ketoconazole, Rifampicin, and Antacids have interaction with Etoricoxib.

Volume of Distribution

The apparent volume of distribution of thiocolchicoside is estimated to be approximately 42.7 L after an intramuscular injection of 8 mg .

Elimination Route

Bioavailability is 100% following oral administration.

Oral bioavailability is ~25% After intramuscular administration, thiocolchicoside Cmax occur in 30 min and .reach values of 113 ng/mL after a 4 mg dose and 175 ng/mL after a 8 mg dose. The corresponding values of AUC are respectively 283 and 417 ng.h/mL. The pharmacologically active metabolite SL18.0740 is found at lower concentrations with a Cmax of 11.7 ng/mL occurring 5 h post administration and an AUC of 83 ng.h/mL .

After oral administration, no thiocolchicoside is detected in plasma. Only two metabolites are observed: The pharmacologically active metabolite SL18.0740 and an inactive metabolite SL59.0955. For both metabolites, maximum plasma concentrations occur 1hour after thiocolchicoside administration. After a single oral dose of 8 mg of thiocolchicoside the Cmax and AUC of SL18.0740 are about 60 ng/mL and 130 ng.h/mL respectively. For SL59.0955 these values are much lower: Cmax around 13 ng/mL and AUC ranging from 15.5 ng.h/mL (until 3h) to 39.7 ng.h/mL (until 24h) .

Half Life

22 hours

Approximately 7.7h .

Clearance

Primarily extrarenal elimination (75% of the total body clearance) .

Elimination Route

Thiocolchicoside is not eliminated unchanged, rather as one of three metabolites found in either feces (~79 %) or in urine 20%. 3- demethylcolchicine (M2) and 3-O-glucurono-demethylcolchicine (M1) are found in both urine and feces, where as di-demethylcolchicine is found only in feces .

Pregnancy & Breastfeeding use

As with other drugs known to inhibit prostaglandin synthesis, use of it should be avoided in late pregnancy because it may cause premature closure of the ductus arteriosus. It should be used during the first two trimesters of pregnancy only ifthe potential benefit justifies the potential risk to the foetus. It is not known whether this drug is excreted in human milk.

Contraindication

It is contraindicated in patients with hypersensitivity to Etoricoxib or any component of this product, congestive heart failure, patients with inflammatory bowel disease, severe hepatic dysfunction.

Acute Overdose

Symptoms: GI and cardiorenal events.

Management: Symptomatic and supportive treatment. Remove unabsorbed material from the GI tract.

Storage Condition

Store at a cool & dry place protected from light & moisture. Keep out of reach of children.

Innovators Monograph

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