Esomeprazole

Esomeprazole is a Proton Pump Inhibitor of drug belonging to Gastrointestinal Agent.

Esomeprazole is a proton pump inhibitor used to treat GERD, reduce the risk of NSAID associated gastric ulcers, eradicate H. pylori, and to treat conditions causing gastric acid hypersecretion.

Esomeprazole rapidly absorbed (oral). The bioavailability of Esomeprazole is 64% (single 40 mg dose); approximately 90% (repeated 40 mg dose). The Time to peak plasma concentrations approximately 1-2 hours. The apparent volume of distribution at steady state in healthy volunteers is approximately 16 L. Esomeprazole is 97% bound to plasma proteins. Esomeprazole extensively metabolized in the liver primarily by CYP2C19 isoenzyme to form inactive hydroxy and desmethyl metabolites, and to a lesser extent by CYP3A4 isoenzyme to sulfone metabolite (main metabolite in plasma).

Esomeprazole shows side effects like Headache, nausea, diarrhea, gas, constipation, dry mouth, drowsiness.

Esomeprazole is available in the form of Oral capsule, Intravenous powder for Injection, Oral Tablet.

Esomeprazole is available in India, US, Spain, Australia, Singapore, Canada, Spain, Japan, China, and Italy.

Esomeprazole belongs to the Gastrointestinal Agent acts as a Proton Pump Inhibitor.

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.

The onset of action take place within 1 hour after taking Esomeprazole in oral forms, while it will start to work immediately after intravenous injection.

Esomeprazole may remain in your body for an average duration of 9 hours.

Esomeprazole is available in the form of Oral capsule, Intravenous powder for injection, Oral Tablet.

Esomeprazole Capsule and Tablet is taken orally, while powder for injection is given intravenous route.

Esomeprazole is an anti-ulcer medicine. It is used to treat stomach and intestinal conditions like peptic ulcers (sores in the lining of your stomach and intestine), esophagitis (swelling of your food pipe), and gastroesophageal reflux disease (a condition in which the stomach acid flows back into your food pipe), etc. It also relieves stress ulcers (sores in the stomach and intestine that may occur due to illness, infections, etc.) and acidity caused due to the intake of painkillers. It works by stopping the excess production of acid in your stomach.

Esomeprazole is a Proton Pump Inhibitor of drug belonging to Gastrointestinal Agent.

Esomeprazole is proton pump inhibitor suppresses gastric acid secretion by inhibition of the H⁺/K⁺-ATPase in the gastric parietal cell. Esomeprazole is the S-isomer of omeprazole.

Esomeprazole is approved for use in the following clinical indications

Adult Indication

• Eosinophilic esophagitis
• Gastroesophageal reflux disease, erosive or nonerosive
• Helicobacter pylori eradication
• Pathological hypersecretory conditions
• Peptic ulcer disease, treatment of complicated ulcers
• Prevention of NSAID-induced gastric ulcers
• Treatment of NSAID-induced gastric ulcers
• Upper GI bleed, acute

Pediatric Indication

• Erosive esophagitis associated with GERD
• GERD, symptomatic
• Helicobacter pylori eradication

Adult Dose

• Eosinophilic esophagitis

Oral: 20 to 40 mg twice daily for an 8-week trial.

• Gastroesophageal reflux disease, erosive or nonerosive

Oral: 20 to 40 mg once daily for 4 to 8 weeks.

IV (alternative route): 20 or 40 mg once daily for ≤10 days.

• Pathological hypersecretory conditions

Oral: Esomeprazole magnesium, esomeprazole strontium: 40 mg twice daily; adjust regimen to individual patient needs; doses up to 240 mg daily have been administered.

• Peptic ulcer disease, treatment of complicated ulcers

Oral, IV: 40 mg twice daily for 4 weeks, followed by 40 mg once daily.

• Prevention of NSAID-induced gastric ulcers

Oral: Esomeprazole magnesium, esomeprazole strontium: 20 to 40 mg once daily for up to 6 months.

• Treatment of NSAID-induced gastric ulcers

Oral: Esomeprazole magnesium: 20 mg once daily for 8 weeks.

Pediatric Dose

• Erosive esophagitis associated with GERD

Oral: Infants:

3 to 5 kg: 2.5 mg once daily for up to 6 weeks.

