CHAPTER 9
ANALGESICS: DRUGS FOR PAIN RELIEF
"REAL PAIN CAN ALONE CURE US OF
IMAGINARY ILLS. WE FEEL A THOUSAND MISERIES TILL WE ARE LUCKY ENOUGH TO FEEL
REAL MISERY."
Samuel Taylor Coleridge
INTRODUCTION
The term analgesia literally means
"without pain," thus, the principal therapeutic purpose of the
internal analgesics is to alleviate the discomforts of pain. There are a
variety of drugs that have analgesic properties,
however, many of these are unsuitable for OTC use because of their serious side
effects. For example: general anesthetics (e.g., ether) while being good
analgesics, also render the patient unconscious; narcotics (e.g.,
morphine, codeine) are excellent analgesics, but these drugs can severely
depress respiration (breathing) and can possess high abuse potential. Actually,
only three classes of analgesic drugs are considered sufficiently safe to be
marketed over-the-counter; these are the aspirin-like drugs (salicylates), acetaminophen, and ibuprofen-like
drugs. These internal analgesics account for approximately $3 billion in
sales each year and are the most frequently used OTC medications in the United States. In fact, the majority of American adults use a
nonprescription analgesic at least once a month. These drugs are generally
effective in the treatment of mild to moderate somatic (musculoskeletal)
pain, but are usually ineffective in the treatment of either severe pain
or pain that originates from the internal organs (visceral pain).
Although these agents are predominantly
employed in the treatment of pain, they also possess pharmacological properties
that make them useful in the treatment of other problems (see discussion
below); consequently, they are included in both single-ingredient and
multiple-ingredient products that are promoted for the treatment of several,
seemingly unrelated, health problems.
Many of the actions of the OTC analgesics
probably occur because they block the synthesis of the natural body chemicals
called prostaglandins. The prostaglandin compounds are produced locally
throughout the body and help to mediate a variety of physiological processes
such as pain, inflammation, and fever.
ANALGESIA
OTC internal analgesics are very useful in
the treatment of mild to moderate somatic (musculoskeletal) pains associated
with the muscles, bones, skin, teeth, and nerves. Whereas visceral pains that
originate from the internal organs (e.g., heart, stomach, intestines, and
kidneys etc.) or severe pains (regardless of their origin) are usually
unresponsive to treatment with these agents. The following are examples of
specific types of pains that generally can be relieved by administering OTC
analgesics.
Headaches are probably the most common pains for which
nonprescription analgesics are used. In fact, 80% of the adult population self
medicate with OTC drugs to relieve headache discomfort. These agents generally
can provide relief from the usual headaches caused by tension (associated with
excessive muscle tightness in the head and neck areas), or sinus pressure
(associated with colds and allergies). The OTC analgesics usually provide
little or no relief from the excruciating discomfort of the severe pain
resulting from vascular headaches like migraines; however, a recent study found
that patients who used 300 mg of aspirin every other day experienced 20% fewer
migraine headaches.
Myalgias are the
aches and cramps associated with the muscles and are often caused by over
exertion. Myalgias can be significantly relieved with
the use of OTC internal analgesics. In addition, muscle discomfort is often
associated with common ailments such as colds and flu: these myalgias also can be treated effectively by administering
nonprescription pain-relieving drugs.
Arthralgias (joint pains) are pains that occur in bone joints throughout the body, but most often are
associated with the legs and arms. Because of the effectiveness of the OTC
analgesics against skeletal pain, it is not surprising that many arthralgias are relieved by taking OTC analgesics.
Miscellaneous pains that are diminished with the use of OTC products
containing analgesics include toothaches, sprains, sunburns, and neuralgias
(pain from nerve endings).
It is important to remember that before
attempting to eliminate any pain, the cause of the discomfort should be
identified. Pain is an essential warning signal whereby the body informs us
that something is wrong. Analgesics do not eliminate the source of the
discomfort, but merely mask the problem by alleviating the painful symptoms. If
pain persists for more than a few days and its cause remains unidentified,
professional assistance should be sought. Self-medication of OTC analgesics is
only intended for the relief of self-limiting pains that are associated with
medical conditions that require no treatment or prior diagnosis by a health
professional.
