TX-MF TABLETS

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

Indications

• Heavy menstrual bleeding (menorrhagia)
• Surgical procedures to reduce blood loss
• Trauma-related bleeding
• Hereditary angioedema
• Dental procedures in patients with bleeding disorders

Dosage

Children: Refer to the BNF for Children for specific dosing guidelines based on age, weight, and indication.

Adults: Refer to the BNF for specific dosing guidelines based on indication and patient condition.

Mechanism of action

Tranexamic acid competitively inhibits the lysine binding sites on plasminogen, preventing its conversion to plasmin. This inhibition decreases fibrinolysis, leading to increased clot stability and reduced bleeding.

Pharmacodynamics

The primary pharmacodynamic effect of tranexamic acid is its ability to reduce bleeding by stabilizing fibrin clots. The drug exhibits a dose-dependent effect on clotting, with higher doses leading to a more pronounced antifibrinolytic effect. Tranexamic acid does not significantly affect platelet function or coagulation factors.

Pharmacokinetics

Tranexamic acid is rapidly absorbed after oral administration, with peak plasma concentrations occurring within 1 to 3 hours. It has a bioavailability of approximately 30% to 50%. The drug is primarily excreted unchanged in the urine, with a half-life of approximately 2 hours. It does not undergo significant metabolism in the liver, which is beneficial in patients with hepatic impairment.

Contra-indications

• Active venous thromboembolism
• History of thromboembolic disorders
• Severe renal impairment
• Hypersensitivity to tranexamic acid or any excipients

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Dizziness
• Headache
• Visual disturbances
• Thrombosis
• Hypotension
• Allergic reactions

Interactions

• Anticoagulants (increased risk of thrombosis)
• Hormonal contraceptives (increased risk of thrombosis)
• Fibrinolytics (increased risk of bleeding)

Precautions

• Monitor for signs of thrombosis during treatment
• Use with caution in patients with a history of seizures
• Caution in patients with renal impairment
• Assess the risk of bleeding before use

Pregnancy

Tranexamic acid should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Tranexamic acid is excreted in breast milk; caution should be exercised when administered to nursing mothers.

Storage

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

Formulations

• Tablets
• Injection solution