>5 to 7.5 kg: 5 mg once daily for up to 6 weeks.

>7.5 kg: 10 mg once daily for up to 6 weeks.

Children 1 to 11 years:

<20 kg: 10 mg once daily for 8 weeks.

≥20 kg: 10 or 20 mg once daily for 8 weeks.

Children ≥12 years and Adolescents

Oral: 20 to 40 mg once daily for 4 to 8 weeks.

IV: Infants:

0.5 mg/kg/dose once daily.

Children and Adolescents ≤17 years:

<55 kg: 10 mg once daily.

≥55 kg: 20 mg once daily.

• GERD, symptomatic

Children and Adolescents: Oral:

<20 kg: 10 mg once daily.

≥20 kg: 20 mg once daily.

• Helicobacter pylori eradication

15 to <25 kg: 20 mg twice daily.

25 to 34 kg: 30 mg twice daily.

>34 kg: 40 mg twice daily.

Esomeprazole is available in various strengths as 20 mg; 40 mg; 10 mg; 2.5 mg; 5 mg; 24.65 mg; 49.3 mg.

Esomeprazole is available in the form of Oral capsule, Intravenous powder for injection, Oral Tablet.

• Dosage Adjustment in Kidney Patient

Oral:

eGFR ≥30 mL/minute/1.73 m²: No dosage adjustment necessary.

eGFR <30 mL/minute/1.73 m²: Use is not recommended.

IV: No dosage adjustment necessary.

• Dosage Adjustment in Hepatic impairment Patient

Oral:

Mild to moderate impairment (Child-Pugh class A or B): No dosage adjustment necessary.

Severe impairment (Child-Pugh class C):

Erosive esophagitis, H. pylori eradication or prevention of nonsteroidal anti-inflammatory drug–induced gastric ulcers: Maximum dose of 20 mg once daily.

Pathological hypersecretory conditions (Zollinger-Ellison syndrome): Initial: 20 mg twice daily.

IV:

Treatment of GERD (short-term):

Mild to moderate impairment (Child-Pugh class A or B): No dosage adjustment necessary.

Severe impairment (Child-Pugh class C): Dose should not exceed 20 mg daily.

Esomeprazole is contraindicated in patients with

• Esomeprazole I.V. is contraindicated in patients with known hypersensitivity to substituted benzimidazoles or to any component of the formulation. Hypersensitivity reactions may include anaphylaxis, anaphylactic shock, angioedema, bronchospasm, acute tubulointerstitial nephritis, and urticaria.
• Proton pump inhibitors (PPIs), including Esomeprazole I.V., are contraindicated in patients receiving rilpivirine containing products.

• Presence Of Gastric Malignancy

In adults, symptomatic response to therapy with Esomeprazole I.V. does not preclude the presence of gastric malignancy. Consider additional follow-up and diagnostic testing in adults patients who have suboptimal response or an early symptomatic relapse after completing treatment with a PPI. In older patients also consider an endoscopy.

• Acute Tubulointerstitial Nephritis

Acute tubulointerstitial nephritis (TIN) has been observed in patients taking PPIs and may occur at any point during PPI therapy. Patients may present with varying signs and symptoms from symptomatic hypersensitivity reactions to nonspecific symptoms of decreased renal function (e.g., malaise, nausea, anorexia). In reported case series, some patients were diagnosed on biopsy and in the absence of extra-renal manifestations (e.g., fever, rash or arthralgia). Discontinue Esomeprazole I.V. and evaluate patients with suspected acute TIN.

• Clostridium Difficile-Associated Diarrhea

Published observational studies suggest that PPI therapy like Esomeprazole I.V. may be associated with an increased risk of Clostridium difficile-associated diarrhea, especially in hospitalized patients. This diagnosis should be considered for diarrhea that does not improve. Patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated.

• Bone Fracture

Several published observational studies suggest that proton pump inhibitor (PPI) therapy may be associated with an increased risk for osteoporosis-related fractures of the hip, wrist, or spine. The risk of fracture was increased in patients who received high-dose, defined as multiple daily doses, and long-term PPI therapy (a year or longer). Patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated. Patients at risk for osteoporosis-related fractures should be managed according to established treatment guidelines.

