pharma sheet # 22 - Suhaib Attiyeh

By the name of Allah

Date of lec: 7/11/2010
Lec #: 22
This lecture was the first after the exam & the doctor discussed some of the questions with the students.
Note: you should read the slides with the sheet.
We talked in the last lectures about analgesics & we calcified them to opioids & non-opioids (non-steroidal analgesics).
Now we will talk about the opioids:
The scheme in the first slide represents the sequence of giving an analgesic in case of postoperative pain:
First: we give acetaminophen (panadol, parasetamol, talenol or any of these drugs)
If two tablets are insufficient to relieve pain (i.e. moderate to severe pain) we may give
Either: NSAID (non-steroidal anti-inflammatory drugs) if it’s not contraindicated
Or: if NSAID are contraindicated as in the case of renal problems we add opioids (codeine or oxacodon) to the acetaminophen.
Opioids (known as m5drat (forbidden drugs) in Arabic)
*have a very high abuse.
*act by binding to specific opioid receptors.
*their effect resembles that of natural endogenous substances known as enkephalin & endorphins.
*enkephalins & endorphins inhibit pain sensation by binding to postsynaptic nerve ending of different opioid receptors (µ -the most important- , δ, σ, ɣ & another fifth receptor).

*mechanism of action:
1- Decrease excitability by increase permeability of K+ ions (increase threshold).
2- Decrease release of neurotransmitter by decrease Ca++ influx.
The end result is: there’s no action potential toward pain sensation (analgesic activity).
*they also have sedative effect (which isn’t found in NSAID) so we give them before surgery
* So activation of opioid receptors by opioid (codeine or morphine) inhibit pain sensation but if we give the patient overdose or as we see in cases of morphine or heroine (as forbidden drug) over dose, we need to give the patient a blocker that antagonist the action of opioid which is Naloxone (pharmacological antagonism).
*uses of opioids:
1- To alleviate moderate to severe pain on µ receptors (but we tend to use the opioid as the last choice).
2- Cough center suppression on ɣ & µ (as antitussive like drug called coldex which contain codeine as an opioid).
3- Treatment of diarrhea (decrease GI muscles contractibility----cause constipation as in cancer patient).
4- Balanced anesthesia (we may use morphine to decrease level of anesthesia because anesthetics are dangerous & cause deaths)
*effects of opioids:
1- Damping (inhibitor) effect:
a) In analgesia --- inhibition of pain & mood alertness (being awake-m9797- )
b) Antitussive (cough center inhibition)
2- Stimulant (activator) effect:
a) In analgesia --- activation of many centers of antinociceptive system that inhibit pain sensation
b) Ant diarrheal (activation of GI spastic constipation-GI smooth muscles contraction-)
*SO analgesic effect of opioids is done by both inhibition of pain & mood alertness and activation of antinociceptive system.

* Side effects of opioids:
1- It affects the respiratory center & inhibit it which is a big problem (this is the main side effect).
- All deaths of heroine over dose are due to the suppression of respiratory center by inhibiting CO2 level sensation in the body (the body can no longer sense the increase in CO2 in the blood) and that occurs in cases of high doses.
2- Cause constipation so we don’t use opioids any more to treat diarrhea.
*the doctor started to talk about Morphine:
• Morphine is a very nice drug and some says that it’s one of the blessings of the GOD.
• Patients treated with morphine are still aware of the presence of pain, but sensation is not unpleasant so we never can produce something like it.
• It also causes euphoria.


Happy Eid w kol 3am w2nto b2lf 5air
Done by: Suhaib attieh
Lecture #: 22