ANTIPYRETIC (ANTIFEVER)
The OTC analgesics are frequently used to
lower elevated high body temperatures (fevers) associated with a variety of
illnesses such as colds and flus. Treatment with
these drugs can help to reduce, and sometimes eliminate, a fever, but does not
alter its cause.
Some experts fear that the public has become
over zealous in the treatment of fever with OTC antipyretics, especially in
young children. It has been suggested that an elevated body temperature assists
the body to fight disease-causing infections. If this hypothesis is correct,
the act of eliminating fevers with nonprescription drugs might actually
aggravate the medical problem. Consequently, most physicians recommend
conservative use of the OTC analgesics to reduce elevated body temperatures.
They suggest that such treatment should not be rendered except in cases of high
fevers that exceed 102-103 degrees F.
ANTIINFLAMMATORY
Inflammation is a response by the body that
is associated with an injury or the rejection of a local irritant or foreign
material. It is usually characterized by localized pain, redness, swelling, and
tissue heat. Such symptoms can be relieved with the use of high doses of
aspirin-like or ibuprofen-like drugs, whereas acetaminophen possesses little or
no antiinflammatory action. Because high
doses of these drugs are required, the treatment of inflammatory conditions
such as arthritis should only be attempted with the guidance of a physician.
For example, arthritis is an inflammatory disease characterized by degeneration
of the joints. High doses of the salicylates or
ibuprofen are used by many arthritic patients to relieve the inflammatory
discomfort. It should be mentioned, however, that while the administration of
these agents can reduce the arthritic pain and swelling, they do not alter the
long-term bony deterioration associated with arthritis.
DRUG PROPERTIES
SALICYLATES (ASPIRIN-LIKE DRUGS)
Aspirin belongs to a family of drugs known
as the salicylates, all of which are chemically related
and when dissolved in water they assume their medically active form. The orally
administered compounds include:
acetylsalicylic acid (aspirin)
salicylic acid
salicylate salts (sodium, choline,
and magnesium)
Of these agents, acetylsalicylic acid (aspirin)
is the most commonly used in OTC products. Methyl salicylate
is another drug related to the salicylate chemical
group; however, its toxicity makes it unsuitable for internal use. It is a
liquid having the characteristic odor and taste of oil of wintergreen, which is
used in salves and liniments for the external treatment of painful muscles and
joints. Because of its distinct smell it is attractive to young kids and can be
a problem as a pediatric poison; thus, it should be used with caution around children.
ADVERSE EFFECTS
The oral salicylates
are relatively nontoxic, yet the potential for serious consequences does exist.
Acute toxicity: These
undesirable effects result from a single, large dose of a salicylate.
This is most likely to occur accidentally in children under 5 years of age.
However, the incidence of acute salicylate
intoxication has diminished. This is likely due to the presence of safety (child-proof)
caps on the aspirin bottles and recommendations against using aspirin products
for children (see discussion on Reye's Syndrome
below).
Chronic (multiple doses) toxicity: While
this occurs in both adults and children, related problems are very different.
Adult - this is usually associated with long-term use of
high doses of salicylates. Typically
seen in patients using these compounds to treat arthritis. The toxic
effects include: mental confusion, ringing in the ears, nausea, vomiting,
headache, and dizziness.
Child - chronic salicylate
intoxication is particularly serious in children because their bodies are very
sensitive to the adverse effects of these compounds. Although
this use to be a major emergency problem, because most parents no longer give
aspirin to their children it has dramatically diminished. The side
effects of chronic aspirin overdose in children include fever, hyperventilation
(rapid breathing), aggravation of coughing, and irregular breathing.
Gastrointestinal irritation: Salicylate compounds are very irritating to the stomach and
often cause nausea and indigestion. Approximately 5% of those taking
usual analgesic doses (300-700 milligrams) of a salicylate
drug will suffer an upset stomach. Some OTC salicylate
products are promoted as being buffered in order to reduce this problem;
however, there is no scientific evidence to substantiate their claims. One
effective approach to reduce stomach upset is to take the salicylate
product with food or liquid. This dilutes the drug and helps to provide a
protective coating for the stomach lining.