• Severe Cutaneous Adverse Reactions
• Severe cutaneous adverse reactions, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) have been reported in association with the use of PPIs. Discontinue Esomeprazole I.V. at the first signs or symptoms of severe cutaneous adverse reactions or other signs of hypersensitivity and consider further evaluation.
• Cutaneous And Systemic Lupus Erythematosus
• Cutaneous lupus erythematosus (CLE) and systemic lupus erythematosus (SLE) have been reported in patients taking PPIs, including esomeprazole. These events have occurred as both new onset and an exacerbation of existing autoimmune disease. The majority of PPI-induced lupus erythematosus cases were CLE. The most common form of CLE reported in patients treated with PPIs was subacute CLE (SCLE) and occurred within weeks to years after continuous drug therapy in patients ranging from infants to the elderly. Generally, histological findings were observed without organ involvement. Systemic lupus erythematosus (SLE) is less commonly reported than CLE in patients receiving PPIs. PPI associated SLE is usually milder than non-drug induced SLE. Onset of SLE typically occurred within days to years after initiating treatment primarily in patients ranging from young adults to the elderly. The majority of patients presented with rash; however, arthralgia and cytopenia were also reported. Avoid administration of PPIs for longer than medically indicated. If signs or symptoms consistent with CLE or SLE are noted in patients receiving Esomeprazole I.V., discontinue the drug and refer the patient to the appropriate specialist for evaluation. Most patients improve with discontinuation of the PPI alone in 4 to 12 weeks. Serological testing (e.g., ANA) may be positive and elevated serological test results may take longer to resolve than clinical manifestations.
• Interaction With Clopidogrel
• Avoid concomitant use of Esomeprazole I.V. with clopidogrel. Clopidogrel is a prodrug. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. The metabolism of clopidogrel to its active metabolite can be impaired by use with concomitant medications, such as esomeprazole, that inhibit CYP2C19 activity. Concomitant use of clopidogrel with 40 mg esomeprazole reduces the pharmacological activity of clopidogrel. When using Esomeprazole I.V. consider alternative anti-platelet therapy.
• Hypomagnesemia And Mineral Metabolism

Hypomagnesemia, symptomatic and asymptomatic, has been reported rarely in patients treated with PPIs for at least three months, in most cases after a year of therapy. Serious adverse events include tetany, arrhythmias, and seizures. Hypomagnesemia may lead to hypocalcemia and/or hypokalemia and may exacerbate underlying hypocalcemia in at-risk patients. In most patients, treatment of hypomagnesemia required magnesium replacement and discontinuation of the PPI. For patients expected to be on prolonged treatment or who take PPIs with medications such as digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), health care professionals may consider monitoring magnesium levels prior to initiation of PPI treatment and periodically. Consider monitoring magnesium and calcium levels prior to initiation of Esomeprazole I.V. and periodically while on treatment in patients with a preexisting risk of hypocalcemia (e.g., hypoparathyroidism). Supplement with magnesium and/or calcium, as necessary. If hypocalcemia is refractory to treatment, consider discontinuing the PPI.

• Interaction With St. John’s Wort or Rifampin

Drugs which induce CYP2C19 or CYP3A4 can substantially decrease esomeprazole concentrations. Avoid concomitant use of Esomeprazole I.V. with St. John’s Wort or rifampin.

• Interactions With Diagnostic Investigations for Neuroendocrine Tumors

Serum chromogranin A (CgA) levels increase secondary to drug-induced decreases in gastric acidity. The increased CgA level may cause false positive results in diagnostic investigations for neuroendocrine tumors. Healthcare providers should temporarily stop esomeprazole treatment at least 14 days before assessing CgA levels and consider repeating the test if initial CgA levels are high. If serial tests are performed (e.g., for monitoring), the same commercial laboratory should be used for testing, as reference ranges between tests may vary.

• Interaction With Methotrexate

Literature suggests that concomitant use of PPIs with methotrexate (primarily at high dose; see methotrexate prescribing information) may elevate and prolong serum levels of methotrexate and/or its metabolite, possibly leading to methotrexate toxicities. In high-dose methotrexate administration, a temporary withdrawal of the PPI may be considered in some patients.

• Fundic Gland Polyps

PPI use is associated with an increased risk of fundic gland polyps that increases with long-term use, especially beyond one year. Most PPI users who developed fundic gland polyps were asymptomatic and fundic gland polyps were identified incidentally on endoscopy. Use the shortest duration of PPI therapy appropriate to the condition being treated.

