FENAMEX SPAS 250/10MG TABLET

Indications

• Irritable bowel syndrome
• Functional bowel disorders
• Gastrointestinal spasms

Dosage

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

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

Dicyclomine exerts its effects as a non-selective anticholinergic, blocking the action of acetylcholine at muscarinic receptors in the smooth muscle of the gastrointestinal tract. This inhibition leads to a decrease in gastrointestinal motility and secretion, alleviating spasms and cramping.

Pharmacodynamics

Dicyclomine's antispasmodic actions are primarily due to its ability to inhibit the parasympathetic nervous system's influence on the gastrointestinal tract. This results in reduced peristalsis and relaxation of the smooth muscle, which is beneficial in conditions characterized by excessive gastrointestinal motility and pain.

Pharmacokinetics

Dicyclomine is well absorbed after oral administration, with peak plasma concentrations occurring within 1 to 2 hours. The drug is extensively distributed throughout the body, and it is metabolized in the liver with a half-life of approximately 1 to 2 hours. The elimination is primarily via the urine, with some excretion as unchanged drug.

Contra-indications

• Hypersensitivity to dicyclomine or any component of the formulation
• Severe ulcerative colitis
• Glaucoma
• Myasthenia gravis
• Obstructive uropathy
• Tachycardia
• Severe hepatic or renal impairment

Adverse effects

• Dry mouth
• Dizziness
• Nausea
• Vomiting
• Constipation
• Blurred vision
• Urinary retention
• Increased heart rate
• Confusion
• Hallucinations

Interactions

• Anticholinergic agents may enhance the effects
• CNS depressants may have additive effects
• Potassium-containing medications may lead to increased risk of gastrointestinal side effects
• Antacids may affect the absorption

Precautions

• Use with caution in patients with a history of gastrointestinal obstruction
• Monitor for signs of urinary retention
• Use with caution in elderly patients due to increased sensitivity to anticholinergic effects
• Assess for potential drug interactions

Pregnancy

Dicyclomine is classified as Category C. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Dicyclomine is excreted in breast milk. Caution is advised when administering to nursing mothers.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• Oral tablets
• Oral syrup
• Injection

Indications

• Mild to moderate pain
• Dysmenorrhea
• Postoperative pain
• Osteoarthritis
• Rheumatoid arthritis

Dosage

Children: For

Adults: The usual adult dose is 500 mg initially, followed by 250 mg every 8 hours as needed. The maximum daily dose should not exceed 2000 mg.

Mechanism of action

Mefenamic acid exerts its therapeutic effect by inhibiting the cyclooxygenase (COX) enzymes, which are responsible for the conversion of arachidonic acid to prostaglandins. By reducing prostaglandin production, mefenamic acid decreases inflammation, pain, and fever. This inhibition primarily occurs through the non-selective blockade of COX-1 and COX-2 isoforms.

Pharmacodynamics

The pharmacodynamics of mefenamic acid involve its analgesic, anti-inflammatory, and antipyretic properties. The drug is effective in reducing pain and inflammation due to its ability to lower prostaglandin levels, which play a key role in the inflammatory response. Mefenamic acid tends to have a rapid onset of action, typically within 1 to 2 hours after administration, and its effects can last for several hours, providing relief from pain.

Pharmacokinetics

Mefenamic acid is well absorbed from the gastrointestinal tract, with peak plasma concentrations occurring approximately 2 to 4 hours after oral administration. The drug is extensively metabolized in the liver, primarily through glucuronidation, leading to the formation of active and inactive metabolites. It has a relatively long half-life of about 2 to 4 hours, and it is excreted mainly in the urine, both as unchanged drug and as metabolites. The pharmacokinetics can be influenced by factors such as age, liver function, and concurrent medications.

Contra-indications

• Hypersensitivity to mefenamic acid or any of its excipients
• Active or history of peptic ulcer disease
• Severe heart failure
• History of gastrointestinal bleeding or perforation
• Severe hepatic impairment
• Severe renal impairment

Adverse effects

• Gastrointestinal disturbances (nausea, vomiting, diarrhea, constipation)
• Headache
• Dizziness
• Rash
• Elevated liver enzymes
• Renal impairment
• Anaphylactic reactions
• Increased risk of cardiovascular events

Interactions

• Increased exposure when used with regorafenib (severe interaction)

Precautions

• Use with caution in patients with a history of gastrointestinal disorders
• Monitor renal function in patients with compromised renal function
• Caution in patients with cardiovascular diseases
• Caution in the elderly, who may be more susceptible to adverse effects

Pregnancy

Mefenamic acid should be avoided during pregnancy, especially in the third trimester due to risks of fetal cardiovascular effects and potential complications.

Breast-feeding

Use with caution; mefenamic acid is excreted in breast milk, but significant effects on the nursing infant are not expected.

Storage

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

Formulations

• Capsules
• Tablets
• Oral suspension