Individuals with particularly sensitive
stomachs or a chronic gastrointestinal condition, such as ulcers, should avoid
using salicylate-containing products. In addition,
patients who are suffering from arthritis tend to have a higher incidence of
gastrointestinal irritation from aspirin. Gastric irritation can be reduced by
encasing the tablet in an enteric coating that does not dissolve until after
passing through the stomach into the small intestine (e.g., Ecotrin).
As a result, the enteric-coated aspirins are commonly used by patients with chronic
stomach problems.
Allergy: The
problem of allergic reaction to salicylates has
likely been overestimated in the past. Less than 0.2% of the general population
is truly allergic to aspirin. Possibly some people who suffer from stomach
irritation when they consume salicylate products are
incorrectly considered to be allergic to the drug. The types of allergic
responses seen are described in Chapter 2. Interestingly, there is a
higher rate of aspirin allergy in patients who suffer from asthma. It is not
clear why.
Bleeding: Administration of aspirin-like drugs will increase
the time required for a clot to form in the blood and prolongs the bleeding
time following damage to a blood vessel. This effect requires only 300-600 mg of
aspirin (1-2 tablets) and persists for up to 5-7 days. Aspirin has a greater anticlotting effect than other salicylates.
Although this anticlotting
effect can cause blood loss of 2-6 ml per day from the gastrointestinal tract
in the stools, it has little practical significance in the normal person.
However, this effect can have serious bleeding consequences in individuals who
(1) already have a bleeding disorder, (2) have a history of bleeding ulcers,
especially if they routinely drink alcohol, (3) are anticipating surgery within
7 days, (4) are pregnant and ready to deliver, or (5) are taking anticoagulant
(blood-thinning) prescription drugs. It is believed that the aspirin-induced
delay of blood clotting actually is beneficial in patients prone to suffering
heart attacks (see Prevention of Heart Attacks below).
Link with Reye's Syndrome: Reye's
syndrome is a rare and often fatal children's disease which can cause damage to
the brain, liver, and other vital organs. Reye's syndrome seems to follow mild
cases of influenza, chicken pox, a common cold and other viral infections and
is characterized by severe vomiting and lethargy that might progress to
delirium and coma. Although the exact cause of Reye's syndrome is unknown,
several studies have associated the occurrence of this disease with aspirin
use. The evidence for such a link is so convincing that, as of 1988, the
following warning, advising consumers of this association, has been required on
all OTC products which contain aspirin-like agents.
Warning: Children and teenagers should not use this medicine
for chicken pox or flu symptoms before a doctor is consulted about Reye's
syndrome, a rare, but serious disease reported to be associated with aspirin.
Some pediatricians feel that the danger of
aspirin to children is great enough that they recommend only non-aspirin
analgesics be used until the child reaches 16 years of age. Interestingly,
during 1986-1991 the rate of Reye's Syndrome in the United States declined markedly. This dramatic decrease was likely
due to efforts by the Public Health Service to inform the public about the
relationship between Reye Syndrome and aspirin use as well as FDA-mandated
label warnings on aspirin products alerting consumers to the problem.
Use during pregnancy: The FDA has warned pregnant women not to use aspirin
during the last three months of their pregnancy. Possible problems include
effects by aspirin on fetal circulation and uterine contraction. Products
containing aspirin are required by FDA regulation to include the following
warning on their labels
It is especially important not to use
aspirin during the last 3 months of pregnancy because it may cause problems in
the unborn child or complications during delivery.
PREVENTION OF HEART ATTACKS
In a study involving 22,000 male American
physicians between the ages of 40 and 84, aspirin, a dose of one tablet
(approximately 300 mg) every other day, was shown to significantly reduce
mortality from cardiovascular disease. The rate of first heart attacks was 47%
less in those using aspirin compared to those taking placebo. A similar study
concluded in 1991, examined the effects of aspirin in women. Risk
of heart attacks were reduced significantly for women aged 50 years and
older. Although these results are impressive, it is not recommended that
everyone begin taking aspirin on a daily basis to prevent heart attacks. While
aspirin is a relatively safe drug, it does have significant side effects (as
noted above). Consequently, use of aspirin for prevention of cardiovascular
disease is recommended only for those who have existing predisposing factors.
For example, the benefit of aspirin would likely outweigh its risks when used
by males above 35 years of age with known cardiovascular risk factors such as
elevated blood pressure, high cholesterol, a history of cigarette smoking, or a
family history of premature cardiovascular disease. However, for others (e.g.,
a young woman without risk factors and with a family history relatively free of
cardiovascular disease) the risks likely outweigh the benefits.
