🔴MECHANISM OF ACTION

📌ATROPINE

▪Atropine is an antimuscarinic that works through competitive inhibition of postganglionic acetylcholine receptors and direct vagolytic action, which leads to parasympathetic inhibition of the acetylcholine receptors in smooth muscle.
▪The end effect of increased parasympathetic inhibition allows for preexisting sympathetic stimulation to predominate, creating increased cardiac output and other associated antimuscarinic side effects

📌CYCLOPENTOLATE
▪It is a muscarinic antagonist. 
▪It is commonly used as an eye drop during pediatric eye examinations to dilate the eye (mydriatic) and prevent the eye from focusing/accommodating (cycloplegic). ▪Cyclopentolate or atropine can also be administered to reverse muscarinic and central nervous system effects of indirect cholinomimetic  administration.

🔴Mechanism of Protein-Drug Binding
  
         Binding of drugs to proteins is generally reversible which suggests that it generally involves weak chemical bonds such as :
1. Hydrogen bonds
2. Hydrophobic bonds
3. Ionic bonds
4. van der Waal's forces
■ Binding of drugs falls into 2 classes :
▫Binding of drugs to blood components like --
(a) Plasma Proteins
(b) Blood cells
▫Binding of drugs to extracellular tissue proteins,fats, bones, etc.

📌Binding of drugs to Blood Components
🔹Plasma Proteins-DrugBinding:-
 The interaction of drug in the blood compartment is with the plasma proteins which are present in abundant amounts ∈ large variety.
The order of binding of drugs to plasma proteins is :
Albumin > alpha1-Acid Glycoprotein > Lipoproteins > Globulins.
🔹Binding of drugs to Human Serum Albumin :-
The human serum albumin(HSA),having a molecular weight 65,000 is most abundant plasma protein. The HSA can bind several compounds.
4 different sites on HSA for drug binding:-
-Site I :- Warfarin &Azapropazone binding site
-Site II:- Diazepam binding site
-Site III:- Digitoxin binding site
-Site IV:- Tamoxifen binding site
🔹Binding of drugs to alpha1-Acid Glycoprotein :-
It is also known as Orosomucoid it has a molecular weight of 44,000 & a plasma concentration range of 0.04 - 0.1%.
It binds to the number of drugs like Imipramine,Lidocaine, Propranolol &Quinidine,etc.
🔹Binding of drugs to Lipoproteins :-
The drug that binds to lipoproteins does so by dissolving in the lipid core of the protein & its capacity to bind depends upon its lipid  content.
They are classified in the basis of their density into 4 categories:-
1. Chylomicrons(least dense & largest in size).
2. Very low density lipoproteins(VLDL)
3. Low density lipoproteins(LDL)predominant in humans.
4. High density lipoproteins(HDL)most dense& smallest in size.
🔹Binding of drugs to Globulins :-
Different types of plasma globulins are binds they are:-
1. alpha1-globulin:-also called as Transcortin or Corticosteroid Binding Globulin(CBG).It binds to thyroxine & cyanocobalamin.
2. alpha2-globulin:-also called as Ceruloplasmin. It binds to vit.A,D,E,K & cupric ions.
3. beta1-globulin:-also called as Transferrin. It binds to ferrous ions.
4. beta2-globulin:-It binds to carotenoids.
5. gamma-globulin:-It binds specifically you antigens.
🔹Binding of drugs to Blood cells:-
More than 40%of the blood comprises of blood cells of which the major cell component is the RBC.
The RBC comprises of 3 components each of which bind to drugs :-
1. Haemoglobin: Drugs like Phenytoin,  phenobarbital & phenothaizines bind to Hb.
2. Carbonic Anhydrous: Drugs bind to acetazolamide & chlorthalidone.
3. Cell Membrane: Imipramine & chlorpromazine are bind with the RBC membrane.

📌Tissue binding of drugs
--A drug can bind to one or more of the several tissue components.
--Tissue drug binding is important in distribution from 2 points :
1. It increases the apparent volume of distribution of drugs in contrast to plasma protein binding which decreases it.
2. Tigssue drug binding results in localization of a drug at a specific site in the body.
--Drugs that bind to extracellular tissues the order of binding is:
Liver > Kidney > Lung > Muscles

🔴ADR OF ANTICHOLINERGIC DRUGS🔴

📌Dry Mouth
📌Blurred Vision
📌Dry Eyes
📌Constipation
📌Urinary Retention
📌Dizziness(Postural Hypotension)
📌Cognitive Problems(Confusion)
📌Heart Rhythm Disturbance

🔴 Definitions

🔸The autonomic nervous:

The autonomic nervous system is a component of the peripheral nervous system that regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal.


🔸The sympathetic nervous system:

The sympathetic nervous system is part of the autonomic nervous system, an extensive network of neurons that regulate the body’s involuntary processes.


🔸The parasympathetic nervous system:

(PSNS) is a division of the autonomic nervous system (ANS) that controls the activity of the smooth and cardiac muscles and glands.


🔸The somatic nervous system :


(SoNS), also known as the voluntary nervous system, is a part of the peripheral nervous system (PNS). It consists of neurons that are associated with skeletal or striated muscle fibers and influence voluntary movements of the body.


🔸Peripheral nervous system:

The portion of the nervous system that is outside the brain and spinal cord.

🔴MOA OF GANGLIONIC STIMULANTS🔴

➡️Combine with ganglionic nicotinic receptors on the postsynaptic membrane Leads membrane depolarization, Influx of sodium and calcium ions Generation of a fast excitatory - - postsynaptic potential . stimulation of autonomic ganglia and a complex pattern of mixed sympathetic and parasympathetic responses.

🔴MOA OF HEXAMETHONIUM🔴

➡️Hexamethonium is a non-depolarising ganglionic blocker, a nicotinic (nAChR) receptor antagonist that acts in autonomic ganglia by binding mostly in or on the nAChR receptor, and not the acetylcholine binding site itself.

🔴ADR OF GANGLIONIC BLOCKERS🔴

📌Orthostatic Collapse(Fall of arterial blood pressure)
📌Atony of intestine and urinary bladder
📌Constipation
📌Urinary Retention
📌Midrasis
📌Paralysis of accommodation
📌Dry mouth
📌Dysphagy
📌Dysarthria