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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.
Ref: Annals of Int Med 132(2) Jan 2000
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