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Cholinergic Drugs - Coggle Diagram

- - - - R-(−)-enantiomer
        
        -approximately 20-fold less potent
        -not hydrolyzed by AChE and even acts as a weak competitive inhibitor of the enzyme.
      - Racemic R,S
        
        -produces a longer duration of action than acetylcholine.
      - S (+) enantiomer
        
        -equipotent with ACh
        -AchE hydrolyes it much slower than Ach due to steric hindrance by β-methyl gp.
    - - -Prolonged effect (steric and carbamate).
        -Orally active potent muscarinic agonist
        -The S (+) enantiomer exhibit much greater binding to muscarinic receptors than the R(-) enantiomer.
    - - -more resistant toward acid-, base-, or enzyme (AChE)-catalyzed hydrolysis than acetylcholine
        -Exhibits weak anticholinesterase activity.
  - - - Neostigmine Bromide
        
        The distance between the carbamate ester and the quaternary ammonium group is approximately the same as that found in acetylcholine
        
        The advantage of Neostigmine over the others is that:
        
        1.It is tertiary carbamate, so it is more stable to hydrolysis due to increased inductive e-donating effect into carbonyl from extra N methyl
        2.It cannot cross the blood-brain barrier due to the positive charged quaternary ammonium center and thus lacks the central activity.
        3.Longer duration of action.
        4.Orally active.
      - Edrophonium chloride
        
        -It is structurally related to neostigmine
        -Because it is a phenol rather than a carbamate ester of
        phenol, it does not carbamylate
        -It does, however, inhibit AChE in a reversible manner, and also exhibits a direct cholinomimetic effect at skeletal muscle
        -It is rapidly absorbed.
        -It is less potent.
        -It has short duration of action.
      - Donepezil (Non-Classical)
        
        Highly lipophilic
    - - Echothiophate iodide
      - Malathion
        
        It is rapidly bioactivated by desulfurization by microsomal oxidationin insects to afford the corresponding oxoderivatives which are very potent -There are no metabolic pathways in mammals that can convert the phosphorous/sulfur double bond to phosphorous/oxygen double bond
- - - - Pirenzepine
    - - Solanaceous alkaloids and
        synthetic analogs
        
        Atropine sulphate
        
        Racemic mixture of D&L-hyoscyamine
        
        Scopolamine HBr (Hyoscine HBr)
        
        It is scopine ester of (-) tropic acid
        
        Ipratropium bromide
        
        • It is synthetic analog.
        • Quaternary amine, localized in the lung.
      - Amino Alcohol Esters having general
        formula R1COOR2
        
        Trospium chloride
      - Aminoether having general structure
        R1OR2
        
        Benztropine
  - - - Are not therapeutically useful since they can notdistinguish between the ganglia of sympathetic andparasympathetic nervous system consequently, theyhave many side effects.
    - - Non-depolarizing blocking agents(competitive)
        
        Curare
        
        d-Tubocurarine
        
        Pancuronium bromide
        
        Reversed by
        
        anticholinesterases such as neostigmine
      - Depolarizing blocking agents (Bis–quaternary ammonium compounds)
        
        Decamethonium Bromide
        
        has an extended conformation, and is the prototype
        
        binds too strongly to the receptor and
        as a result, patient recovery from the effects is delayed
        
        To circumvent this problem, Succinylcholine was introduced as a soft drug
        analog (short duration).
        
        Succinylcholine ChlorideSuxamethonium Chloride
        
        is a related compound that possesses the same intraatomic N+ distance although not all atoms between the charged centers are
        carbon.
      - -quaternary ammonium compounds thus can’t pass BBB.
        -They act at the periphery.