Esomeprazole is likely present in human milk. Esomeprazole is the S-isomer of omeprazole and limited data indicate that maternal doses of omeprazole 20 mg daily produce low levels in human milk. Caution should be exercised when Esomeprazole is administered to a nursing woman.

There are no adequate and well-controlled studies with Esomeprazole in pregnant women. Esomeprazole is the S-isomer of omeprazole. Available epidemiologic data fail to demonstrate an increased risk of major congenital malformations or other adverse pregnancy outcomes with first trimester omeprazole use.

• Common

Headache, nausea, diarrhea, gas, constipation, dry mouth, drowsiness.

• Rare

Blistering, peeling, or bleeding skin; sores on the lips, nose, mouth, or genitals; swollen glands; shortness of breath; fever; or flu-like symptoms, Rash hives; itching; swelling of the eyes, face, lips, mouth, throat, or tongue, difficulty breathing or swallowing; or hoarseness, irregular, fast, or pounding heartbeat muscle spasms; uncontrollable shaking of a part of the body, excessive tiredness, lightheadedness, dizziness, or seizures, severe diarrhea with watery stools, stomach pain, or fever that does not go away, new or worsening joint pain; rash on cheeks or arms that is sensitive to sunlight, increased or decreased urination, blood in urine, fatigue, nausea, loss of appetite, fever, rash, or joint pain.

• Interference with Antiretroviral Therapy

Concomitant use of atazanavir and nelfinavir with proton pump inhibitors is not recommended. Co-administration of atazanavir with proton pump inhibitors is expected to substantially decrease atazanavir plasma concentrations and may result in a loss of therapeutic effect and the development of drug resistance. Co-administration of saquinavir with proton pump inhibitors is expected to increase saquinavir concentrations, which may increase toxicity and require dose reduction. Omeprazole, of which esomeprazole is an enantiomer, has been reported to interact with some antiretroviral drugs. The clinical importance and the mechanisms behind these interactions are not always known. Increased gastric pH during omeprazole treatment may change the absorption of the antiretroviral drug. Other possible interaction mechanisms are via CYP2C19. Reduced concentrations of atazanavir and nelfinavir for some antiretroviral drugs, such as atazanavir and nelfinavir, decreased serum levels have been reported when given together with omeprazole. Following multiple doses of nelfinavir (1250 mg, twice daily) and omeprazole (40 mg daily), AUC was decreased by 36% and 92%, Cmax by 37% and 89% and C min by 39% and 75% respectively for nelfinavir and M8. Following multiple doses of atazanavir (400 mg, daily) and omeprazole (40 mg, daily, 2 hr before atazanavir), AUC was decreased by 94%, Cmax by 96%, and Cmin by 95%. Concomitant administration with omeprazole and drugs such as atazanavir and nelfinavir is therefore not recommended. Increased concentrations of saquinavir for other antiretroviral drugs, such as saquinavir, elevated serum levels have been reported, with an increase in AUC by 82%, in C max by 75%, and in C min by 106%, following multiple dosing of saquinavir/ritonavir (1000/100 mg) twice daily for 15 days with omeprazole 40 mg daily co-administered days 11 to 15. Therefore, clinical and laboratory monitoring for saquinavir toxicity is recommended during concurrent use with Esomeprazole. Dose reduction of saquinavir should be considered from the safety perspective for individual patients. There are also some antiretroviral drugs of which unchanged serum levels have been reported when given with omeprazole.

• Drugs for Which Gastric pH Can Affect Bioavailability

Due to its effects on gastric acid secretion, esomeprazole can reduce the absorption of drugs where gastric pH is an important determinant of their bioavailability. Like with other drugs that decrease the intragastric acidity, the absorption of drugs such as ketoconazole, atazanavir, iron salts, erlotinib, and mycophenolate mofetil (MMF) can decrease, while the absorption of drugs such as digoxin can increase during treatment with esomeprazole. Esomeprazole is an enantiomer of omeprazole. Concomitant treatment with omeprazole (20 mg daily) and digoxin in healthy subjects increased the bioavailability of digoxin by 10% (30% in two subjects). Co-administration of digoxin with Esomeprazole is expected to increase the systemic exposure of digoxin. Therefore, patients may need to be monitored when digoxin is taken concomitantly with Esomeprazole. Co-administration of omeprazole in healthy subjects and in transplant patients receiving MMF has been reported to reduce the exposure to the active metabolite, mycophenolic acid (MPA), possibly due to a decrease in MMF solubility at an increased gastric pH. The clinical relevance of reduced MPA exposure on organ rejection has not been established in transplant patients receiving Esomeprazole and MMF. Use Esomeprazole with caution in transplant patients receiving MMF.

