Pharmacology Revision

[Saifullah]

I became fed up of studying forensic and now shifted towards studying Pharmacology...

So if you wanna know a bit about pharmacology just follow this thread.

First topic is Cholinergic Agonist

Ok so what is the meaning of cholinergic firstly???

In your body you have something called cholinergic neuron. Normally at these neurons you have synthesis of acetylcholine. The acetylcholine then moves to the ends of the synapse (presynaptic cleft) and then by exocytosis is release into the synapse where it then attaches to receptors at the beginning of the other neuron (post synaptic cleft/neuron). This then causes an action potential to be produced and causes an impulse to be sent down that neuron causing some kind of kind. Those receptors are either called muscarinic receptors and nicotinic receptors. (cholinoceptors). Cholinergic system therefore uses acetylcholine as its neurotransmitter, that is why it is called cholinergic from acetyl-'choline'

Agonist: Agonist is something which increase the activity of the neuron. So increasing the effect.

So Cholinergic Agonists are chemicals/drugs which increase the cholinergic activity of a neuron. As the whole parasympathetic system is based upon stimulation of the cholinergic neuron then sometimes cholinergic agonists are called parasympathomimetics (something mimicking parasympathetic transmission)...

This was a brief introduction of Cholinergic Agonists

[Saifullah]

What is the role of Cholinergic Agonist and what are its functions???

You can figure out what are the actions of a cholinergic agonist if you know what is the parasympathetic functions in the body.

We know that it causes the following functions:
-It contracts the detrusor urinae muscle of bladder wall
-It relaxes the sphincter

These then allow for urination to occur....

-It causes the pupil dilator muscle to relax causing miosis (contraction of pupil)
-Contract ciliary muscle causing short-range focus.

-It dilates arteries to salivary glands and causes increase in salivation

-It increases gastrointestinal motility
-Increases the secretion of gastric glands and gastric acid secretion

-It causes increased sweating

So from this we can figure out the adverse effects of Cholinergic Agonists

1)Diarrhea
2)Diaphoresis (increased sweating)
3)Miosis (pupil contraction)
4)Nausea
5)Urinary urgency

[Saifullah]

Now to understand the classification of Cholinergic agonist i have to explain how the neurotransmitter Acetylcholine is transmitted.

Acetylcholine crosses the synapse and to stop continual transmission there is an enzyme called acetylcholinesterase, this breaks down acetylcholine into acetyl CoA and Choline, therefore stopping the transmission. The indirect Cholinergic Agonist are called anticholinesterases which stop the action of this enzyme which means more transmission of acetylcholine across the synapse. Therefore acting like an agonist indirectly.

So Cholinergic agonist divided into

Direct ACTING-These can bind directly to the receptors
Indirect ACTING-These can stop function on acetylcholinesterase

[Saifullah]

Example of Direct Acting cholinergic agonists

PILOCARPINE
It is used topically in the eye causing miosis and contraction of ciliary muscle.

It is the drug of choice in the emergency lowering of intraocular pressure ofboth narrow angle and wife angle glaucome.

[Saifullah]

Example of Indirect Acting cholinergic agonists

DONEPEZIL, GALANTAMINE, RIVASTIGMINE
These are first line treatment against Alzheimers disease (causes dementia-loss of memory)

EDROPHONIUM AND NEOSTIGMINE
Used in treatment of Myasthenia Gravis (an autoimmune disease where antibodies block acetylcholine at the post-synpatic neuromuscular junction, inhibiting the effect of Acetylcholine)

[Michin Khel]

Saifullah pharmacology is all about memorising names of drugs, their adverse effects and clinical uses. So u cant pick big books like katzung. A short book like Shahnawaz is best for exams though its page memory is little bit weak.

[Saifullah]

Im enjoyin pharmacology, i don't study from katzung but i study from lipincott. Just some of the classification in katzung is good, but u can find that on wikipedia....

I've learnt most of the classification and names of drugs, i just need to learn its actions (thereapeutic uses) and adverse effects abit more

[Michin Khel]

Memorising adverse effects of different drugs is pain in ass, they get mixed with each other.

[Saifullah]

But if u understand most of the adverse effects make sense

Whatever adverse effect of the agonist is, then the antagonist will be opposite of that...so first chapter is easy in that sense

[Michin Khel]

Are there mcqs in 3rd year papers like first and second year?

[Saifullah]

Nope, short questions...

[Michin Khel]

It means you have to read all the details in book especially in pathology whose text book robin is quite heavy

[Laila]

Saifullah, should i take Pharmacology course in my undergrad? What do you think

[Michin Khel]

Saifullah, should i take Pharmacology course in my undergrad? What do you think

Avoid it, it is very difficult subject in terms of retaining the content...

[Saifullah]

Saifullah, should i take Pharmacology course in my undergrad? What do you think

If you wanna do medical later on, pharmacology undergrad will help a lot...