It is a good idea to first consult with a
physician before beginning a program of regular aspirin use. The recommended
doses for cardiovascular uses are generally, 50 to 325 milligrams once daily
(75 to 325 milligrams for individuals who have angina and/or have had a
previous heart attack). Higher doses of aspirin do not provide greater
protection and, in fact, might actually counteract the beneficial effects.
Because the benefits of aspirin in this regard are likely due to the effects of
this agent on clotting, use of other drugs which retard clotting, such as
ibuprofen, might also be beneficial in the prevention
of cardiovascular disease; however, drugs such as acetaminophen (Tylenol),
which do not alter clotting mechanisms would have no such benefit.
In addition to preventing cardiovascular
disease, research shows that taking an aspirin when symptoms of a heart attack
begin significantly improves the chances of survival. It is important to note,
however, that if any heart attack warning signs occur, an individual should
call 9-1-1 immediately.
After the call to 9-1-1, an aspirin should be taken unless the victim has an allergy to aspirin
or a condition that makes using it too risky. Taking aspirin isn't advised
during a stroke, because not all strokes are caused by blood clots. Most
strokes are caused by clots, but some are caused by ruptures. Taking aspirin
could actually make these bleeding strokes more severe
ASPERGUM
Aspargum is a chewing gum product which contains aspirin. It
is promoted as a convenient dosage form for aspirin, especially in the
treatment of sore throats. Each piece of gum contains 228 mg of aspirin. It
should be noted that many clinicians feel that aspirin has no topical,
analgesic effect. In other words, no relief from the soreness of an inflamed
throat will occur due to bathing it in aspirin. In fact, the local irritating
properties of the aspirin could actually aggravate the pain. If relief does
occur, it is likely due to absorption of the aspirin once it reaches the
stomach. It's a cute gimmick, but not much more.
ACETAMINOPHEN
Acetaminophen (active ingredient in products
such as Tylenol, and Aspirin Free Excedrin) in 1995 accounted for
more than $1 billion in sales. This analgesic is chemically unrelated to the salicylates even though it possesses some of the same
pharmacological properties. There are also important differences between
acetaminophen and salicylate that give each type of
agent a unique therapeutic role.
THERAPEUTIC EFFECTS
Analgesic and Antipyretic properties: These
properties are basically the same for both acetaminophen and the salicylates, although some studies suggest that
acetaminophen is a slightly inferior analgesic for some pains.
Antiinflammatory activity: Acetaminophen does not
possess antiinflammatory activity and would not be
effective in the treatment of inflammatory conditions such as arthritis.
ADVANTAGES OVER ASPIRIN AND
SALICYLATES
Acetaminophen does not irritate the
gastrointestinal tract.
Individuals allergic to aspirin are probably
not allergic to acetaminophen.
Acetaminophen can be packaged in pleasant
tasting liquids for young children or the elderly. Aspirin is not available in
this form due to its instability in liquids (aspirin rapidly decomposes in
water).
Acetaminophen has no apparent link with the
incidence of Reye's Syndrome.
Acetaminophen does not alter the blood
clotting process and has no effect on bleeding time.
Because of these differences, acetaminophen
can often be used in patients who are adversely affected by aspirin
administration.
ADVERSE EFFECTS
Acetaminophen is a remarkably safe drug when
used as recommended. However, due to a recent surge in popularity the quantity
of acetaminophen-containing products found in homes has increased. With this
greater availability has come a dramatic rise in the cases of accidental and
intentional poisonings with acetaminophen. For example, 5% of the total drug
poisoning in this country involve acetaminophen.
It is important to understand that large
doses of this analgesic can be very toxic. Liver damage occurs when a single
dose of 10 grams of acetaminophen is consumed and the damage can cause death if
20 grams or more of the drug get into the body. Recent studies have also
suggested that chronic use of moderate doses of acetaminophen can be toxic to
individuals who already have liver damage, such as alcoholics or persons with a
history of hepatitis. Consequently, warnings have been placed on the labels of
acetaminophen products concerning the possibility of liver damage due to interactions
with alcohol. For example, people who are binge drinkers, or consume three or
more drinks a day are advised not to use acetaminophen.
