Efficiency in pain control is often taken as a yardstick to assess a medical/ dental practitioner by patients. Effective pain relief can be achieved with oral non-opioids and non-steroidal anti-inflammatory drugs. These drugs are appropriate for many post-traumatic and post surgical pains, especially when patients go home on the day of the operation.
It is disheartening that in the selection of analgesics, tradition and ill informed prejudice sometimes hold sway over evidence and common sense. Analgesic efficiency is expressed as the Number Needed to Treat (NNT) i.e., the number of patients who need to receive the active drug to achieve at least 50% relief of pain in one patient compared with placebo, over a six-hour treatment period.
To calculate NNT
1. Calculate the percentage of people who have the desired outcome in the treatment group. E.g., 80/200 X 100 = 40% (80 got relief in 200 patients)
2. Calculate the percentage of people who have the desired outcome in the placebo or control group. E.g., 40/200 X 100 = 20%
3. Take (2) away from (1) to give the percentage of people helped by the treatment. e.g., 40- 20 =20
4. Divide 100 by this percentage to give the NNT. E.g., 100/20 =5
The most effective drugs have a low NNT of about 2, meaning that for every two patients who receive the drug, one patient will get at least 50% relief because of the treatment (the other patient may obtain relief but it does not reach the 50% level).
For paracetamol 1gm, the NNT is nearly 5. Combinations of paracetamol 650mg with dextropropoxyphene 65mg (e.g., Poxy plus, Novamed) improves the NNT slightly. Ibuprofen is better at 3 and diclofenac (e.g., Oxalgin, Zydus Cadila ) at about 2.5.
These NNT comparisons are against placebo, the best NNT 2 means that while 50 of 100 patients will get at least 50% relief because of the treatment, another 20% will have a placebo response which then gives at least 50% relief, so that with diclofenac 70 out of 100 will have effective pain relief.
If the patients can swallow, it is best to prescribe drugs to be taken orally. Of the oral analgesics, Non Steroidal Anti Inflammatory Drugs (NSAID) perform best, and paracetamol alone or in combination are also effective.
Some of the NSAIDs are Ketoprofen, Aspirin, Naproxen, Indomethacin, Ketorolac, Piroxicam, Celecoxib, Meloxicam, Mefenemic acid, Rofecoxib, Diclofenac and Nimeluside.
Celecoxib (e.g., Zycel, Zydus Cadilla and Colcibra from Ranbaxy ), Rofecoxib (e.g., Toroxx 25 from Torrnet pharma and Rofact from Sun pharma), Meloxicam (e.g., Melogesic, Lupin) and Nimesulide (e.g., Nimbid, Astra-IDL) belong to a new family of NSAIDs. They are referred to as cyclooxygenase-2 (COX-2) inhibitors. Celecoxib has been approved for treatment of rheumatoid arthritis in USA, and rofecoxib is approved for treatment of acute pain.
Adverse effect data on NSAIDs from long term dosing, where gastric bleeding is the main worry, rates ibuprofen the safest. Gastrointestinal ulcers and bleeding are side effects of traditional NSAIDs that block COX-1 and COX-2. Both COX-1 and COX-2contribute to inflammatory response. In the gastrointestinal mucosa, COX-1 plays and important role. Prostaglandins such as prostaglandin E2 (PGE2) that are produced from COX-1 derived PGH2 protect gastrointestinal lining against ulceration.
Because traditional NSAIDs inhibit COX-1 and COX-2, they decrease gastrointestinal synthesis of prostaglandin (predisposing patients to GI ulceration) and production of platelet thromboxane A2 (predisposing patients to bleeding).
Though clinical data on GI toxicity of celecoxib and rofecoxib are limited, they are encouraging and show approximately 1% absolute risk reduction for symptomatic ulcers. Post marketing surveillance should help clarify the actual risk for serious ulcer complications with these new COX-2 inhibitors and reveal other non-gastrointestinal toxic reactions that result from their use
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