Diflunisal

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Introduction

Generic Name: Diflunisal
Brand Names: Dolobid®
Chemical Formula: C13H8F2O3
Drug Class: Nonsteroidal Anti-inflammatory Drug (NSAID)

Diflunisal is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain and reduce inflammation. Unlike aspirin, diflunisal is a derivative of salicylic acid and is typically prescribed for managing moderate pain and inflammatory conditions, particularly when long-term treatment is required.

Primary Uses of Diflunisal

  1. Pain Relief:
    It is usually prescribed for treating moderate pain, such as that resulted from musculoskeletal injuries, dental procedures, or post-surgical discomfort.
  2. Chronic Inflammatory Conditions:
    It is generally used to manage chronic inflammatory conditions like osteoarthritis and rheumatoid arthritis. By reducing swelling and inflammation in the joints, it can help improve the mobility and decrease pain.
  3. Antipyretic Effect:
    Though not often used as a first-line treatment for fever, it can lower fever in cases where inflammation is the root cause.
  4. Amyloidosis:
    In addition to its primary uses for pain and inflammation, diflunisal has shown promise in managing a rare condition called transthyretin amyloidosis (ATTR amyloidosis). This condition occurs when abnormal proteins (amyloid fibrils) build up in various organs, leading to dysfunction. The drug helps by stabilizing the transthyretin protein, slowing down the formation of these harmful fibrils. While it’s not a cure, it can help delay the progression of the disease and improve quality of life in patients, especially those with familial amyloid polyneuropathy (FAP).

    Though newer treatments specifically targeting ATTR amyloidosis, like tafamidis, are available, diflunisal remains a valuable option, especially when other therapies may not be suitable.

Mechanism of Action

Diflunisal works by inhibiting the cyclooxygenase (COX) enzymes, specifically COX-1 and COX-2. These enzymes are responsible for producing prostaglandins, which are the molecules that trigger inflammation, pain, and fever. By blocking prostaglandin synthesis, it reduces both pain and inflammation.

Pharmacokinetics

  • Absorption: It is absorbed relatively slowly but completely from the gastrointestinal tract after oral administration. Peak plasma concentrations occur around 2 to 3 hours after dosing.
  • Metabolism: It undergoes metabolism primarily in the liver through conjugation with glucuronic acid to form inactive metabolites.
  • Excretion: The drug is primarily excreted by the kidneys. Around 90% of the drug is eliminated within 72 hours.
  • Half-life: The elimination half-life is approximately 8 to 12 hours, which allows for twice-daily dosing.

Pain and Inflammation

  1. Musculoskeletal Pain:
    Diflunisal is effective in relieving pain associated with muscle strains, sprains, and minor injuries. Its extended half-life allows for longer-lasting pain relief compared to many other NSAIDs.
  2. Arthritis:
    It is frequently used to manage chronic joint pain and inflammation in conditions such as osteoarthritis and rheumatoid arthritis. This drug reduces swelling in the joints, thereby improving flexibility of joints and thus reducing discomfort.
  3. Dental Pain:
    It is sometimes prescribed after dental procedures like tooth extractions or surgery to manage pain and reduce inflammation.

Dosage and Administration

  • For Pain Relief:
  • Adults: The typical starting dose for pain relief is 500 mg, followed by 250 mg every 8 to 12 hours, depending on the severity of pain. The maximum recommended daily dose is 1,500 mg.
  • For Arthritis:
  • Adults: A maintenance dose of 250 to 500 mg twice daily is commonly prescribed for managing arthritis symptoms. Dosing may be adjusted based on individual response and tolerability.
  • The doctors may decide the dosing and interval as per the condition and symptoms of the patient.

Diflunisal should be taken with food or a glass of water to minimize gastrointestinal discomfort. Always follow the dosage instructions provided by your healthcare provider.

Side Effects of Diflunisal

Like any medication, diflunisal may cause side effects, particularly when used long-term or in high doses.

  • Common Side Effects:
    • Stomach pain, indigestion, or heartburn.
    • Drowsiness or dizziness.
    • Mild rash or skin irritation.
  • Serious Side Effects:
    • Gastrointestinal Bleeding: As with other NSAIDs, it can cause stomach or intestinal bleeding, particularly in individuals with a history of ulcers.
    • Kidney Problems: Prolonged use can impair kidney function, leading to reduced urine output or swelling in the legs.
    • Allergic Reactions: Symptoms of an allergic reaction, such as swelling, hives, or difficulty breathing, require immediate medical attention.

Contraindications of Diflunisal

Diflunisal is contraindicated in the following situations:

  • Allergy to NSAIDs: Individuals allergic to aspirin or other NSAIDs should avoid diflunisal.
  • Gastrointestinal Disorders: Patients with a history of peptic ulcers or gastrointestinal bleeding should not take diflunisal, as it increases the risk of these conditions worsening.
  • Severe Kidney or Liver Disease: This drug can further compromise kidney or liver function, making it unsuitable for patients with severe kidney or liver disorders.
  • Pregnancy (Third Trimester): Like other NSAIDs, diflunisal should be avoided during the third trimester of pregnancy due to the risk of premature closure of the ductus arteriosus in the fetus.

Drug Interactions

Diflunisal can interact with several medications, which may increase the risk of side effects or reduce the effectiveness of treatment:

  • Anticoagulants (e.g., Warfarin): Combining diflunisal with blood thinners increases the risk of bleeding.
  • Other NSAIDs or Corticosteroids: Using multiple anti-inflammatory medications together raises the risk of gastrointestinal bleeding and kidney problems.
  • ACE Inhibitors and ARBs: This drug may reduce the effectiveness of medications used to control blood pressure, particularly ACE inhibitors.
  • Diuretics: It may also reduce the effectiveness of diuretics, potentially leading to fluid retention.

Warnings and Precautions

  1. Gastrointestinal Risk: Long-term use of diflunisal can increase the risk of stomach ulcers and bleeding. Taking it with food can help reduce these risks.
  2. Cardiovascular Risk: As with many NSAIDs, prolonged use may increase the risk of heart attack or stroke, especially in individuals with pre-existing cardiovascular conditions.
  3. Kidney Function: It can reduce blood flow to the kidneys, leading to impaired kidney function, especially in older adults or those with a pre-existing kidney disease.

When to Contact a Doctor

Consult a healthcare provider if you experience:

  • Unexplained stomach pain or black, tarry stools, which may indicate gastrointestinal bleeding.
  • Unusual swelling, rapid weight gain, or decreased urine output
  • Chest pain, shortness of breath, or slurred speech
  • Allergic reactions, such as difficulty breathing, rash, or swelling.

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