14 - OPIOID DRUGS

Question 1

Full agonists

Answer 1

Codeine (methylmorphine)

Heroine

Question 2

CODEINE (METHYLMORPHINE)

Answer 2

Less analgesic activity than morphine. Does not generate dependence. P.O.
- Indications: antitussive and analgesic for moderate pain – administration alone or combined
with NSAID. Induces constipation.

Question 3

HEROINE

Answer 3

Synthetic derivative of morphine, 2-10 times more potent. More liposoluble and rapidly crosses BBB producing intense and rapid effects. Short half life (2h), creates dependence. Illegal.

Question 4

PURE AGONISTS

Answer 4

PETIDINE (MEPERIDINE)
FENTANYL
SUFENTANYL

Question 5

PETIDINE (MEPERIDINE)

Answer 5

PURE AGONIST (

Similar to morphine but 10 times less potent. Parenteral and
oral administration. Used as alternative to morphine. Anticholinergic properties. Lacks
antitussive activity and induces less constipation. Its conversion to norpetidine provokes
cardiovascular and neuronal stimulation (muscle tremor, arrhythmia, hallucinations, delirium
with disorientation).

Question 6

FENTANYL

Answer 6

50-150 times more potent than morphine. Rapid effects and great potency.

Low toxicity. Half life: 30-45 min. High liposolubility. Use: Induction of anaesthesia and
analgesia. Administration: intravenous but also epidural, oral transmucose and transdermic.

Question 7

SUFENTANYL

Answer 7

400-1000 times more potent than morphine and 10 times than fentanyl.
Use: anaesthetic or analgesic through special routes (epidural and nasal).

Question 8

METHADONE

Answer 8

Slightly more potent than morphine. P.o. Half life: 18h – it can increase to
47h upon chronic use. Antagonist of NMDA (N-methyl-D-aspartate) glutamate receptor. Risk
of accumulation and toxicity. Use: dishabituation of drug addicts.

Question 9

TRAMADOL

Answer 9

Similar to codeine. Its analgesic action is only partially antagonized by naloxone - implication of other mechanisms such as upregulation of the serotonergic and noradrenergic spinal and brain stem pathways (inhibits re-uptake of NA and SER). Lower
activity to opioid R.

Question 10

PARTIAL AGONISTS

Answer 10

BUPRENORPHINE

Question 11

BUPRENORPHINE

Answer 11

25-30 times more potent than morphine. Analgesic by parenteral, intrathecal, sublingual and transdermal (transdermal patch) administration. Dependence
and tolerance. Produces respiratory depression, myosis, less constipation and does not
induce cardiovascular effects. Used for dehabituation.

Question 12

MIXED AGONISTS / ANTAGONISTS

Answer 12

Affinity for κ receptors but very little or none for µ resulting in less respiratory depression
and hypertonia of the GI tract but stronger psychotomimetic effects: fatigue, somnolence,
dizziness, vertigo, nervousness (effects due to κ stimulation).

PENTAZOCINE

Question 13

PENTAZOCINE

Answer 13

Analgesic p.o. (low analgesia) and parenterally. Used less due to its psychotomimetic effects, tachycardia and hypertension- it can also induce agranulocytosis.
Induces dependence

Question 14

ANTAGONISTS

Answer 14

NALOXONE

NALTREXONE

Question 15

NALOXONE

Answer 15

Used to combat morphine intoxication. Parenteral route. Half life: 1-1.5h.

INTOXICATION

Question 16

NALTREXONE

Answer 16

Used in dishabituation of heroin addicts. p.o. Half life: 10h. 2 times more potent than naloxone.