Diflunisal

Diflunisal

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Systematic (IUPAC) name
2',4'-difluoro-4-hydroxybiphenyl-3-carboxylic acid
Clinical data
Pregnancy category	AU: C US: C (Risk not ruled out)
Routes of administration	Oral
Legal status
Legal status	UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	80-90%
Protein binding	>99%
Metabolism	Hepatic
Biological half-life	8 to 12 hours
Excretion	Renal
Identifiers
CAS Number	22494-42-4
ATC code	N02BA11 (WHO)
PubChem	CID 3059
DrugBank	APRD00922
ChemSpider	2951
Chemical data
Formula	C13H8F2O3
Molar mass	250.198 g/mol[[]]
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'Diflunisal' is a generic NSAID (non-steroidal anti-inflammatory drug). It was developed by Merck Sharp & Dohme in 1971 after showing promise in a research project studying more potent chemical analogs of aspirin. It was first sold under the brand name Dolobid, marketed by Merck & Co., but generic versions are now widely available. It is available in 250 mg and 500 mg tablets.

Mechanism

Like all NSAIDs, Diflunisal acts by inhibiting the production of prostaglandin , a hormone which is involved in inflammation and pain. There is also an antipyretic effect, but this is not a recommended use of the drug. Though diflunisal has an onset of 1 hour, and maximum analgesia at 2 to 3 hours, the diflunisal plasma levels will not be steady until repeated doesages are achieved. The long plasma half-life is a distinctive feature of diflunisal in comparison to similar drugs. To increase the rate at which the diflunisal plasma levels become steady, a loading dose is usually used. It is primarily used to treat symptoms of arthritis, and for acute pain following oral surgery, especially removal of wisdom teeth.

Effectiveness of diflunisal is similar to other NSAIDs, but duration of action is twelve hours or more. This means fewer doses per day are required for chronic administration. In acute use, it is popular in dentistry when a single dose after oral surgery can maintain analgesia until the patient is asleep that night.

Side Effects

The inhibition of prostaglandins also has the effect of decreasing the protection given to the stomach from its own acid. Like all NSAIDS, this leads to an increased risk of stomach ulcers, and their complications, with long-term use.

Overdose

Deaths that have occurred from diflunisal usually involved mixed drugs and or extremely high dosage. The oral LD₅₀ is 500 mg/kg. Symptoms of overdose include coma, tachycardia, stupor, and vomiting. The lowest dose without the presence of other medicines which caused death was 15 grams. Mixed with other medicines, a death at 7.5 grams has also occurred. Diflunisal usually comes in 250 or 500 mg, thus it is relatively hard to overdose by accident.

Indicated for: Pain, mild-moderate Osteoarthritis Rheumatoid arthritis Injury to tendons Inflammation Do not cut/crush/chew. Monitor blood pressure. Use lowest effective dose for shortest duration.

Side effects: Cardiovascular: Irregular heart beat (!) This medication may increase risk of serious and potentially fatal cardiovascular thrombotic events, MI, and stroke (!) Risk may increase with duration of use (!) Increased risk for Cardiovascular disease history (!) Contraindicated for Heart Bypass peri-op pain (!) Ear, nose, and throat: Ringing in the ears (!) Eye: Yellowing of eyes (!) Gastrointestinal: Increased risk of serious GI adverse events including bleeding, ulceration, and stomach or intestine perforation which can be fatal: may occur at any time during use and without warning. Elderly at greater risk for serious GI events (!) Abdominal pain and cramps Constipation Gas & Flatulence Diarrhea Nausea & Vomiting Dyspepsia Central Nervous System: Drowsiness Dizziness Headache Insomnia Fatigue Somnolence Psychiatric: Nervousness Skin: Swelling of the feet, ankles, lower legs, and hands (!) Yellowing of skin (!) Rash Ecchymosis Contraindications: Hypersensitivity to aspirin/NSAID-induced asthma or urticaria Aspirin triad Pregnancy 3rd trimester CABG surgery (peri-op pain) Cautions: Cardiovascular disease Cardiac risk factors Hypertension Congestive Heart Failure Elderly or debilitated Impaired liver function Impaired kidney function Dehydration Fluid retention GI bleed history/PUD Asthma Coagulopathy Smoker Corticosteriod use Anticoagulant use Alcohol use Diuretic use ACE Inhibitor use Prolonged use Precautions: If symptoms labeled, (!), appear, stop usage immediately and contact your doctor. Overdose is possible and deaths have occurred. Do not take while on other pain medications. Do not take while pregnant or breast feeding.

External links

• http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a684037.html
• http://www.medsafe.govt.nz/Profs/Datasheet/discontinued/ansaltab.htm
• Dolobid Prescribing Information (manufacturer's website)
• Dolobid Medication Guide (manufacturer's website)
• Diflunisal (patient information)
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