Opioid Analgesics

Question 1

What are opioids?

Answer 1

Natural and semi-synthetic compounds derived from opium

And fully synthetic compounds

Which mimic the pharmacological actions of morphine

Question 2

What are the types of opioid receptors?

Answer 2

Mu- spinal and supraspinal

Kappa - spinal ( no dependence)

Delta - peripheral (endogenous, no dependence)

Sigma - psychotic, no analgesia ( not inhibited by naloxone)

Question 3

What are the endogenous opioids?

Answer 3

Dynorphins

Enkephalins

Endorphins

Endomorphins

Nociceptin

Question 4

What is the mechanism of action of opioids?

Answer 4

Ligands bund to GPCR

Inhibit cAMP

K+ efflux increased
Ca2+ influx decreased

Neurotransmission inhibited

Question 5

What are the types of opioids?

Answer 5

By origin
By potency

Natural opium alkaloids
Morphine
Codeine

Semisynthetic
Diacetylmorphine(heroin), pholcodeine

Synthetic
Pethidine,
Fentanyl 
Methadone
Tramadol 

Strong
Fentanyl (super strong immediate short action)
Morphine
Heroin
Methadone (PO for dependence therapy)

Moderate
Codeine for cough suppression

Question 6

What is drug tolerance?

Answer 6

Diminished responsiveness to a drug action

Due to repeated or prolonged time of administration

Specially seen in opioids, decreased actions (except miosis and constipation)

Question 7

What is dependence?

Answer 7

Medical conditions which characterize

The compulsive use of opioids

In spite of consequences of continued use

And the withdrawal syndromes which occur when use is stopped

Question 8

What are the signs of opioid withdrawal?

Answer 8

Yawning
Lacrimation
Rhinorrhea 
Salivation
Anxiety
Sweating
Cramps
Spasms
Pain

Question 9

What are the types of opioid receptor antagonists?

Answer 9

Partial antagonists
To precipitate a withdrawal in addicts
Pentazocine
Buprenorphine

Full antagonists 
To reverse acute poisoning
To precipitate a withdrawal in addicts
Naloxone
Naltrexone

Question 10

What are the signs of acute opioid poisoning?

Answer 10

Respiratory depression (Cheyne-Stokes)
Coma
Euphoria
Sedation
Tranquilization
Hypotension
Constipation
Miosis
Hypothermia
No secretions
Warm flushed skin

Question 11

How do you treat acute opioid poisoning?

Answer 11

Naloxone IV 0.4 to 1.2 mg

Stomach lavage with permanganate 0.1%
and 0.5% tannin

Activated charcoal 30g

Diuretics

Ventilation with 95% O2

Question 12

What are the uses of pethidine?

Answer 12

Alternative for morphine

For acute pulmonary edema

For pre anesthetic analgesia

Not for cough and diarrhea

Question 13

What are the pharmacokinetics of morphine?

Answer 13

Low oral bioavailability due to significant first pass metabolism

Sub cut administration

Enter all tissues

6 hours duration

Question 14

What are the side effects of morphine?

Answer 14

Respiratory depression 
Vomiting
Bradycardia 
Hypotension
Sphincter spasm (constipation)
Retention of urine

Question 15

What are the contraindications for morphine?

Answer 15

Acute respiratory depression

Acute asthma

Paralytic ileus

Head injury

Raised intracranial pressure

Question 16

What are the important points on tramadol?

Answer 16

Centrally acting PO opioid

On mu receptor
Enhances serotonin release
Inhibit reuptake of noradrenaline

20% first pass metabolism

Renal excretion

Hepatic metabolism into more active metabolite

Less side effects, more nausea and dizziness

Caution in epilepsy