Lesson B4 - Pharmacology

Question 1

Opium contains at least 20 different

chemical compounds, two of which are

Answer 1

morphine and codeine, are analgesic (pain-relieving) drugs.

Question 2

In the early 1800’s, morphine was isolated as the major analgesic agent from

Answer 2

opium

Question 3

The purification of morphine revolutionized the use of opiates. Since then, morphine has been used worldwide for the treatment of

Answer 3

pain and diarrhea.

Question 4

The term “opioid” refers to

Answer 4

any natural or synthetic substance which exerts actions on the body
that are similar to those induced by morphine and that are antagonized (blocked) by the drug
naloxone.

Question 5

Opioids include:

Answer 5

1. Opiate narcotics (analgesic agents obtained from the opium poppy).
2. Substances structurally related to morphine.
3. Synthetic drugs with structures different from that of morphine.
4. Endogenous brain peptides that exert analgesic actions (opioid peptides: enkephalins and
   endorphins) .

Question 6

There are now at least three known families of

endorphins; these are:

Answer 6

enkephalins, dynorphins and β-endorphins.

Question 7

There are several types of opioid receptors; three will be discussed…

Answer 7

1. Mu (µ) receptors are present in all structures in the brain and spinal cord
2. Kappa (k) receptors are involved in analgesia, dysphoria and miosis (pin-point pupils)
3. Delta (δ) receptors have as their endogenous ligand, the enkephalins

Question 8

Opioid receptors are located in the

Answer 8

peripheral as well as the central nervous system-These are located in the gastrointestinal tract and are responsible for the constipation caused by opiates.

Question 9

Agonists:

Answer 9

Illicit a full response.
Natural – morphine and codeine
Semi-synthetic – heroin
Synthetic – meperidine and methadone

Question 10

Mixed Agonists/Antagonists:

Answer 10

Pentazocine is the best example of this group. This group can illicit a response when given alone, but can block part of the
response to morphine, when given together with morphine.

Question 11

Antagonists:

Answer 11

These agents block the response to morphine, heroin and other
opiates at the respective receptor. Administration of an antagonist to an addict will precipitate “withdrawal”.

Question 12

The prototype antagonist is naloxone. It has no analgesic activity
and is used in:

Answer 12

(a) Reversal of opioids overdose.
(b) Treatment of opioid dependence.
(c) Diagnosis of opioid physical dependence.
(d) Naltrexone – an opioid antagonist is used to treat alcohol dependence.

Question 13

The therapeutic uses listed below apply to morphine and most of the other opiates:

Answer 13

 Relief of severe pain (e.g. post-surgical pain and pain experienced by some terminally
ill patients). Analgesia is the major use for the opiates.

 Treatment of diarrhea.

Question 14

Pharmacological Effects of Opioid Agonists

Answer 14

1. Analgesia.
2. Euphoria
3. Sedation.
4. Hypnosis/sleep (narcotic effect).
5. Relief or prevention of cough.
6. Respiratory depression (basis of toxicity) → respiratory arrest.
7. Decreased gastrointestinal motility (constipation).
8. Constriction of the pupils of the eyes (miosis).
9. Nausea, vomiting.
10. Drug dependence. Develops to all opiate analgesics.

Question 15

Morphine and related opioids act on specific receptors on neurons – the

Answer 15

opioid receptors

Question 16

Morphine and related opioids act on specific receptors on neurons – the opioid receptors.
Responses are elicited when these receptors are activated. Naloxone does

Answer 16

not activate these

receptors. However, it occupies and blocks the opioid receptors (an antagonist).

Question 17

Narcotic (Opioid) Drug Dependence -Tolerance:

Answer 17

Loss of effectiveness with repeated administration. Tolerance to most, but not
all, pharmacological effects occurs; the exceptions are constriction of the pupils and the
constipating effect

Question 18

Physical dependence: Develops after repeated administration. A pronounced withdrawal
syndrome can occur and is an indicator of

Answer 18

physical dependence. It is not life threatening.

Question 19

Narcotic (Opioid) Drug Dependence-Physical dependence: A withdrawal syndrome can occur after discontinuing the drug or after administration of Naloxone. The withdrawal syndrome is manifested as:

Answer 19

(a) Restlessness, anxiety, insomnia.
(b) Sweating, fever, chills
(c) Increased respiratory rate
(d) Retching and vomiting
(e) Cramping
(f) Explosive diarrhea

Question 20

The kinds of symptoms, as well as their severity and duration, are determined by

Answer 20

the particular drug, the chronicity and pattern of use, the typical daily dose, concurrent use of
other drugs, the route of administration, and the health of the user.

