pharmacology .. opioid analgesics (nacrotic analgesic)

P H R M A C O L O G Y - NOTE 9 - Opioid Analgesics (Nacrotic analgesic)

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Classes of Opioid Rs

place of Opioid R

partial Agonist (mixed agonist-antagonist)

•Mu

•Kappa

•Delta

•CNS

•Periphral tiissues

•agonist if it is combined with pure agonist.

•antagonist if it is combined with antagonist.

OPIOID ANALGESICS DRUGS

pure Agonist

Morphine

Methagone

Codeine

Pholocodeine

Dextropropoxyphene

Diphenoxylate

Loperamide

Noscapine

Fentanyl

patial Agonist

Nalorphine Pentazocainel

Atagonist

Naloxone



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DRUG PHARMACOKINETIC USES ACTION SIDE EFFECT

Pu

re A

go

nis

ts

Morphine Administration

All taken by orally.

Sustained release formulation.

Morphine is given by I.V. o 75% of it, become inactive

after absorption

Distribution

They are well distributed.

It is lipid soluble.

They cross BBB & placenta.

Metabolism

By microsomal system

The metabolites are active. Heroin (diacetylmorphine) Morphine. Codeine (Methylomorphine) Morphine.

The metabolite are conjugated.

Elimination

Mainly by kidney.

Strong analgesic for chronic pain (cancer).

MI

Add with inhaler GA to produce analgesia.

Manegment for dyspnea.

On CNS. Dysphoria.

Respiratory depression.

Nausea & vomiting.

intra-cranial pressure.

Constipation.

Urinary retention.

Allergy: Itching. Bronchospasm.

Tranceal rigidity(back pain)

ACTION MECHNISM

1 Analgesia

2 Euphoria prominent with pain

Methadone Strong analgesic for chronic pain (cancer). 3 Dysphoria

Meperidine

Strong analgesic for chronic pain (cancer).

Analgesic for labor pain.

Add with inhaler GA to produce analgesia.

4 Resp. sensitivity of RC to CO2

5 Nausea stimulation of CTZ

Vomiting

Codeine Moderate analgesic for chronic pain (cancer)

Cough suppression.

6 Miosis agonize R on III c.n.

7 Antitussive depress the CC

hydrocodeine Moderate analgesic for chronic pain (cancer 8 BP & VD Depress VMC

Pholocodeine Cough suppression On CVS. ( in large iv dose)

Dextropropoxyphen BP depress VMC VD

Noscapine direct VD effect

Diphenoxylate Treatment of diarrhea. release of histamine VD

Loperamide On GIT.

Fentanyl Add with inhaler GA to produce analgesia. 1 Constipa-tion

sphincter tone

s.m. motility

2 intra-billary P

spasm of bile duct

USES COTRA-INDICATION spasm sphincter of oddi Treatment of addication

1) Analgesic for acute & chronic sever pain. a. Acute pain (MI , post-operative) b. Chronic pain (cancer) c. Labor pain

2) Cough suppression. 3) Treatment of diarrhea. 4) Mangment of dyspnea. 5) Analgesic with GA

a. Add with inhaler GA

1) Head injury. Miosis. Resp.

2) Biliary & renal colic(ex Meperidine)

3) Respiratory diseases. (asthma & COPD)

4) Acute abdomen pain. Interfere with proper

diagnosis. 5) Pregnancy & labor (ex Meperidine)

Addict fetus. Neonatal asphyxia.

6) Liver diseases Deficient metabolism

On UT. Clonidine. Control withdrawal symptom. Methadone

1 spasm of ureters

2 Constriction of U sphincter

3 micturation reflex

Tolerance & Dependence.

effect with repeated administration

1 Analgesic Rapid tolerance

2 Resp. Slow tolerance

3 Miosis NOT develop

Acute MORPHINE poisoning 4 constipation

Manifestation: Treatment 5 convulsion

Coma / pin point pupil Hypoventilation & hypoxia Hypotension Hypothermia

1) Artificial respiration. 2) Stomach wash. 3) Repeated I.V.

Naloxone

6 Cross tolerance occur different agonist

Addcation.

Physical D Sudden withdrawal lead to withdrawal syndrome Psycho. D



29

DRUG PHARMACOKINETIC USES ACTION SIDE EFFECT

Pa

rtia

l Ag

on

ists

Pentazocine Agonist on Kappa R.

Partial agonist on Mu R.

Cause weak RC.

Mild dependency.

Mild withdrawal manifestations.

Analgesia. Dysphoria.

Psychomimetic effect. Anxiety. Nightmares. Hallucination.

Withdrawal manifest. with morphine addict.

Buprenorphine Maintainance drug for opioid dependent patient.

Psychomimetic effect. Anxiety. Nightmares. Hallucination.

Withdrawal manifest. with morphine addict

Nalorphine

Pu

re

An

tag

on

ist

Naloxone Acute opiod poisoing Reverse sever respiratory depression.

pharmacology .. opioid analgesics (nacrotic analgesic)

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