Over-The-Counter
Drugs
(Ch. 14)
OVER-THE-COUNTER
(OTC) DRUGS ARE A BIG BUSINESS IN THE UNITED STATES
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OTC drugs are those
which are self-prescribed and self-administered for the relief of self-diagnosed
illnesses
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The FDA estimates
that consumers self-treat four times more health problems than doctors
treat, often using OTC drugs
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Americans spend
over $18 billion a year on OTC products
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The two biggest
markets are for aspirin-like analgesics and for the collection of cough,
cold, and flu products
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The 1962 Kefauver-Harrris
amendment required that all drugs be evaluated for both safety and efficacy.
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The FDA reviews
each active ingredient - in 1972, they divided OTC products into 26 classes
and appointed an advisory panel for each class to decide for each ingredient
whether there is evidence indicating that it is safe and effective for
its purpose, and also to decide what sorts of claims could be made for
that ingredient on the label
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The FDA classifies
these as being "generally recognized as safe" (GRAS) and/or "generally
recognized as effective" (GRAE)
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"safe" means "a
low incidence of adverse reactions or significant side effects under adequate
directions for use and warnings against unsafe use as well as low potential
for harm which may result from abuse"
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In 1985, the FDA
began to publish "Tentative Final Monographs" on each class - to solicit
comments from the public and drug companies before publishing Final Monographs
- this has been an immense task.
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By 1992, only 34
of the proposed 71 monographs had become finalized (it's not clear whether
the remaining Tentative Final Monographs are becoming more final or more
tentative as the process continues)
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As advisory panels
made tentative decisions, they were communicated to the manufacturers,
who were encouraged to change their formulations
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In 1992, the US
General Accounting Office released a critical report claiming that the
FDA still didn't know exactly how many OTC products are being marketed
and still couldn't guarantee that everything being sold is both safe and
effective.
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By the 1990s the
list of therapeutic classes had grown from 26 to over 80 (today the number
of OTC products is still not known - perhaps more than 100,000)
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In 1997, the FDA
proposed to create uniform standards for labels, with a minimum print size,
topics in a consistent order (active ingredients, directions for use, warnings),
with bold, bulleted headings, and make the language more understandable
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A drug is permitted
for OTC sale unless, because of potential toxicity or for other reasons,
it may be safely sold and used only under a prescription. Sometimes the
only difference between an OTC product and a prescription product is the
greater amount of active ingredient in each prescription dose. More often,
prescription drugs are chemicals that are unavailable OTC.
PSYCHOACTIVE
OTC PRODUCTS
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The only OTC stimulant
allowed by the FDA is caffeine; there are many "look-alikes" to resemble
prescription stimulants, such as metamphetamine
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phenylpropanolamine
(PPA) has a molecular structure similar to that of amphetamine and ephedrine
is the only drug in weight-control products, the others pass off as "health
foods". The recommended dose for appetite suppression is 75 mg per day.
There is some concern about the safety of this dose, with the threat being
increased blood pressure resulting from sympathetic stimulation
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A few years ago,
most sleep aids contain small amounts of the antihistamine methapyrilene
- then in 1979, it was reported that methapyrilene caused cancer in laboratory
animals, so it was no longer GRAS.
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Today, most antihistamines
are used as OTC sleep aids — diphenhydramine is the active ingredient in
most products
ANALGESICS
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Two major classes
of drugs are used to reduce pain or the awareness of pain: anesthetics
and analgesics. The latter are compounds that reduce pain selectively without
causing a loss of other sensations.
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The analgesics are
divided into two groups: opiates and OTC internal analgesics (aspirin,
acetaminophen, and ibuprofen)
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There are two types
of pain: visceral (narcotics are effective pain relievers) and somatic
(salicylates are effective)
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Placebos have also
been effective in reducing pain (35% of patients in one study). It was
found that placebos are most effective in reducing pain in stressful situations.
Internal analgesics have shown to be more effective at therapeutic doses
than placebos for certain kinds of pain
SALICYCLATES
ARE THE MOST WIDELY USED CLASS OF INTERNAL ANALGESICS
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In 1859, salicylic
acid was synthesized - the major difficulty is that it caused stomach discomfort.
