Respiratory drugs

Question 1

H1 blockers - 1st generation

Answer 1

Diphenhydramine, dimenhydrinate, chlorpheniramine

Mechanism: reversible inhibitors of H1

Use: Allergy, acute uticaria, motion sickness, sleep aid

Toxicity: Sedation, antimuscarinic and anti-alpha-adrenergic effects

Question 2

H1 blockers - 2nd generation

Answer 2

Loratadine, fexofenadine, desloratadine, cetirizine

Mechanism: reversible inhibitors of H1, less CNS entry than 1st gen

Use: Allergy, chronic uticaria

Toxicity: much less sedation than 1st gen

Question 3

Guaifenesin

Answer 3

Expectorant -> thins respiratory secretions but does not suppress cough reflex

Question 4

N-acetylcysteine

Answer 4

mucolytic -> loosens mucous plugs in CF patients by disrupting disulfide bonds

Also antidote for acetaminophen OD

Question 5

Dextromethorphan

Answer 5

Antitussive

Synthetic codeine analog antagonizes NMDA glutamate receptors.

Toxicity: Can cause serotonin syndrome if combined with other serotonergic agents. Mild opioid effect if used in excess and mild abuse potential. Naloxone for OD.

Question 6

Pseudoephedrine, phenylephrine

Answer 6

alpha-adrenergic agonists -> vasoconstrictors

Use: decrease hyperemia, edema, nasal congestion; open obstructed eustachian tubes (Pseudoephedrine used to make methamphetamine)

Toxicity: HTN, CNS stimulation/anxiety with pseudoephedrine

Question 7

Endothelin receptor antagonists

Answer 7

Bosentan

Mechanism: competitively antagonize endothelin-1 receptors -> decreases pulmonary vascular resistance

Use: Idiopathic pulmonary hypertension

Toxicity: hepatotoxic -> monitor LFTs

Question 8

PDE-5 inhibitors

Answer 8

sildenafil

Mechanism: inhibit cGMP PDE5 and prolong NO vasodilatory effect

Uses: Pulm HTN and erectile dysfunciton

Question 9

Prostacyclin analogs

Answer 9

Epoprostenol, iloprost

Prostacyclins (PGI2) with direct vasodilatory effects on pulm and systemic arterial vascular beds. Inhibits platelet aggregation

Uses: Pulm HTN, peripheral vascular disease, Raynaud phenomena

Side effects: flushing, jaw pain

Question 10

Beta2 agonists

Answer 10

albuterol- short acting for acute asthma exacerbation
salmeterol, formoterol - long acting for prophylaxis (used with steroids for asthma and alone for COPD)

Mechanism: beta2 agonists increase AC -> increases cAMP and relaxes bronchial smooth muscle

Toxicity: tremor, arrhythmia

Question 11

Fluticasone, budesonide

Answer 11

corticosteroids, inhibit synthesis of cytokines. Inactivate NF-kB the TF that induces TNF-alpha and other inflammatory agent production

Use: 1st line therapy for chronic asthma

Toxicity: long term use can cause Cushing syndrome

Question 12

Ipratropium

Answer 12

Muscarinic M3 competitive antagonist -> prevents bronchoconstriction

Uses: asthma and COPD; Tiotropium is long acting for COPD

Question 13

Montelukast, zafirlukast

Answer 13

Antileukotrienes- block CysLT1 receptor -> inhibits LTC4, LTD4, LTE4 which cause asthma symptoms

Uses: very good for aspirin-induced asthma

Question 14

Ziluton

Answer 14

Antileukotriene- inhibits 5-lioxygenase pathway -> blocks conversion of arachidonic acid to leukotrienes

Toxicity: hepatotoxic

Question 15

Omalizumb

Answer 15

Anti-IgE monoclonal ab

Binds unbound serum IgE and blocks binding to Fc-epsilon-RL

Uses: allergic asthma resistant to inhaled steroids and long acting beta2 agonists

Question 16

Theophylline

Answer 16

methylxanthine drug

Inhibits phophodiesterase -> bronchodilation

Toxicity: Narrow therapeutic index can cause cardiotoxicity, neurotoxicity, nausea and vomiting. Metabolized by P450 and can block action of adenosine (anti-arrhythmic)

Question 17

Methacholine

Answer 17

M3 agonist –> stimulates bronchoconstriction

Used in bronchial challenge test to diagnose asthma

Question 18

Cromolyn

Answer 18

prevents mast cell degraunlation independent of any stimuli

used for asthma prophylaxis, 2nd line treatment (less effective than glucocorticoids)