II. Mechanism
- History
- Willow bark and wintergreen leaves contain Salicin (Salicylic acid)
- Used for thousands of years for pain and fever
- Salicylic acid was first lab synthesized in the 1840s
- Salicylic acid was acetylated to the more palatable Acetylsalicylic Acid (Aspirin) in the 1850s
- Salicylates have been used for pain, fever and rheumatic diseases for more than 100 years
- Willow bark and wintergreen leaves contain Salicin (Salicylic acid)
- Salicylates have antipyretic, Analgesic and anti-inflammatory properties
- Blocks cyclooxygenase (COX, esp. COX1)
- Inhibits conversion of Arachidonic Acid to Prostaglandin precursors
- Decreasing Prostaglanding levels results in decreased fever, pain and inflammation
- Salicylates (esp. Aspirin) also have antiplatelet activity
III. Medications
-
Acetylsalicylic Acid (Aspirin)
- Analgesic Dosing: 500-1000 mg every 4-6 hours
- Other less commonly used Salicylates
- Trisalicylate (Trilisate)
- Dosing 1000-1500 mg every 8-12 hours
- Diflunisal (Dolobid) 500 mg every 8-12 hours
- Risk of Acute Interstitial Nephritis
- Compared with Aspirin, lower risk of Gastrointestinal Bleeding, Tinnitus
- Salsalate (Disalcid)
- Arthritis (OA, RA): 3000 mg/day divided every 8 to 12 hours
- Trisalicylate (Trilisate)
- Other Salicylates not in use medically
IV. Adverse Effects
- Gastrointestinal upset
- Gastrointestinal Bleeding
- Tinnitus
- Hypersensitivity
- Serious skin reactions (e.g. Stevens-Johnson Syndrome)
V. Safety
- Avoid Salicylates in general in Lactation
- Most Salicylates, as with NSAIDs are legacy system Pregnancy category C (except Category D in third trimester)
- Aspirin is used in pregnancy for Preeclampsia Prevention
- However Salicylates and NSAIDs have significant risks in pregnancy
- See NSAID for pregnancy-related risks that also apply to Salicylates
- Salicylates have specifically been found to have adverse effects in pregnancy
- Anemia
- Anti-partum Hemorrhage
- Post-partum Hemorrhage
- Prolonged gestation
- Complicated deliveries
- Perinatal mortality
- Collins (1975) Lancet 2(7930):335-8 +PMID: 51142 [PubMed]