Narcotic analgesics

أهم النقاط في محاضره ال Morphine ✅Mechanism of action:

1- Presynaptic level : opioid couple with G inhibitory protein --> ↓adenyle cyclase enzyme →↓ cAMP → ↓ voltage gated calcium channel → decrease neurotransmitters release

2- postsynaptic level: ↑ opening of k channel → k efflux → hyperpolarization

✅ Action:

1- CNS : analgesic by :1- spinal analgisia

2- supra spinal analgisia

3- ↓ NE release → ↓ pain sensory and emotional

2- CVS : Bradycardia and hypotension without reflex tachycardia Why ?: because morphine has stimulatory effect on vagal nucleus

3- respiratory depression

4- on CTZ : nuasia and vomiting

5- antitussive ( inhibition for cough center)

6- smooth muscle: spasmognic effect on muscle of GIT

7- ↑ ICP

✅ Pharmacokinetics (مهمة جدا)Bioavailability : 20% so it's administrated SC or IM but not IV because it cause severe hypotension except in One case : in neurogenic shock diluted with saline why ??? to relieve severe pain and decrease sympathetic overactivity, since the vessels are already maximally dilated.

Morphine is metabolized by conjunction with glucuronic acid which converte to more active

✅ Therapeutic uses

1- severe pain

2- pulmonary edema

3- MI

4- colic pain combined with anticholinergic drugs except with billary colic

5- antitussive

✅ Adverse effects:

M: miosis ( pin point pupils)

O: out of sedation

R: respiratory depression

P: physical dependence

H: hypotension

I: infrequency ( urine retention)

N: nausea and vomiting

✅ Contraindications

1- elderly people: due to ↓ glucurination in liver and they have enlarged prostate so morphine cause urine retention

2- infant: as elderly except enlarged prostate

3- billary colic: because it cause severe contraction at the sphincter of Oddi

4- pregnant woman

5- head injury: because morphine ↑ ICP by CO2 retention which vasodilation in cerebral vessels

6- bronchial asthma