Non –steroidal anti-inflammatory drugs (NSAIDS)-Fenamic acids

Name of the Fenamic acids

1. Meclofenamate

Mechanism of Action

Blocks cyclooxygenase, the enzyme needed to synthesize prostaglandins, which mediate the inflammatory response and cause local vasodilation, swelling, and pain. By inhibiting prostaglandins, this NSAID reduces inflammatory symptoms. It also relieves pain because prostaglandins promote pain transmission from periphery to spinal cord.

Pharmacokinetics

• Peak plasma time: 0.5-2 hr
• Peak plasma concentration: 4.8 mcg/mL
• Metabolism: Extensively metabolized to an active metabolite (Metabolite I; 3-hydroxymethyl metabolite of meclofenamic acid) and at least 6 other less well-characterized minor metabolites
• Half-life: 0.8-5.3 hr (single dose); 0.8-2.1 hr (TID x14 days); 15 hr (Metabolite I)
• Clearance: 206 mL/min
• Excretion: 70% urine; ~30% feces via biliary excretion

Contraindications

Hypersensitivity to aspirin, iodides, meclofenamate, other NSAIDs, or their components

Adverse Reactions

• CNS: Dizziness, drowsiness, fatigue, headache, insomnia, seizures, stroke
• CV: Hypertension, MI, peripheral edema, tachycardia
• EENT: Stomatitis, tinnitus
• GI: Abdominal pain; anorexia; constipation; diarrhea; diverticulitis; dyspepsia; dysphagia; elevated liver function test results; esophagitis; flatulence; gastritis; gastroenteritis; gastroesophageal reflux disease; GI bleeding, perforation, and ulceration; hepatic failure; indigestion; jaundice; melena; nausea; perforation of stomach or intestines; stomatitis; vomiting
• GU: Acute renal failure, dysuria, elevated BUN and serum creatinine levels
• HEME: Agranulocytosis, anemia, easy bruising, hemolytic anemia, leukopenia, neutropenia, pancytopenia, thrombocytopenia
• RESP: Asthma, respiratory depression
• SKIN: Erythema multiforme, pruritus, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria
• Other: Anaphylaxis, angioedema

Nursing Considerations

• Use meclofenamate with extreme caution in patients with a history of ulcer disease or GI bleeding because NSAIDs such as meclofenamate increase risk of GI bleeding and ulceration. Expect to use drug for shortest time possible in these patients.
• Be aware that serious GI tract ulceration, bleeding, and perforation may occur without warning symptoms. Elderly patients are at greater risk. To minimize risk, give drug with food and a full glass of water. If GI distress occurs, withhold drug and notify prescriber immediately.
• Use meclofenamate cautiously in patients with hypertension and monitor blood pressure closely throughout therapy. Drug may cause hypertension or worsen it.
• Monitor patient—especially if he’s elderly or taking meclofenamate long-term—for less common but serious adverse GI reactions, including anorexia, constipation, diverticulitis, dysphagia, esophagitis, gastritis, gastroenteritis, gastroesophageal reflux disease, hemorrhoids, hiatal hernia, melena, stomatitis, and vomiting.
• Monitor liver function test results because, rarely, elevations may progress to severe hepatic reactions, including fatal hepatitis, liver necrosis, and hepatic failure.
• Monitor BUN and serum creatinine levels in elderly patients, patients taking diuretics or ACE inhibitors, and patients with heart failure, impaired renal function, or hepatic dysfunction; drug may cause renal failure.
• Monitor CBC for decreased hemoglobin and hematocrit because drug may worsen anemia
• Assess patient’s skin regularly for rash or other hypersensitivity reaction because meclofenamate is an NSAID and may cause serious skin reactions without warning, even in patients with no history of NSAID sensitivity. At first sign of reaction, stop drug and notify prescriber.
• Expect lower doses of meclofenamate to be used for long-term therapy.

Patient Teaching

• Tell patient to take drug with a full glass of water to keep it from lodging in esophagus and causing irritation. Suggest taking drug with food or milk to avoid GI distress.
• Instruct patient to report itching, rash, severe diarrhea, and swelling in ankles or fingers.
• Caution patient to avoid hazardous activities until drug’s CNS effects are known.
• Caution pregnant patient not to take NSAIDs such as meclofenamate during last trimester because they may cause premature closure of fetal ductus arteriosus.
• Explain that meclofenamate may increase risk of serious adverse cardiovascular reactions; urge patient to seek immediate medical attention if signs or symptoms arise, such as chest pain, shortness of breath, weakness, or slurring of speech.
• Explain that meclofenamate may increase risk of serious adverse GI reactions; stress importance of seeking immediate medical attention for such signs and symptoms as epigastric or abdominal pain, indigestion, black or tarry stools, or vomiting blood or material that looks like coffee grounds.
• Alert patient to rare but serious skin reactions to meclofenamate. Urge him to seek immediate medical attention for rash, blisters, itching, fever, or other indications of hypersensitivity

REFERENCES

1. Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
2. McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
3. April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
4. Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
5. Nursebro.com, Search – Nursebro

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