Pharmacology

• 1. alpha-Methyltyrosine
• 2. alpha-Methyldopa
• 3. Reserpine

Mechanism: Inhibits tyrosine hydroxylase

Major Indications: Pheochromocytoma

Adverse Effects: Drowsiness, Depression

Mechanism: Prodrug, Converted to alpha-MethylNE (replaces NE)

Major Indications: HTN

Adverse Effects: Sedation, xerostomia

Other: alpha-MeNE is an a₂ agonist (HTN effects)

Mechanism: blocks VMAT-2 (depletion of NE in synaptic vesicles)

Major Indications: HTN

Adverse Effects: extreme sedation, severe depression, diarrhea, nasal congestion

Other: seldom used

• Indirect Sympathomimetics
• 1. Amphetamine
• 2. Ephedrine (Sudafed)

Mechanism: uptake by NET and then by VMAT, displacing NE into the junctional space

Major Indications: ADHD, narcolepsy

Adverse Effects: drug abuse, increase BP HR and cardiac arrythmias, insomnia, headaches, nervousness

Mechanism: uptake by NET and then by VMAT, displacing NE into the junctional space

Major Indications: Hypotension, nasal congestion (pseudoephedrine)

Adverse Effects: increase BP and HR, insomnia, nervousness

Other: weak agonist effects an Beta receptors

• 1. Tricyclic anti-depressants (Amitriptyline)
• 2. Cocaine

Mechanism: inhibit NET (NE stays in NEJ)

Major Indications: depression, neuropathic pain, migraine prophylaxis

• Adverse Effects:
• -mAChR antagonistic side effects (dry mouth, urinary retention, confusion)
• -alpha₁ antagonist effects (postural hypotension)
• -H₁ antagonist effects: sedation, increase weight gain
• -Cardiac arrythmias

Other: low therapeutic index (overdose)

Mechanism: Inhibit NET (NE in NEJ)

Indications: drug of abuse

Adverse effects: increase BP, HR and cardiac arrhythmias

1. MAO inhibitors

2. COMT inhibitors

Mechanism: inhibit MAO (NE metabolism)

Indications: depression, Parkinson's

Adverse Effects: HTN crisis when ingest tyramine-containing foods

Mechanism: inhibit COMT (NE metabolism)

Indications: Parkinson's

• 1. NE
• 2. Epi

Mechanism: stimulates a₁, a₂ and b₁ receptors

Indications: Severe hypotension, shock (to increase BP)

Mechanism: stimulates a₁, a₂, b₁ and b₂ receptors

Indications: acute anaphylactic reactions, cardiac arrest (maintain BP), severe hypotension, shock, local anesthesia (increased duration of action by decreasing blood flow to area)

Other: given at relatively high dose so a receptor vasoconstriction predominates of b₂ receptor vasodilation

Phenylephrine

Mechanism: stimulate a₁ receptors

Indications: Nasal congestion, opthamalogical exam (mydriasis)

Adverse Effects: increase BP

Other: use with caution in Pt with HTN and BPH

Clonidine

Mechanism: stimulates a₂ receptors

Indications: HTN

Adverse Effects: sedation, xerostomia

Other: anti-HTN effects primarily due to stimulation of a₂ receptors on medulla oblongota (decreases sympathetic tone)

Phentolamine

Mechansim: blocks a receptors

Indications: pheochromocytoma

Adverse Effects: postural hypotension with reflex tachycardia

• 1. Prazosin
• 2. Tamsulosin

'-osins'

Mechanism: blocks a1 receptors

Indications: HTN, BPH

Adverse Effects: Postural hypotension, with reflex tachycardia

Mechanism: blocks a₁ receptors

Indications: BPH

Adverse Effects: postural hypotension with reflex tachycardia

Other: causes less hypotension

Isoproterenol

Mechanism: stimulates b receptors

Indications: extreme bradycardia and AV block

Side Effects: tachycardia, cardiac arrhythmias, angina pectoris

Other: used in emergency situations

Dobutamine

Mechanism: stimulates b₁ receptors

Indications: Cardiogenic shock

Other: increases ionotropic state more than HR

Albuterol

Mechanism: Stimulates b₂ receptors

Indications: Asthma, COPD

Adverse Effects: tremor, anxiety, apprehension, cardiac stimulation (not 100% selective)

Other: administer by inhalation to reduce side effects

Propranolol

Mechanism: block b receptors

Indications: HTN, angina pectoris, MI, CHF, cardiac arrhythmias, glaucoma, essential tremor, performance anxiety, migraine prophylaxis

Side Effects: CH, bradycardia, AV block, bronchoconstriction, fatigue, sleep disturbance, depression, impair peripheral circulation (b2 receptors), sexual dysfunction in males, increased risk of hypoglycemic episodes in diabetes, increase risk of sudden death and exacerbation of angina pectoris with discontinued use

• 1. Metoprolol
• 2. Atenolol

(A-N -olols)

Mechansim: blocks b₁ receptors

Indications: HTN, angina pectoris, MI, CHF, cardiac arrhythmias, glaucoma, essential tremor, performance anxiety, migraine prophylaxis

Side Effects: CH, bradycardia, AV block, bronchoconstriction, fatigue, sleep disturbance, depression, impair peripheral circulation (b2 receptors), sexual dysfunction in males, increased risk of hypoglycemic episodes in diabetes, increase risk of sudden death and exacerbation of angina pectoris with discontinued use

Mechanism: block b receptors with additional CV actions (vasodilation)

Indications: HTN, angina pectoris, MI, CHF, cardiac arrhythmias, glaucoma, essential tremor, performance anxiety, migraine prophylaxis

Side Effects: CH, bradycardia, AV block, bronchoconstriction, fatigue, sleep disturbance, depression, impair peripheral circulation (b2 receptors), sexual dysfunction in males, increased risk of hypoglycemic episodes in diabetes, increase risk of sudden death and exacerbation of angina pectoris with discontinued use