Pharmacology of the ANS

Question 1

Describe the Parasympathetic Nervous System Stimulation. Describe Reversible and Irreversible Agents.

ACh-esterase breaks down ACh,

Stimulation is due to ACh-esterase inhbitors

Answer 1

Stimulated by Acetylcholine-which has a short half life
ACh-esterase inhibitors
Reversible: (N-a-R-P)
1. Neostigmine (Injection Only) and Pyridostigmine(Oral)
2. Alzheimer’s: Increase ACh levels usuing Rivastigmine
3. Mysthenia Gravis: treat with Neostigmine and Pyridostigmine

Irreversible:
Include: Organosphosphates, Pesticides, Malathion, salivation, Bradycardia, Diarrhoea, Sweating, Bronchocontriction, Mucous production

Question 2

Describe the PNS blockers and the agents for this action

Answer 2

MOA- Block action of ACh on muscarinic receptors
Agents include (GHA)
1. Glycopyrrolate (only parenteral, used prior to surgery- can cross BBB)
2. Hyoscine
3. Atropine

Uses
GIT- Irritable bowel syndrome, Diarrhoea, use Hyoscine which has less A/E than Atropine
Surgical
-prevents surgery-induced bradycardia
-Prevents salivation(which could aspirate and cause pneumonia)
Respiratory
Asthma and COPD
-Ipratropium Bromide- Use with Salbutamol in ASTHMA or alone in COPD- metered dose inhaler
-Tiotropium bromide-has longer half-life than Ipratropium, used in COPD
**Glycopyrronium Bromide (Glycopyrrolate)-metred dose inhaler or parenteral before surgery

Question 3

Describe the PNS

Answer 3

Controls the Heart, Respiratory Tract, Urinary Tract

Urinary Tract
Sphincter-relax
Bladder-relax
Penile-Erection

Respiratory tract
Bronchoconstriction ‘
Mocus production

Heart
Decreases Heart Rate

Question 4

PNS blockers

Describe Anticholinergic Side Effects and contraindications of ACh blockers

Answer 4

Anticholinergic side effects
-dry mouth
tachycardia
constipation
bluured visison
urine retention
reducution in sweating

CONTRAINDICATIONS
Tricyclic Antidepressants
H1 Receptor Antagonists

Question 5

Functions of Sympathetic Nervous System

Answer 5

Activated when I’m jogging
Increases Cardia Output, causes peripheral vasocconstriciton and increases blood pressure. decreases blood flow to mesentary and skin. increases blood flow to brain, heart and skeletal muscle.

Question 6

SYMPATHETIC NERVOUS SYSTEM

Describe the activity of beta-1 and beta-2 receptors.

Answer 6

Beta-1 receptors
1.Juxtaglomerular cells: when stimulated, releases renin, activating the RAAS
2.Increased SA node activity
3.Increased conduction at the AV node
4.Myocardium
5.Beta-2 receptors
1. Cause dilation
2. Lower resporatory tract
3. Pregnant Uterus
4. Vascular smooth muscle
5. Liver

Question 7

SYMPATHETIC NERVOUS SYSTEM

Describe the direct and indirect agonists of the SNS

Alpha-1 Agonists

Answer 7

Direct Agonist
Phenylephrine which is an Alpha-1 agonist
Alpha-1 receptor:
1. Upper respiratory
2. Vascular smooth muscle
3. Vasocontrisctor
4. Treats allergies
5. Treats common colds
6. Topical and Oral

Adverse Effects: Increased blood pressure(oral),and rebound congestion of used for more than 3-5 days (topical)

Indirect Agonist
3 agents namely, Ephedrine, Amphetamine and Cocaine
Ephedrine
1. weak release
2. acts on alpha-1
3. Only Oral–“Oral” side effects
4. causes release of noradrenaline in presynaptic terminals

Amphetamine
1. Potent release
2. Release of Noradrenaline, Dopamine and Serotonin

Cocaine
- Reutake Inhibitor
- Afftects NA, Dopamine and Serotonin
- Acts on brain, nasal mucosa, and heart

Question 8

Describe the Agents, Indications, and Adverse Effects of *Short Acting Beta-2 Agonists (SABA)

Answer 8

Agents
1.Salbutamol (Oral, IV or MDI)
2.Fenotorol (MDI)
Indications
1. Reverse Bronchoconstriction in Asthma and COPD (cause bronchodilation)
2. Glucose release
3. Prevent premature Uterine Contraction in Pregnancy
4. Relax vascular smooth muscle in the lung

Adverse Effects
(through beta-1 receptors)
1. Skeletal Muscle Tremor
2. Hyperglycaemia
3. CVS-related:Tachycardia and Palpitations

Question 9

Describe the Adverse Effects, Uses and Agents of Long Acting beta-2 Agonists (LABA)

Answer 9

AGENTS
1. Salmeterol (MDI)
2. Formoterol (MDI)

Same Indications as SABA

Same Adverse Effects as SABA

Question 10

Describe what happens in Anaphylactic Shock and how we treat it.

Answer 10

Anaphylactic Shock
1. Alpha-1: Decrease in BP (intense vasodilation)
2. Beta-1: Drop in cardiac output
3. Beta-2: Bronchoconstricition

This is treated with Adrenaline
Adrenaline with reverse these effects in each receptor respectively.

1. Alpha-1: Vasoconstiction
2. Beta-1: Increase cardia output
3. Beta-2: Bronchodilation

Question 11

Describe Sympathetic Nervous System beta blockers

Describe the AGENTS

Answer 11

1. Propranolol
   Non-selective: beta-1 and beta-2 receptors
2. Atenolol and bisoprolol
   Beta-1 receptors (cardio selective)
3. Carvedilol:
   Beta-1, beta-2 and alpha-1 receptors (very safe)
4. CNS aderse effects
   Vivid dreams, Depression, (This is due to blockage of beta receptors in the brain)