Adrenergic drugs

 

🎯 FLOWCHART SUMMARY – ADRENERGIC DRUGS

                     ADRENERGIC SYSTEM

                            │

            ┌───────────────┴────────────────┐

            │                                │

       Receptors                         Adrenergic Drugs

            │                                │

 ┌──────────┼───────────┐             ┌──────┴──────────────────────┐

 │          │           │             │                             │

 α1         α2         β-Receptors   Direct-Acting                Indirect-Acting

 │          │       (β1, β2, β3)     │                             │

 │          │                        │                             │

Vasoconstr •↓NE                     Catecholamines             NE releasers

Mydriasis  •↓Insulin               (Epi, NE, DA, Dobutamine)   (Amphetamine)

Urine Ret •↓SNS outflow            Non-catecholamines          Reuptake blockers

                                     (Salbutamol, PE,          (Cocaine, TCAs)

                                      Clonidine)                MAO inhibitors

            │                                │

            └──────────────────────┬─────────┘

                                   │

                              Mixed Acting

                              (Ephedrine)

                                   │

                                   ▼

                          Physiological Effects

                                   │

      ┌──────────────────────┬───────────────────────────┬─────────────────────┐

      │                      │                           │                     │

 Cardiovascular         Respiratory                 Eye                    Urogenital

 ↑HR (β1)               Bronchodilation (β2)        Mydriasis (α1)         Tocolysis (β2)

 ↑BP (α1)               ↓Allergy med               ↓IOP (α2)              Bladder relaxation (β3)

 Shock mgmt             Asthma, COPD               Glaucoma mgmt          OAB (Mirabegron)

🎨 COLOR-CODED EXAM REVISION TABLE

(Colors shown in text form so you can recreate easily in notes)

🔵 Blue = Classification

🟢 Green = Receptor / MOA

🟡 Yellow = Uses

🔴 Red = ADRs & Cautions

✅ 1. DRUG CLASSIFICATION TABLE

🔵 Class	Drugs	🟢 MOA	🟡 Uses	🔴 ADRs
Direct-acting Catecholamines	Epinephrine, NE, Dopamine, Dobutamine, Isoproterenol	α, β stimulation	Shock, cardiac arrest, HF	↑BP, arrhythmia
Direct-acting Non-catecholamines	Phenylephrine, Salbutamol, Formoterol, Clonidine, Mirabegron	Selective α1, α2, β2, β3	Asthma, nasal congestion, OAB, hypertension	Tremors, rebound HTN (clonidine)
Indirect-acting	Amphetamine, Tyramine, Cocaine, TCAs	↑ NE release / block reuptake	ADHD, depression	Dependence, HTN
Mixed-acting	Ephedrine, Pseudoephedrine	Direct + indirect	Nasal decongestion	HTN, insomnia

✅ 2. RECEPTOR SUMMARY TABLE

Receptor	🟢 Location	🟡 Function	Common Drugs
α1	Blood vessels, eye	↑ BP, mydriasis	Phenylephrine
α2	Presynaptic CNS	↓ NE release	Clonidine, Brimonidine
β1	Heart, kidney	↑HR, ↑renin	Dobutamine
β2	Lungs, uterus	Bronchodilation, tocolysis	Salbutamol, Terbutaline
β3	Adipose, bladder	Lipolysis, bladder relaxation	Mirabegron
D1/D2	Renal & CNS	Renal vasodilation, ↓ prolactin	Dopamine, Bromocriptine

✅ 3. STRUCTURE–ACTIVITY (SAR) SUMMARY TABLE

Structural Feature (🔵)	Effect (🟢)	Example
Catechol OH (3,4)	↑ Potency, not orally active	Epinephrine
Bulky N-substituent	↑ β-selectivity	Isoproterenol
α-Carbon substitution	Prevents MAO metabolism ↑ duration	Ephedrine
Lack of catechol OH	↑ oral absorption	Salbutamol
Imidazoline ring	α2 selectivity	Clonidine

✅ 4. USES & DRUGS TABLE

Disorder (🟡 Yellow)	Preferred Drug
Asthma	Salbutamol, Formoterol
COPD	Indacaterol, Salmeterol
Nasal congestion	Xylometazoline, Oxymetazoline
Shock	NE, Dopamine
Heart failure	Dobutamine
Overactive bladder	Mirabegron
Glaucoma	Brimonidine
ADHD	Methylphenidate

✅ 5. ADRs TABLE

🔴 ADR	Drugs causing it
Tachycardia	β1 agonists
Tremors	β2 agonists
Hypertension	α1 agonists, NE
Rebound hypertension	Clonidine withdrawal
CNS stimulation	Amphetamine
Hyperglycemia	β2 agonists