• Effects on Hepatic Metabolism/Cytochrome P-450 Pathways

Esomeprazole is extensively metabolized in the liver by CYP2C19 and CYP3A4. In vitro and in vivo studies have shown that esomeprazole is not likely to inhibit CYPs 1A2, 2A6, 2C9, 2D6, 2E1, and 3A4. No clinically relevant interactions with drugs metabolized by these CYP enzymes would be expected. Drug interaction studies have shown that esomeprazole does not have any clinically significant interactions with phenytoin, warfarin, quinidine, clarithromycin, or amoxicillin. However, post-marketing reports of changes in prothrombin measures have been received among patients on concomitant warfarin and esomeprazole therapy. Increases in INR and prothrombin time may lead to abnormal bleeding and even death. Patients treated with proton pump inhibitors and warfarin concomitantly may need to be monitored for increases in INR and prothrombin time. Esomeprazole may potentially interfere with CYP2C19, the major esomeprazole metabolizing enzyme. Co-administration of esomeprazole 30 mg and diazepam, a CYP2C19 substrate, resulted in a 45% decrease in clearance of diazepam. Clopidogrel Clopidogrel is metabolized to its active metabolite in part by CYP2C19. Concomitant use of esomeprazole 40 mg results in reduced plasma concentrations of the active metabolite of clopidogrel and a reduction in platelet inhibition. Avoid concomitant administration of Esomeprazole with clopidogrel. When using Esomeprazole, consider use of alternative anti-platelet therapy. Omeprazole acts as an inhibitor of CYP2C19. Omeprazole, given in doses of 40 mg daily for one week to 20 healthy subjects in cross-over study, increased C max and AUC of cilostazol by 10 Reference ID: 3675799 8 18% and 26% respectively. Cmax and AUC of one of its active metabolites, 3,4-dihydrocilostazol, which has 4-7 times the activity of cilostazol, were increased by 29% and 69% respectively. Co-administration of cilostazol with esomeprazole is expected to increase concentrations of cilostazol and its above-mentioned active metabolite. Therefore, a dose reduction of cilostazol from 100 mg twice daily to 50 mg twice daily should be considered. Concomitant administration of esomeprazole and a combined inhibitor of CYP2C19 and CYP3A4, such as voriconazole, may result in more than doubling of the esomeprazole exposure. Dose adjustment of esomeprazole is not normally required. However, in patients with Zollinger-Ellison’s Syndrome, who may require higher doses up to 240 mg/day, dose adjustment may be considered. Drugs known to induce CYP2C19 or CYP3A4 or both (such as rifampin) may lead to decreased esomeprazole serum levels. Omeprazole, of which esomeprazole is an enantiomer, has been reported to interact with St. John’s Wort an inducer of CYP3A4. In a cross-over study in 12 healthy male subjects, St. John’s Wort (300 mg three times daily for 14 days) significantly decreased the systemic exposure of omeprazole in CYP2C19 poor metabolizers (Cmax and AUC decreased by 37.5% and 37.9%, respectively) and extensive metabolizers (Cmax and AUC decreased by 49.6 % and 43.9%, respectively). Avoid concomitant use of St. John’s Wort or rifampin with Esomeprazole.

• Interactions With Investigations of Neuroendocrine Tumors

Drug-induced decrease in gastric acidity results in enterochromaffin-like cell hyperplasia and increased Chromogranin A levels which may interfere with investigations for neuroendocrine tumors.

• Tacrolimus

Concomitant administration of esomeprazole and tacrolimus may increase the serum levels of tacrolimus.

• Combination Therapy with Clarithromycin

Co-administration of esomeprazole, clarithromycin, and amoxicillin has resulted in increases in the plasma levels of esomeprazole and 14-hydroxyclarithromycin. Concomitant administration of clarithromycin with other drugs can lead to serious adverse reactions due to drug interactions. Because of these drug interactions, clarithromycin is contraindicated for co-administration with certain drugs.