In 1898, acetylsalicylic acid was synthesized - - it provided relief
from pain without stomach upset. The compound was tested, patented and
released for sale in 1899 as Aspirin. Taken orally, aspirin is a more potent
analgesic than salicylic acid, because it does not irritate the stomach
as much and thus is absorbed more rapidly
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In 1915, the 5 gram
(325 mg) white tablet stamped "Bayer" first appeared and aspirin became
a nonprescription item
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Aspirin has three
major therapeutic uses — to block somatic pain, as an antipyretic agent
(reducing fever at the temperature-regulating area of the hypothalamus),
and as an anti-inflammatory agent
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Some aspirin preparations
have been buffered with additional ingredients meant to neutralize
the acidity of aspirin. This has two effects: 1) to reduce stomach irritation,
and 2) by moving the aspirin more rapidly into the intestine (faster absorption
rate than the stomach), to produce faster relief
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The therapeutic
dose for aspirin is generally considered to be in the range of 600 - 1,000
mg
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Aspirin also has
some negative side effects such as: 1) increasing the bleeding time by
inhibiting blood platelet aggregation, 2) inducing gastrointestinal bleeding,
3) Reyes syndrome affecting people under the age of 20, usually after they
have had viral infections (overall mortality rate is ~25%). No one knows
what causes Reyes syndrome (check with your physician), and 4) overdose
poisonings.
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Aspirin modifies
the the cause of pain. Prostaglandins are local hormones that are manufactured
and released when cell membranes are distorted or damaged. The prostaglandins
work on the ends of neurons that mediate pain in the injured areas. The
prostaglandins sensitize the neurons to mechanical stimulation and to stimulation
by two other local hormones histamine and bradykinin. Aspirin blocks the
synthesis of the prostaglandins.
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As an antipyretic:
specific prostaglandins act on the anterior hypothalamus to decrease heat
dissipation through the normal procedures of sweating and the dilation
of peripheral blood vessels. Aspirin blocks the synthesis of this prostaglandin
ACETAMENOPHEN
AND IBUPROFEN
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Acetaminophen (aspirin-like
analgesic and antipyretic) is as effective as aspirin in reducing pain
as long as dosage limits are carefully observed, overuse can result in
fatal liver damage
-
Ibuprofen (aspirin-like
analgesic and anti-inflammatory) is the ingredient in other new pain-relieving
drugs. Since the discovery that aspirin and similar drugs work by inhibiting
the synthesis of prostaglandins. The most common side-effects of ibuprofen
are gastrointestinal: nausea, stomach pain and cramping in addition to
fatal liver damage with overdose. Ibuprofen was the first of several new
drugs that are now collectively referred to as "non-steroidal anti-inflammatory
drugs" (NSIDs)
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More products of
this nature can be expected in the future
ALMOST EVERYONE
SUFFERS FROM A COLD SOME TIME
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A common cold is
caused by any one of many viruses - two groups of viruses are known to
be associated with colds: the rhinoviruses and the coronaviruses
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These viruses zero
in on the upper respiratory tract, at first causing irritation that can
lead to reflex coughing and sneezing. Increased irritation inflames tissue
and is followed by soreness and swelling of the mucous membranes - as a
defense mechanism, the mucous membranes releases fluid that causes post-nasal
drip that irritates the throat
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Colds are not completely
preventable, but there are four things you need to know to help you avoid
the cold virus: 1) up to 100 times as many virus particles are produced
and shed from the nasal mucosa as from the throat, 2) there are few virus
particles in saliva, Viruses survive on dry skin and non-porous surfaces
for about 3 hours, and 4) most cold viruses enter the body through the
nostrils and eyes (via the hands). Therefore wash your hands frequently
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Interferon has been
used with good results in the prevention of cold symptoms
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Choosing the correct
OTC drug may mean reading the labels and doing comparison shopping. There
are three common types of ingredients in modern cold remedies: antihistamines
(for a runny nose and sneezing), nasal decongestants (for relief of swollen
membranes in the nasal passages - sympathomimetics), and analgesic-antipyretics
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NOTE: Table 14.2
in your book - DECONGESTANTS should be above (Sympathomimetic)