IBUPROFEN
Ibuprofen was originally approved for
marketing in the United States as an antiinflammatory
drug in 1974. Until the summer of 1984, it was only available by prescription
and sold under the proprietary names of Motrin and Rufen.
When it was first marketed, it was used primarily in the treatment of
inflammatory diseases such as arthritis; however, as the analgesic properties
of this drug became evident, it was employed extensively in the treatment of
pain. Because of a relatively safe track record, the FDA ruled that ibuprofen
could be available as an OTC analgesic medication and is currently available under
several brand names, such as Advil and Nuprin.
There is no pharmacological difference between the OTC and prescription
ibuprofen products. However, OTC ibuprofen can only be purchased as 200 mg
tablets, whereas, ibuprofen marketed as a prescription medication is available
as 400, 600 or even 800 mg tablets.
As an OTC analgesic, ibuprofen has become
very popular. It currently accounts for more than 25% of the nation's annual
OTC sales of pain relievers.
THERAPEUTIC EFFECTS
The pharmacological features of this agent
are similar to those of the salicylates in that it possess analgesic, anti-inflammatory and antipyretic
properties. One important difference is the analgesic capability: ibuprofen has
been shown to be more effective against moderate somatic pain than other OTC
analgesic compounds. The ceiling analgesic effect of this drug is usually
reached with doses of 400 mg and for most patients with mild to moderate pain
there may be no need for larger doses. In addition, this agent is particularly
effective in relieving the cramps and discomforts associated with menstruation
(called dysmenorrhea): the starting dose for
treatment of this condition is somewhat higher than for other aches and pains,
often requiring 400-800 mg followed by 200 mg every 4-6 hours as needed.
Ibuprofen continues to be carefully
evaluated in order to determine if the public is substantially benefited by the
reclassification of this effective drug to OTC status. But judging by its
popularity, it appears to be well accepted by the public and is a valuable
addition to the OTC analgesic drug group. In fact, in 1997 after 10 years of
study, the FDA found ibuprofen to be safe and effective in children and allowed
the marketing of the first pediatric ibuprofen product (50 mg/tablet).
ADVERSE EFFECTS
Most experts agree that ibuprofen is safer
in overdosages than either aspirin or acetaminophen.
But this does not mean ibuprofen is without side effects. Some of its adverse
actions resemble those of aspirin and include the following:
Gastrointestinal - usually better tolerated than aspirin, but can
cause stomach irritation. Those at greatest risk of experiencing G.I. problems
are the elderly, women, ulcer suffers and malnourished or underweight
individuals.
Menstruation - some reports of delays in menstruation occurring
when ibuprofen is used immediately prior to the female period. It may also
increase the menstrual flow.
Kidney - ibuprofen has some potential for causing kidney
damage, particularly in the elderly or individuals with cardiovascular
problems, diabetes, or kidney disease.
Heart - because ibuprofen causes sodium (element in table
salt) retention, it can aggravate certain cardiovascular diseases such as
hypertension.
Bleeding - ibuprofen can prolong bleeding time, however, this
effect is less severe and of shorter duration than that associated with the salicylates.
NAPROXEN
Another analgesic addition to the OTC market
is naproxen, marketed since 1976 under the trade name Naprosyn.
Because of its long history of safe and effective use, naproxen was approved as
a nonprescription analgesic ingredient by the FDA in 1994. This drug is
currently being manufactured under the OTC brand name, Alleve.
Alleve was an immediate success with sales
approaching $100 million during its first 6 months of marketing.
Alleve is indicated for the relief of minor pain associated
with the common cold, headache, toothache, muscle aches, backache, arthritis,
menstrual cramps and to reduce fever. Its effects and side effects are very
similar to those of ibuprofen, although its onset of action tends to be slower
and its duration of action tends to be longer. The productís
label recommends that adults take one tablet 8 to 12 hours, not to exceed 3
tablets a day.
KETOPROFEN
The most recent ibuprofen-like analgesic
drug to be switched to OTC status is ketoprofen
(Orudis). Its features are similar to
ibuprofen, although it is substantially more potent; thus, 12.5 mg of ketoprofen has pain-relieving properties comparable to 200
mg of ibuprofen. This does not mean ketoprofen is
more effective or has a greater plateau effect; it
only means ketoprofen tablets are much smaller and
easier to swallow. The convenience of the smaller tablets might be significant
for the elderly.