• Methotrexate

Case reports, published population pharmacokinetic studies, and retrospective analyses suggest that concomitant administration of PPIs and methotrexate (primarily at high dose; see methotrexate prescribing information) may elevate and prolong serum levels of methotrexate and/or its metabolite hydroxymethotrexate. However, no formal drug interaction studies of methotrexate with PPIs have been conducted.

The common side effects of Esomeprazole include the following

• Common side effects

Headache, nausea, diarrhea, gas, constipation, dry mouth, drowsiness.

• Rare side effects

Blistering, peeling, or bleeding skin; sores on the lips, nose, mouth, or genitals; swollen glands; shortness of breath; fever; or flu-like symptoms, Rash hives; itching; swelling of the eyes, face, lips, mouth, throat, or tongue, difficulty breathing or swallowing; or hoarseness, irregular, fast, or pounding heartbeat muscle spasms; uncontrollable shaking of a part of the body, excessive tiredness, lightheadedness, dizziness, or seizures, severe diarrhea with watery stools, stomach pain, or fever that does not go away, new or worsening joint pain; rash on cheeks or arms that is sensitive to sunlight, increased or decreased urination, blood in urine, fatigue, nausea, loss of appetite, fever, rash, or joint pain.

• Pregnancy

Pregnancy Category C

There are no adequate and well-controlled studies with Esomeprazole in pregnant women. Esomeprazole is the S-isomer of omeprazole. Available epidemiologic data fail to demonstrate an increased risk of major congenital malformations or other adverse pregnancy outcomes with first trimester omeprazole use.

• Nursing Mothers

Esomeprazole is likely present in human milk. Esomeprazole is the S-isomer of omeprazole and limited data indicate that maternal doses of omeprazole 20 mg daily produce low levels in human milk. Caution should be exercised when Esomeprazole is administered to a nursing woman.

• Pediatric Use

The safety and effectiveness of Esomeprazole have been established in pediatric patients 1 to 17 years of age for short-term treatment (up to eight weeks) of GERD. The safety and effectiveness of Esomeprazole have been established in pediatric patients 1 month to less than 1 year for short-term treatment (up to 6 weeks) of erosive esophagitis due to acid-mediated GERD. However, the safety and effectiveness of Esomeprazole have not been established in patients less than 1 month of age.

• Geriatric Use

Of the total number of patients who received Esomeprazole in clinical trials, 1459 were 65 to 74 years of age and 354 patients were ≥ 75 years of age. No overall differences in safety and efficacy were observed between the elderly and younger individuals, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Symptoms: Weakness, confusion, headache, drowsiness, blurred vision, tachycardia, diaphoresis, flushing, dry mouth, nausea and other gastrointestinal symptoms.

Management: Symptomatic and supportive treatment.

Pharmacodynamic

Esomeprazole is a compound that inhibits gastric acid secretion and is indicated in the treatment of gastroesophageal reflux disease (GERD), the healing of erosive esophagitis, and H. pylori eradication to reduce the risk of duodenal ulcer recurrence. Esomeprazole belongs to a new class of antisecretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or H2 histamine antagonistic properties, but that suppress gastric acid secretion by specific inhibition of the H⁺/K⁺ ATPase at the secretory surface of the gastric parietal cell. By doing so, it inhibits acid secretion into the gsatric lumen. This effect is dose-related and leads to inhibition of both basal and stimulated acid secretion irrespective of the stimulus.

Pharmacokinetics

• Absorption

Esomeprazole rapidly absorbed (oral). The bioavailability of Esomeprazole is 64% (single 40 mg dose); approximately 90% (repeated 40 mg dose). The Time to peak plasma concentrations approximately 1-2 hours.

• Distribution

The apparent volume of distribution at steady state in healthy volunteers is approximately 16 L. Esomeprazole is 97% bound to plasma proteins.

• Metabolism and Excretion

Esomeprazole extensively metabolized in the liver primarily by CYP2C19 isoenzyme to form inactive hydroxy and desmethyl metabolites, and to a lesser extent by CYP3A4 isoenzyme to sulfone metabolite (main metabolite in plasma).

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