Lesson E2 - Over-the-Counter (OTC) Drugs

Question 1

Over-the-counter (OTC) drugs are sold to the general public without a physician’s prescription
based on the premise that the general public are able to

Answer 1

diagnose mild symptoms and to select appropriate agents to treat these symptoms.

Question 2

OTCD

Answer 2

Any drug that can be purchased without a physician’s prescription. The general public often
does not consider these agents as drugs.

Question 3

The sale of OTC drugs is controlled by a section of the Food and Drug Act. The Act controls
safety, efficacy, advertising and sale of these products. All OTC drugs must undergo

Answer 3

rigid safety assessment.

Question 4

Acetylsalicylic acid (ASA):

Answer 4

This compound has been widely used for well over a century. The compound possesses
analgesic (reduces pain), antipyretic (reduces fever), and anti-inflammatory (reduces
inflammation) properties. In appropriate doses, the drug is effective for pain, fever and
inflammation.

Question 5

The mechanism of action of ASA for all three effects is that it inhibits synthesis of
prostaglandins, endogenous substances which enhance the mediation of pain, fever and

Answer 5

have a role in inflammation.

Question 6

The major toxicity of ASA is gastric irritation which occurs in

Answer 6

2% of the population

Question 7

ASA
breaks down the mucosal protective barrier in the stomach and leads to irritation and increased
bleeding. This is a serious problem when ASA is taken chronically in high doses. Enteric
coated ASA tablets will reduce the gastric irritation, but the onset of action is slow and are not
useful for relief of pain but are useful in

Answer 7

chronic inflammation

Question 8

ASA is associated with Reyes

syndrome in children when it is given during

Answer 8

fever

Question 9

An additional use for ASA is in the prevention of strokes and myocardial infarcts. Low dose
ASA has been shown to reduce the risk of these serious diseases. The mechanism is to inhibit
platelet aggregation and hence

Answer 9

clot formation.

Question 10

Acetaminophen was first introduced into therapeutics in 1877 but did not gain popularity until
the 1950’s. Acetaminophen is an analgesic and antipyretic, and is equal in efficacy to ASA for
these two effects. Unlike ASA, acetaminophen is not

Answer 10

anti-inflammatory.

Question 11

The mechanism of action is similar to that of ASA, i.e. it inhibits prostaglandin synthetase, the enzyme responsible for the

Answer 11

formation of postaglandins.

Question 12

At therapeutic doses, acetaminophen is very well tolerated; it does not cause

Answer 12

gastric irritation.

Question 13

Ibuprofen is a non-steroidal, anti-inflammatory agent which appeared as an OTC product in the
early 1990’s. Ibuprofen is an effective analgesic and antipyretic as well as an

Answer 13

anti-inflammatory

compound.

Question 14

The mechanism of

action of ibuprofen is a reversible

Answer 14

inhibition of the synthesis of prostaglandins.

Question 15

Naproxen

This recent addition to the OTC group of analgesics, is an effective analgesic, antipyretic and
anti-inflammatory agent. It may well emerge as the most effective OTC anti-inflammatory agent
available. It is an inhibitor of

Answer 15

prostaglandin synthesis

Question 16

ASA, acetaminophen and ibuprofen are often used in combination with other ingredients and
analgesics. A popular combination is either ASA or acetaminophen with codeine and caffeine.
The rationale for these mixtures is to obtain additional analgesic effects from drugs which act by

Answer 16

different mechanisms. ASA and acetaminophen act peripherally (sensory pain nerves) and
codeine acts at the level of the central nervous system (brain and spinal cord). Acetaminophen,
ASA and codeine in combination is a “rational mixture”, e.g. “222”, but the dose of codeine is
small and increased efficacy over ASA alone has not been fully documented.

Question 17

There is no known cure for the common cold. Treatment is directed at relieving the symptoms.
The drugs most commonly used are:

Answer 17

decongestants, antitussives, antihistamines, expectorants,

and analgesics.

Question 18

Antihistamines:

Answer 18

Drugs which block the histamine receptor (H1) and prevent histamine from producing
vasodilation and inflammation

Question 19

Most antihistamines have anticholinergic properties (atropine-like) and this may aid in reduction
of secretions. Anticholinergics (atropine) decrease nasal and salivary secretions. In terms of
efficacy, antihistamines have a very limited role in alleviating the

Answer 19

symptoms of a cold

Question 20

Decongestants:

These compounds are all α-adrenergic receptor stimulants (agonists), and when they activate the
α receptor, they cause vasoconstriction and a reduction in

Answer 20

congestion. Phenylephrine, and pseudoephedrine sympathomimetic α receptor agonists are the agents most
commonly used.