SELECTING OTC ANALGESICS
"Bayer works wonders"; "More
doctors use Tylenol"; "Advil stops the painí; and, "All day
strong-all day long (Alleve)." These are a few
examples of the hype used by manufacturers to promote almost 200 different
analgesic products. What are the real options and what factors should be
considered when making a selection?
GENERAL CONSIDERATIONS
It is either salicylates,
acetaminophen or ibuprofen-like:
No matter how the manufacturers promote their OTC analgesics, this fact remains,
the principal active ingredients in all OTC analgesic products are either salicylates (aspirin-like), acetaminophen, or
ibuprofen-like. If one product costs substantially more than a competitor, it
is probably due to the brand name and not the pharmacological properties of its
ingredients. You can usually purchase an inexpensive generic OTC analgesic and
be fairly confident that the product will be as effective as high-priced
brands. However, one should still avoid purchasing analgesics with broken
tablets, tablet powder, improperly applied labels, or aspirin-containing
products with a vinegar smell: these signs suggest a product with inferior
quality.
Some efforts have been made to compare the
pain-relieving properties of the three basic OTC analgesic compounds. These
studies suggest that ibuprofen-like drugs possess the greatest analgesic
capability (similar to a codeine plus aspirin combination) followed by aspirin
with acetaminophen close behind. However, it is important to note that there is
a great deal of individual variation; thus, it is impossible to generalize for
everyone which compound is the best.
Analgesic combinations: To
justify a high price for their analgesic products, some manufacturers combine
aspirin with acetaminophen, other salicylates, or
with another pain-relieving ingredient (plus many millions of dollars worth of
promotion) and try to convince the public that OTC combination products are
better than plain aspirin or plain acetaminophen. Do not be fooled!
There is no proven therapeutic benefit derived from combining these analgesic
ingredients. Analgesic combinations such as Excedrin (salicylate plus acetaminophen) have been found to have no
special advantage over plain aspirin, tablet for tablet.
"High Potency" Analgesics: Manufacturers
of OTC analgesics have misled the public into believing that the more salicylate or acetaminophen that is squeezed into a single
tablet or capsule, the better the product. There are currently OTC medicines on
the market that contain as much as 500 mg of analgesic per unit. This is
considerably more than 325 mg found in most of the analgesic preparations.
Examples of this promotional approach
include:
Alka-Seltzer Caplets (500 mg acetaminophen)
Bayer Aspirin Extra Strength (500 mg aspirin)
Maximum Strength Anacin (500 mg aspirin)
Anacin Aspirin Free (500 mg acetaminophen)
Tylenol Extra Strength (500 mg acetaminophen)
For most people and pains, this dosage is
inconvenient and leads to unnecessary consumption of the drug. Bearing in mind
that the plateau dose for the analgesic effect of aspirin or acetaminophen is
600-700 mg, it is of no therapeutic advantage to exceed that dose when trying
to relieve pain. For example, a person is forced to take 2 tablets of the
"High Potency" analgesics (total of 1000 mg of drug) in order to
achieve maximum pain relief; thus, the person consumes an excess of 300 mg of
the drug needlessly. A greater concern is that the presence of the "High
Potency" analgesics in households has increased the incidence and severity
of accidental analgesic intoxication.
A possible advantage of the high-dose
analgesic products is in the treatment of arthritis, or other inflammatory
condition. Much higher doses of salicylates are
required for antiinflammatory action,
consequently, tablets with 500 mg of drug would be more convenient than the
traditional doses of approximately 300 mg.
Analgesics in combination with other
drugs: Salicylates and acetaminophen are commonly sold in combination
with other active drugs such as :
Caffeine - Caffeine is a mild CNS stimulant (see Chapter 5)
frequently included in OTC analgesic products (e.g., Anacin, Excedrin).
Whether or not this drug has analgesic action itself has been controversial.
However, recent studies have suggested that doses of 60-100 mg of caffeine
might provide relief from some types of minor pains and enhance the analgesic
action of salicylates and acetaminophen. In addition,
some patients notice a slight burst of energy after consuming
caffeine-containing drug products similar in nature to that associated with
drinking a cup of coffee. Such a lift might cause some distraction from the
discomforts of pain and reinforce subsequent use of the analgesic.
