GPAT Study Material related to Pharmacology of Opioid Analgesics

This topic is for quick reference ans also useful for other
Competitive exams like PGCET, GATE etc...

Pharmacology of Opioid Analgesics

History :

- Opium (Greek: juice)



- Theophrastus (300 B.C.)


- Arab traders introduced opium to East Asia


- Opium Wars


- Asian opium smokers brought to U.S.
 
 
Types of Opoid Drugs :
 
- Classified by chemical structure or action at specific receptors



- 20 different alkaloids


- 3 clinical useful (morphine, codiene, papaverine)


- 3 Classes

     Morphine - like drugs


     Meperadine - like drugs


     Methadone - like drugs
 
 
Opioid Drugs - CNS Effects :
 
- Pain centers suppressed (partial agonist / antagonist)- MS



- Suppress medullary cough center (codiene, hydrocodone)


- Decreased gastric motility (paregoric, Lomotil)


- Anaesthetic (Fentanyl)
 
 
Side effects / Adverse effects of Opoid Drugs :
 
CNS- sedation, disorientation, lowered seizure threshold,tremors



CV- Hypotension, palpitations, flushing


Resp - Depression, Asthma aggrivation


GI- N/V, Constipation, biliary spasm


GU- Urinary retention


Skin- Itching, rash, wheal formation
 
 
Toxicity of Opoid Drugs :
 
- Acute Overdose - Narcan



- Tolerance / Dependence (Class II)


- Addiction (Psychological)


- Withdrawal symptoms (Cold Turkey)


                     anxiety, irritability


                    joint pain


                    lacrimation, rhinorrhea, diaphoresis


                    N/V, cramps, diarrhea
 
 
Some of the Opoid Drugs are :
 
- Morphine Sulfate (Astramorph, Roxanol, MS Contin)



- Meperidine HCl (Demerol, Pethidine)


- Methadone HCl (Dolophine)


- Propoxyphene HCl/ Napsylate (Darvon, Dolene)


- Codiene


- Fentanyl (Duragesic, Sublimaze)