Question 21

Problems with local decongestants include rebound congestion; long-term use leads to

Answer 21

chronic

rhinitis and local irritation.

Question 22

Codeine and dextromethorphan HBr are two widely used, centrally-acting (medulla) cough

Answer 22

suppressants.

Question 23

Expectorants are substances that

Answer 23

stimulate secretions in the bronchial tree and loosen the phlegm in the upper airway passages. The agent most commonly used is glyceryl guaiacolate – it is of
questionable value.

Question 24

Analgesics are effective in reducing the fever and the achy feeling associated with the cold.
Drugs of choice are ASA or acetaminophen; acetaminophen may be a

Answer 24

better choice

Question 25

Sun protection factor (SPF):

SPF = minimum erythema dose (UV) of sunscreen-protected skin
_________________________
minimum erythema dose (UV) of unprotected skin

Minimum erythema dose is the time of exposure to UV radiation that will cause a

Answer 25

burn or

reddening of the skin

Question 26

Systemic antacid, e.g. sodium bicarbonate, is absorbed by the G.I. tract and can cause systemic
alkalosis. Calcium carbonate is also absorbed (about 10%) and can increase Ca2+
load and is

Answer 26

used as a source of calcium.

Question 27

Non-systemic antacid is not absorbed and does not cause

Answer 27

systemic alkalosis

Question 28

Sodium bicarbonate is very widely used by the public in home remedies. It very rapidly

Answer 28

neutralizes acid in the stomach.

Question 29

Aluminum Hydroxide is a non-systemic antacid that is in the form of insoluble complexes and
thus has a

Answer 29

slow onset of action.

Question 30

Magnesium hydroxide is widely used as an antacid and cathartic. It is a non-systemic antacid.
Magnesium hydroxide reacts with acid in the stomach very rapidly and has a more rapid onset of
action that aluminum hydroxide. It has

Answer 30

good neutralizing capacity.

Question 31

Histamine is involved in the release of gastric acid. The histamine receptors in the acid secreting
cells of the stomach are distinct from those which cause allergies. The receptor in the stomach
has been designated H2. Famotidine and ranitidine are relatively new drugs which block the H2
receptors and reduce the amount of acid secreted. These agents are more effective than

Answer 31

antacid

in reducing acid and are more convenient to take

Question 32

Laxative effect:

Answer 32

Excretion of a soft formed stool, may have increased peristalsis or increased
hydration of the stool.

Question 33

Cathartic effect:

Answer 33

Implies a more fluid evacuation. The effect always involves increased motor
activity of the G.I. tact.

Question 34

Adsorbents – Kaolin and pectin (Kaopectate and related products). Add bulk to the G.I. tract
and may absorb toxins. The absorbents are useful to control the acute

Answer 34

symptoms of self-limiting

diarrhea.

Question 35

OTC preparations can produce a number of drug interactions with other drugs.

Answer 35

1. Antihistamines are CNS depressants and will cause additive CNS depression with alcohol,
   narcotic analgesics and other CNS depressants.
2. Decongestants – sympathomimetics are contraindicated (should not be used) with
   monoamine oxidase inhibitors. Monoamine oxidase inhibitors will prevent the metabolism
   of the decongestant and hence increase its concentration in the body and the response is exaggerated
3. ASA given with oral anticoagulants may produce bleeding. ASA displaces some drugs
   from plasma protein binding sites. In addition, ASA prevents platelets from adhering to
   each other. Platelets adhering to each other is necessary to stop a cut from bleeding.
4. Antacids will interfere with absorption of some drugs, e.g. tetracyclines. Antacids will
   bind to the tetracyline preventing absorption.
5. Mineral oil used as a laxative will retard the absorption of a number of drugs. Mineral oil
   is not absorbed and any drug that is dissolved in the mineral oil will not be absorbed

Question 36

Selection of an OTC Product

Answer 36

1. Select the product that has the simplest formulation (single ingredient).
2. Select a product with a therapeutically effective dose.
3. Select a product that lists all the ingredients and their amounts.
4. Select a good generic, if available.
5. Be wary of gimmicks. Fancy preparations such as Bufferin have no added benefits over
   conventional products.
6. Select the appropriate dosage form, e.g. liquid for children. Palatability must be
   acceptable

Question 37

What over-the-counter drugs should be readily available?

Answer 37

1. Ibuprofen as an anti inflammatory.
2. Acetaminophen as an analgesic and antipyretic.
3. 0.5% hydrocortisone cream.
4. A second generation antihistamine.
5. Famotidine or an antacid.
6. Kaolin and pectin.
7. Pseudoephedrine.
8. Rubbing alcohol to cleanse wounds.
9. Dextromethorphan HBr
10. Loperamide