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CLINICALFEATURE
by Dr Bertrand Chew
Post-Minor Oral Surgery Pain
Management with Oral Medication
Pof Analgesics, there are the Acetaminophen,
ain control is of paramount importance in post surgical
management. The common drugs groups used are
Analgesic and Anti-inflammatory Drugs. In the family
Acetylsalicylic acid, NSAIDs(inclusive of the COX II-inhibitors)
and the Opioids.
In the pharmaceutical control of pain in the oral region, it acts
on the pain pathways at different levels. The Spinothalamic
(trigeminal-thalamic) tract is that carries the sensation of pain.
The Chemical pathways of pain involves a cascade of events in
cells, involving products of cells, enzymes, soluble factors, and
blood vessels and their contents (Enwemeka & Spielholz 1992;
Schmidt et al 1994; Tillman & Cummings 1992).
Acetaminophen, 4'-hydroxyacetanilide, is an analgesic and
antipyretic which occurs as a white, odorless, crystalline
powder, possessing a slightly bitter taste. It has the following
molecular formula C8H9NO2 with a molecular weight of
151.16. It is discovered by accident when a similar molecule
(acetanilide) was added to a patient’s prescription
approximately 100 years ago. The medication is commonly
known as Paracetamol = para-acetyl-amino-phenol.
To date, the exact mode of action is still being discussed. The
pain-reducing effect is more directly on the central nervous
system by increasing the threshold of pain. There is an
inhibition of the actions of chemical mediators that sensitize the
pain receptors to mechanical or chemical stimulation. It also
blocks activity by reducing the active oxidized form of cyclooxygenase
to an inactive form and hence has little
inflammatory actions (Lucas R et al 2005). The antipyretic
activity is exerted by blocking the effects of the chemical
pyrogen on the hypothalamic heat-regulating center.
Others mention inhibition of nitric oxide formation that results
from activation of substance P and N-methyl-D-aspartate
(NMDA) receptor stimulation. Acetaminophen is metabolized by
the liver. Therefore drugs that increase the action of liver
enzymes that metabolize acetaminophen (eg carbamazepine,
isoniazid, rifampin) may decrease the action of acetaminophen.
The potential for acetaminophen to harm the liver is increased
when it is combined with alcohol or drugs that also harm the
liver. Acetaminophen is used in all stages of pregnancy. Breastfeeding
is not a contraindication. (Gramham et al 2005)
Drug Safety
There is no clear evidence that taking paracetamol causes
asthma, but more studies are suggesting that may be some
association. Studies of patients with asthma suggest that
acetaminophen challenge can precipitate a decline in FEV(1) >
15% among sensitive individuals. (Eneli et al 2005). Some
patients may have a specific sensitivity to the active ingredient
or to any of the other components of the paracetamol.
Paracetamol can be combined with many other drugs.
They include the following:
1. Orphenadrine citrate-analgesic properties. Also possesses
anti-cholinergic actions. Good for muscle aches. (Aanarex)
2. Caffeine (Panadol Extra)
3. Codeine Phosphate (Panadeine)
4. both codeine and Caffeine. (PACOFEN)
5. Pamabrom: a diuretic to ease water retention. (for
menstrual)
6. Tramadol (Ultracet)
Acetylsalicylic acid is commonly known as Aspirin. The chemical
name 2-(acetyloxy) benzoic acid, are used as an analgesic,
antipyretic and anti-inflammatory. It has also an anticoagulant
effect and is used in long-term low-doses to prevent heart
attacks. The bitter powder is extracted from willow bark that
could ease aches and pains and reduce fevers. It was further
modified by by researcher Arthur Eichengrun and Felix Hoffmann
in1897.Aspirin was patented on March 6, 1899 by Bayer.
Aspirin suppresses the production of prostaglandins and
thromboxanes. This happens because cyclooxygenase (COX),
an enzyme that participates in the production of prostaglandins
and thromboxanes, is irreversibly inhibited when aspirin
acetylates it. This makes aspirin different from other NSAIDS,
which are reversible inhibitors. (John Robert Vane 1982).
The topic on the safety of extractions on ling term aspirin
patient has been discussed many times. The following
statement would be a very useful guide: The scientific literature
does not support routine discontinuation of oral anticoagulation
therapy for dental patients (Jeske et al 2003).The
management of oral surgery procedures on patients treated
with anti-coagulants should be influenced by several factors:
extent and urgency of surgery, laboratory values, treating
40 Dental Asia • May / June 2008