OMIS 20 20MG CAPSULE

Indications

• Gastric ulcer
• Duodenal ulcer
• Gastro-oesophageal reflux disease (GERD)
• Severe oesophagitis
• Helicobacter pylori eradication (in combination therapy)
• Prevention of NSAID-associated gastric and duodenal ulcers
• Zollinger-Ellison syndrome

Dosage

Adults: The usual dose for adults is 20 mg once daily for 4 weeks for duodenal ulcer and GERD. For gastric ulcer, the dose may be 20 mg to 40 mg once daily

Mechanism of action

Omeprazole works by specifically binding to the proton pump (H+/K+ ATPase) in the gastric parietal cells, leading to irreversible inhibition of acid secretion. This binding prevents the exchange of hydrogen ions for potassium ions, effectively reducing the production of gastric acid and promoting healing of acid-related conditions.

Pharmacodynamics

The pharmacodynamic effects of omeprazole manifest as a significant decrease in gastric acidity, which improves symptoms related to excessive acid secretion. The onset of action typically occurs within an hour of administration, with maximum effect seen within 2 to 4 days of continuous use. The duration of action allows for once-daily dosing in most indications.

Pharmacokinetics

Omeprazole is rapidly absorbed from the gastrointestinal tract, reaching peak plasma concentrations within 0.5 to 3.5 hours after oral administration. It is extensively metabolized in the liver via the cytochrome P450 system, primarily CYP2C19 and CYP3A4, leading to the formation of inactive metabolites. The elimination half-life is approximately 0.5 to 1 hour, but the effects on gastric acid secretion last much longer due to the irreversible nature of proton pump inhibition. Omeprazole is excreted mainly in the urine as metabolites, with less than 1% of the drug excreted unchanged.

Contra-indications

• Hypersensitivity to omeprazole or any component of the formulation
• Use with caution in patients with severe liver impairment

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Headache
• Abdominal pain
• Flatulence
• Constipation
• Dizziness
• Fatigue
• Rash
• Muscle weakness
• Gastrointestinal candidiasis
• Aggression
• Agitation
• Bronchospasm
• Encephalopathy

Interactions

• Cenobamate may increase exposure to omeprazole
• Fedratinib may increase exposure to omeprazole
• Apalutamide may decrease exposure to omeprazole
• Cilostazol may increase exposure to omeprazole

Precautions

• Monitor patients for gastrointestinal symptoms
• Use caution in patients with a history of liver disease
• Consider potential for vitamin B12 deficiency with long-term use
• Monitor for signs of Clostridium difficile infection in the colon

Pregnancy

Not known to be harmful during pregnancy, but should be used only if clearly needed.

Breast-feeding

Excreted in breast milk, caution is advised when administered to nursing mothers.

Storage

Store below 25 degrees Celsius. Protect from moisture. Keep out of reach of children.

Formulations

• Orodispersible tablets
• Gastro-resistant capsules
• Intravenous injection
• Oral suspension

Indications

• Gastroesophageal reflux disease (GERD)
• Peptic ulcers
• Zollinger-Ellison syndrome
• Dyspepsia

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing information.

Adults: Refer to the BNF for specific dosing information and adjustments based on clinical indications.

Mechanism of action

Gastro works by selectively inhibiting the action of histamine at the H2 receptor sites in the gastric parietal cells. This inhibition reduces gastric acid secretion in response to food intake and other stimuli, leading to a decrease in both basal and stimulated acid secretion.

Pharmacodynamics

The pharmacodynamic effects of Gastro are primarily related to its ability to decrease gastric acidity. By inhibiting histamine action at the H2 receptors, it reduces the volume and concentration of gastric acid. This results in an increased pH level in the gastric lumen, which helps to promote healing of ulcerated tissue and alleviate symptoms such as heartburn and acid indigestion.

Pharmacokinetics

Gastro is well absorbed from the gastrointestinal tract, with peak plasma concentrations occurring within 1 to 3 hours after oral administration. It has a bioavailability of approximately 40% due to first-pass metabolism. The drug is primarily excreted in the urine, with a half-life of about 2 to 3 hours. Adjustments in dosing may be necessary in patients with renal impairment due to altered clearance.

Adverse effects

• Headache
• Dizziness
• Constipation
• Diarrhea
• Nausea
• Vomiting
• Fatigue

Precautions

• Use with caution in patients with renal impairment
• Monitor for potential allergic reactions
• Consider dosage adjustments in elderly patients

Pregnancy

Safety in pregnancy has not been established; use only if clearly needed.

Breast-feeding

Excreted in breast milk; caution is advised.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Formulations

• Tablets
• Oral suspension

Indications

• Bacterial infections
• Tuberculosis
• HIV-associated infections
• Urinary tract infections
• Respiratory infections

Dosage

Children: Refer to pediatric dosing guidelines based on specific antibiotic and condition.

Adults: Refer to specific antibiotic guidelines and local resistance patterns for appropriate dosing.

Mechanism of action

The mechanism of action varies depending on the type of antibiotic. Generally, antibiotics target specific bacterial processes, such as cell wall synthesis, protein synthesis, or nucleic acid metabolism. In cases of resistance, bacteria may employ efflux pumps to expel the drug, modify the drug's target site, or produce enzymes that inactivate the antibiotic.

Pharmacodynamics

Pharmacodynamics involves the relationship between the drug concentration and its effect on bacteria. The effectiveness of an antibiotic can be influenced by its minimum inhibitory concentration (MIC) and the time or concentration that remains above this threshold. In resistant strains, higher concentrations or prolonged exposure may be required to achieve a therapeutic effect, which can lead to increased toxicity and adverse effects.

Pharmacokinetics

Pharmacokinetics refers to the absorption, distribution, metabolism, and excretion (ADME) of antibiotics. Resistance can affect the pharmacokinetic profile of a drug, as altered permeability or increased efflux may reduce drug concentration at the site of action. Understanding the pharmacokinetics of both the antibiotic and the resistant bacteria is crucial for effective treatment planning.

Pregnancy

Consult healthcare provider. The effects of resistant strains during pregnancy may vary based on the specific infection and required treatment.

Breast-feeding

Consult healthcare provider. The safety of treating resistant infections during breastfeeding depends on the specific medication used.

Storage

Store in a cool, dry place away from direct sunlight. Ensure the medication is kept out of reach of children.