Question 21

Psychological dependence: (addiction) Pronounced craving and compulsion for narcotic
(opioid) analgesics

Answer 21

can develop

Question 22

The basis for the psychic dependence is the

Answer 22

euphoric action of the

opioids which serves as a very powerful reinforcing factor in the drug-seeking behaviour.

Question 23

Opioid overdose is a medical emergency. Overdose of all opioid drugs can produce profound

Answer 23

respiratory depression which is the cause of death.

Question 24

The euphoria produced by opioid analgesics is the primary reason for their abuse. Factors which
determine abuse of opioids are:

Answer 24

Inherent properties of the compound. How much euphoria and reinforcement does it
produce?
 The size of the dose.
 The route of administration.
 The use of opioids in combination with other drugs.

Question 25

Effects of opioid abuse:

Answer 25

A large number of intravenous drug users suffer deleterious effects of chronic needle
use.
 Abscesses and infections at the site of administration. The major concern is the spread
of disease through contaminated needles (hepatitis and AIDS).
 Lifestyle of the user is often aberrant. They may need to resort to crime or prostitution
to obtain money for drugs. They spend all their money on drugs and leave very little
for nutrition, etc. They do not seek medical help when ill as their use of drugs will be
detected and thus they are often in poor health. They may abandon friends and
family.

Question 26

Treatment of Opioid Dependence

Answer 26

1. Cessation of drug use. Oral methadone replaces the drug of dependence and the dose of
   methadone is slowly reduced over time.
2. Methadone maintenance. This is a method where methadone replaces the drug of
   dependence but the dose is not reduced. The individual substitutes methadone dependence
   for street heroin or other drug dependence.

Question 27

Morphine may be taken

orally in tablet form, smoked, sniffed and

Answer 27

injected

Question 28

Effects of Short-Term Use – Low Doses

CNS: Effects or morphine use include suppression of the sensation of pain and emotional
response to it, euphoria, drowsiness, lethargy, relaxation, difficulty in concentrating, decreased
physical activity in some users, and

Answer 28

increased physical activity in others, mild anxiety or fear, pupillary constriction, blurred vision, impaired night vision, and suppression of cough reflex.

Question 29

Effects of Short-Term Use – Higher Doses

Intensification of morphine’s low-dose effects may occur with administration of higher doses.
Duration of effects also increases with increased dosage. As the dose increases, sensitivity and
emotional response to painful stimuli decrease, probability of sleep increases, ability to
concentrate is increasingly impaired, breathing becomes progressively slower and more shallow,
heart rate gradually slows and

Answer 29

blood pressure decreases.

Question 30

Effects of Long-Term Use morphine-

There does not appear to be marked physiological deterioration or psychological impairment on
long-term use. Adverse effects of long-term use include mood instability, pupillary constriction
(impairs night vision), constipation, reduced libido, menstrual irregularity, and

Answer 30

respiratory impairment.

Question 31

Heroin is

Answer 31

diacetylmorphine. It is produced synthetically from morphine.

Question 32

Heroin was used in the

early 1900’s for medical purposes as an

Answer 32

analgesic.

Question 33

The legitimate medical uses are extremely low. Heroin is more potent than morphine,
but between the two drugs, it is not more

Answer 33

efficacious.

Question 34

It should be noted that heroin is rapidly converted to morphine

Answer 34

in the body.

Question 35

CNS: Effects of heroin use include suppression of the sensation of pain, euphoria, mental
clouding, heightened feelings of well-being, relaxation and drowsiness in some, and in others
talkativeness and

Answer 35

activity

Question 36

Effects of Short-Term Use – heroin Higher doses

As the dose is increased, the magnitude and duration of the response also increase. The response
to painful stimuli is blunted further. The individual becomes less able to concentrate, and wishes
to

Answer 36

sleep

Question 37

Effects of Long-Term Use

As with morphine, heroin, when administered under medical supervision, does not result in
marked physiological or psychological

Answer 37

impairment

Question 38

Tolerance and Dependence

Tolerance develops to heroin with chronic use as it does to all other opiates. Powerful physical
and psychological dependence develops rapidly upon regular

Answer 38

high dose use

Question 39

Potential for Abuse

The dependence liability of heroin is the greatest of the opioids in common use, including

Answer 39

morphine

Question 40

heroin enters the brain quickly after intravenous administration and there is immediate and

Answer 40

intense gratification.

Question 41

The inherent harmfulness in low to moderate doses is

Answer 41

low