Duofix

Uses

It is used for the relief of signs and symptoms of osteoarthritis, rheumatoid arthritis and ankylosing spondylitis and to decrease the risk of developing gastric ulcers in patients at risk of developing NSAID associated gastric ulcers. Esomeprazole & Naproxen combination is not recommended for initial treatment of acute pain because the absorption of naproxen is delayed compared to absorption from other naproxencontaining products. Controlled studies do not extend beyond 6 months.

Duofix is also used to associated treatment for these conditions: Duodenal Ulcer, Erosive Esophagitis, Gastro-esophageal Reflux Disease (GERD), Heartburn, Helicobacter Pylori Infection, NSAID Associated Gastric Ulcers, Stress Ulcers, Upper Gastrointestinal Hemorrhage, Zollinger-Ellison Syndrome, Acute benign gastric ulcers, Maintenance of healing Erosive esophagitis, Postendoscopy BleedingAcute Gouty Arthritis, Acute Migraine, Ankylosing Spondylitis (AS), Arthritis, Backache, Bursitis, Extra-Articular Rheumatism, Fever, Flu caused by Influenza, Headache, Juvenile Idiopathic Arthritis (JIA), Menstrual Distress (Dysmenorrhea), Migraine, Muscle Spasms, Nasal Congestion, Osteoarthritis (OA), Pain, Post-traumatic pain, Postoperative pain, Primary Dysmenorrhoea, Rheumatoid Arthritis, Rheumatoid Arthritis, Juvenile, Seasonal Allergic Rhinitis, Sinusitis, Tendinitis, Toothache

How Duofix works

Esomeprazole exerts its stomach acid-suppressing effects by preventing the final step in gastric acid production by covalently binding to sulfhydryl groups of cysteines found on the (H+, K+)-ATPase enzyme at the secretory surface of gastric parietal cells. This effect leads to inhibition of both basal and stimulated gastric acid secretion, irrespective of the stimulus. As the binding of esomeprazole to the (H+, K+)-ATPase enzyme is irreversible and new enzyme needs to be expressed in order to resume acid secretion, esomeprazole's duration of antisecretory effect that persists longer than 24 hours.

As with other non-selective NSAIDs, naproxen exerts it's clinical effects by blocking COX-1 and COX-2 enzymes leading to decreased prostaglandin synthesis. Although both enzymes contribute to prostaglandin production, they have unique functional differences. The COX-1 enzymes is constitutively active and can be found in normal tissues such as the stomach lining, while the COX-2 enzyme is inducible and produces prostaglandins that mediate pain, fever and inflammation. The COX-2 enzyme mediates the desired antipyretic, analgesic and anti-inflammatory properties offered by Naproxen, while undesired adverse effects such as gastrointestinal upset and renal toxicities are linked to the COX-1 enzyme.

Dosage

Duofix dosage

Rheumatoid Arthritis, Osteoarthritis and AnkylosingSpondylitis: The dosage is one tablet twice daily of 375 mg naproxen and 20 mg of esomeprazole or 500 mg naproxen and 20 mg of esomeprazole. The tablets are to be swallowed whole with liquid. Do not split, chew, crush or dissolve the tablet. This is to be taken at least 30 minutes before meals.

Directions for reconstitution of solution: Solution for injection is prepared by adding 5 ml of 0.9% Sodium Chloride for intravenous injection into the vial containing the dry powder. The reconstituted solution for injection is clear and colorless to very slightly yellow.

Preparations for Use and Administration of Esomeprazole 40 IV Injection: A solution for intravenous infusion is prepared by first reconstituting the contents of one vial with 5 ml of 0.9% Sodium Chloride and further diluting the resulting solution to a final volume of 50 ml. The resultant concentration after diluting to a final volume of 50 ml is 0.8 mg/ml.

• 20 mg dose: Withdraw 25 ml of the final solution and administer as an intravenous infusion over 10 minutes to 30 minutes.
• 10 mg dose: Withdraw 12.5 ml of the final solution and administer as an intravenous infusion over 10 minutes to 30 minutes.

Side Effects

The adverse effects reported with this combination may include gastrointestinal disorders like dyspepsia, diarrhea, nausea, flatulence, abdominal pain etc.

Toxicity

Blurred vision, confusion, drowsiness, dry mouth, flushing headache, nausea, rapid heartbeat, sweating

Although the over-the-counter (OTC) availability of naproxen provides convenience to patients, it also increases the likelihood of overdose. Thankfully, the extent of overdose is typically mild with adverse effects normally limited to drowsiness, lethargy, epigastric pain, nausea and vomiting. Although there is no antidote for naproxen overdose, symptoms will typically subside with appropriate supportive care.

Naproxen is classified as Category B during the first 2 trimesters of pregnancy, and as Category D during the third trimester. Naproxen is contraindicated in the 3rd trimester since it increases the risk of premature closure of the fetal ductus arteriosus and should be avoided in pregnant women starting at 30 weeks gestation.

Precaution

Patients with known CV disease/risk factors may be at greater risk. Progesic should be used with caution in patients with fluid retention or heart failure.

Interaction

Several studies conducted with naproxen and esomeprazole combination have shown no interaction between the two components.

Volume of Distribution

The apparent volume of distribution at steady state in healthy volunteers is approximately 16 L.

Naproxen has a volume of distribution of 0.16 L/kg.