One particular therapeutic advantage of a
caffeine-analgesic combination might be the treatment of vascular headaches. As
previously mentioned, the pain associated with this type of headache is likely
due to pressure from vasodilation. Caffeine has
vasoconstrictor properties and its administration has been shown to reduce the
pain associated with some mild vascular headaches.
Narcotics - Narcotics are prescription analgesics used to
treat moderate to severe pain. Because of potentially severe side effects
(e.g., inhibition of breathing, abuse potential) it is desirable to use the
smallest effective dose of these agents as possible. It has been found that the
analgesic effect of narcotics plus aspirin or acetaminophen
are supra-additive (synergistic). In other words, when narcotics are
administered together with aspirin or acetaminophen, the total analgesia is
greater than if their effects were merely additive.
This allows significant reductions in the amount of narcotics administered
without compromising pain relief. This synergism likely is due to the fact the
mechanisms whereby narcotics relieve pain is much different than the OTC
analgesics. The narcotics enhance the endorphin (natural pain relievers) system
and block the relay of the pain message in the spinal cord as well as alter its
aversive processing in the pain center of the brain. Narcotics frequently used
in combination with aspirin or acetaminophen include:
codeine
oxycodeine
pentazocine
propoxyphene (Darvon)
Antacids (buffered aspirin) - The addition of antacid ingredients is intended to reduce
the gastric irritation caused by aspirin-like analgesics; such combinations are
commonly referred to as buffered aspirin (e.g., Bufferin).
Actually, the small amount of antacid in most buffered aspirin products is
unlikely to significantly alter the irritating effects of aspirin on the
stomach. Even though some users claim they can tolerate buffered preparations
better than plain aspirin, their claims are not supported by well controlled
clinical studies.
A second rationale for including so-called
buffering ingredients in a product is to speed up the absorption of the aspirin
into the body from the stomach and thus achieve more rapid relief. Technically,
this objective is achieved due to the presence of the antacids; however, with
normal usage the effect is so minor that it is probably therapeutically
insignificant.
CONCLUSION
The selection of an OTC analgesic that is
best suited for a therapeutic task is based upon (1) the type of pain, (2) the
severity of pain, (3) the side effects of the drug and, (4) the medical history
of the consumer. For example, the ibuprofen-like drugs tend to be the most
effective, the acetaminophen-containing drugs the best tolerated, and the
aspirin-containing drugs the least expensive. Many other factors that have been
discussed previously should also be considered when making an analgesic
selection.
It is important that consumers not be
deceived by the unsubstantiated claims of the manufacturers. Even though they
try to convince the public that each of their OTC analgesic products is
therapeutically unique, it usually is not true. This fact was the basis of a
decision by the Federal Trade Commission that several drug companies must stop
their deceptive advertisements for analgesic products such as Bayer
Aspirin, Vanquish, Cope, Midol, Bufferin,
and Excedrin. Based on this ruling, claims of superior performance or
safer action are not permitted.
COMMON OTC ANALGESICS
PRODUCT DOSAGE
ASPIRIN
Bayer, Regular Strength 325 mg
Bayer, Adult Low Strength 81 mg
Ecotrin, Regular Strength 325 mg
St. Joseph Low Dose
Adult Aspirin 81 mg
Anacin Caplets/Tablets 400 mg
Bufferin Arthritis Strength 500 mg
Anacin Maximum Strength 500 mg
ACETAMINOPHEN
Anacin Aspirin Free 500 mg
Tylenol 325 mg
Tylenol for children 80 mg
Tylenol Junior Strength 160 mg
IBUPROFEN
Advil 200 mg
Advil Children 50 mg
Motrin IB 200 mg
Children's Motrin (drops or chewable) 50 mg
Nuprin 200 mg
NAPROSYN
Aleve 200 mg
KETOPROFEN
Actron 12.5 mg
Orudis 12.5 mg
SELECTED COMBINATION OTC ANALGESICS
Arthriten Tablets acetaminophen, magnesium salicylate
Excedrin Extra Strength acetaminophen,
aspirin, caffeine
Excedrin Migraine acetaminophen, aspirin,
caffeine