Over-the-counter medicines, also known as non-prescription medicines, are in high demand nowadays. The demand for OTC pain relievers is very high. OTC medicines relieve mild to moderate pain, reduce fever, and decrease inflammation, and these medicines are readily available and affordable in the market. However, not many people are fully aware of how these medicines actually work in our bodies. There are several types of OTC pain relievers, each with its own mechanism of action. The most common types of OTC painkillers are non-steroidal anti-inflammatory drugs (NSAIDs).
Arachidonic acid is produced from phospholipids in the presence of phospholipase A2. Prostaglandins and leukotrienes are produced from arachidonic acid. Prostaglandins are produced in the presence of cyclooxyrgenase, while leukotrienes are produced in the presence of lipoxygenase. Prostaglandins are responsible for pain and inflammation. NSAIDs inhibit cyclooxyrgenase, thereby reducing pain and inflammation.
COX-1 is mainly present in the gastrointestinal tract (GIT), while COX-2 and COX-3 are present in the brain and kidneys.
NSAIDs inhibit COX enzymes and decrease the synthesis of prostaglandins. NSAIDs have antipyretic and anti-inflammatory activity. The only NSAID without anti-inflammatory activity is Paracetamol. Paracetamol is a COX-3 inhibitor, which is why it does not exhibit inflammatory properties.
NSAIDs increase the risk of gastric irritation because nonselective COX inhibitors are present in the gastrointestinal tract, and these COX inhibitors are responsible for gastric irritation. Selective COX-2 inhibitors reduce the risk of gastric irritation with long-term therapy. However, these selective COX-2 inhibitors are contraindicated for cardiovascular disease, ischemic heart disease, and kidney dysfunction.
The most commonly used NSAID is Ibuprofen. The OTC dose of Ibuprofen is 1200mg/day. Ibuprofen helps to reduce inflammation and acts as an analgesic. However, Ibuprofen is a non-selective COX inhibitor, which is why it can irritate the stomach. This is why nonselective COX inhibitors are always taken with proton pump inhibitors.
