LOCID 20

Indications

• Neuropathic pain
• Postherpetic neuralgia
• Osteoarthritis pain
• Rheumatoid arthritis
• Muscle pain

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines.

Adults: Refer to the specific product guidelines, as dosages can vary based on the formulation and strength.

Mechanism of action

Capsaicin induces the release of substance P, a neuropeptide involved in the transmission of pain signals. By stimulating the TRPV1 receptor, capsaicin causes an initial activation followed by a prolonged desensitization of the receptor, ultimately reducing the sensation of pain.

Pharmacodynamics

Capsaicin exhibits its analgesic effects through the modulation of pain pathways in the central nervous system. The depletion of substance P diminishes the perception of pain, which can be particularly beneficial in chronic pain conditions. Additionally, it may produce a warming sensation upon application, which can further contribute to its therapeutic effects.

Pharmacokinetics

Capsaicin is poorly absorbed through intact skin but is effective when applied topically. After application, it binds to the TRPV1 receptor in the epidermis and dermis, leading to localized effects. Systemic absorption is minimal, and the duration of action can last several hours to days, depending on the formulation and frequency of application.

Pregnancy

Consult the local guidelines for use during pregnancy.

Breast-feeding

Consult the local guidelines for use during breastfeeding.

Storage

Store in a cool, dry place, away from direct sunlight.

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