Elimination Route

After oral administration, peak plasma levels (Cmax) occur at approximately 1.5 hours (Tmax). The Cmax increases proportionally when the dose is increased, and there is a three-fold increase in the area under the plasma concentration-time curve (AUC) from 20 to 40 mg. At repeated once-daily dosing with 40 mg, the systemic bioavailability is approximately 90% compared to 64% after a single dose of 40 mg. The mean exposure (AUC) to esomeprazole increases from 4.32 μmolhr/L on Day 1 to 11.2 μmolhr/L on Day 5 after 40 mg once daily dosing. The AUC after administration of a single 40 mg dose of Esomeprazole is decreased by 43% to 53% after food intake compared to fasting conditions. Esomeprazole should be taken at least one hour before meals.

Combination Therapy with Antimicrobials:

Esomeprazole magnesium 40 mg once daily was given in combination with Clarithromycin 500 mg twice daily and Amoxicillin 1000 mg twice daily for 7 days to 17 healthy male and female subjects. The mean steady state AUC and Cmax of esomeprazole increased by 70% and 18%, respectively during triple combination therapy compared to treatment with esomeprazole alone. The observed increase in esomeprazole exposure during co-administration with clarithromycin and amoxicillin is not expected to produce significant safety concerns.

Naproxen is available as a free acid and sodium salt. At comparable doses, (naproxen 500 mg = naproxen sodium 550 mg) they differ slightly in their rates of absorption, but otherwise they are therapeutically and pharmacologically equivalent. Naproxen sodium achieves a peak plasma concentration after 1 hour, while peak plasma concentration is observed after 2 hours with naproxen (free acid). There are no differences between the 2 forms in the post-absorption phase pharmacokinetics. The difference in initial absorption should be considered when treating acute pain, since naproxen sodium may offer a quicker onset of action.

The mean Cmax for the various formulations (immediate release, enteric coated, controlled release etc.) of naproxen are comparable and range from 94 mcg/mL to 97.4 mcg/mL. In one pharmacokinetic study, the mean Tmax of naproxen 500 mg (immediate release) given every 12 hours over 5 days was 3 hours, compared to a mean Tmax of 5 hours for Naprelan 1000 mg (controlled release) given every 24 hours over 5 days. In this same study, the AUC_0-24hr was 1446mcgxhr/mL for naproxen immediate release and 1448 mcgxhr/mL for the controlled release formulation. A separate study comparing the pharmacokinetics of Naprosyn tablets and EC-Naprosyn observed the following values: Tmax and AUC_0-12hrs of EC-Naprosyn were 4 hours and 845 mcgxhr/mL respectively, and Tmax and AUC_0-12hrs values of Naprosyn were 1.9 hours and 767 mcgxhr/mL respectively.

When given in combination with sumatriptan the Cmax of naproxen is roughly 36% lower compared to naproxen sodium 550 mg tablets, and the median Tmax is 5 hours.

Based on the AUC and Cmax of naproxen, Vimovo (naproxen/esomeprazole combination product) and enteric-coated naproxen may be considered bioequivalent.

Overall, naproxen is rapidly and completely absorbed when administered orally and rectally. Food may contribute to a delay in the absorption of orally administered naproxen, but will not affect the extent of absorption.

Half Life

1-1.5 hours

The elimination half-life of naproxen is reported to be 12-17 hours.

Clearance

Naproxen is cleared at a rate of 0.13 mL/min/kg.

Elimination Route

The plasma elimination half-life of esomeprazole is approximately 1 to 1.5 hours. Less than 1% of parent drug is excreted in the urine. Approximately 80% of an oral dose of esomeprazole is excreted as inactive metabolites in the urine, and the remainder is found as inactive metabolites in the feces.

After oral administration, about 95% of naproxen and it's metabolites can be recovered in the urine with 66-92% recovered as conjugated metabolite and less than 1% recovered as naproxen or desmethylnaproxen. Less than 5% of naproxen is excreted in the feces.

Pregnancy & Breastfeeding use

Naproxen & Esomeprazole both are pregnancy category B drug. This combination should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Naproxen & Esomeprazole are likely to be excreted in human milk, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Contraindication

Contraindicated in known hypersensitivity to any component of Progesic or substituted benzimidazoles, history of asthma, urticaria or other allergic-type reactions after taking aspirin or other NSAIDs, use during the peri-operative period in the setting of coronary artery bypass graft (CABG) surgery, late pregnancy

Special Warning

Geriatric Patients: Studies indicate that although total plasma concentration of naproxen is unchanged, the unbound plasma fraction of naproxen is increased in the elderly. Use caution when high doses are required and some adjustment of dosage may be required in elderly patients.

Pediatric Patients: The safety and efficacy of naproxen & esomeprazole in children younger than 18 years have not been established. This is therefore not recommended for use in children.

Patients With Moderate to Severe Renal Impairment: Naproxen-containing products are not recommended for use in patients with moderate to severe or severe renal impairment (creatinine clearance < 30 mL/min).

Hepatic Insufficiency: Monitor patients with mild to moderate hepatic impairment closely and consider a possible dose reduction based on the naproxen. This combination is not recommended in patients with severe hepatic impairment because esomeprazole doses should not exceed 20 mg daily in these patients.

Acute Overdose

Overdose of Naproxen: Significant naproxen overdosage may be characterized by lethargy, drowsiness, epigastric pain, abdominal discomfort, heartburn, indigestion, nausea, transient alterations in liver function, hypoprothrombinemia, renal dysfunction, metabolic acidosis, apnea, vomiting etc.

Overdose of Esomeprazole: The major signs of acute toxicity were reduced motor activity, changes in respiratory frequency, tremor and intermittent clonic convulsions etc.

Storage Condition

Store between 15-30°C. Protect from light.

Tablet: Protect from light and store below 30° C temperature in a dry place.

Suppository: Store below 25°C temperature.

Gel: Store in a cool and dry place protected from light.

Innovators Monograph

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