Respiratory smooth muscle relaxants

Question 1

What are two examples of respiratory smooth muscle relaxants?

Answer 1

Aminophylline

Theophylline

Question 2

How do aminophylline and theophylline work?

Answer 2

Competitive non-selective phosphodiesterase inhibition –> increases IC cAMP, activates PKA, and inhibits TNF-a leukotriene synthesis –> reduces inflammation and innate immunity

Question 3

What is the net effect of aminophylline?

Answer 3

Bronchodilation
Relieves SOB, wheezing, dyspnea
Improves pulmonary function measured by flow rates and vital capacity

Question 4

What is the net effect of theophylline?

Answer 4

Bronchodilation

Question 5

What are some toxicities to aminophylline and theophylline?

Answer 5

Theophylline toxicity (cardiotox, neurotox)
GI disturbances
CNS stimulation
Tachycardia
Nervousness
Seizures

Question 6

What decreases clearance of aminophylline and theophylline?

Answer 6

CHF
Hepatic dx
ESRD
Elderly
Neonates
Pregnancy

Question 7

What increases clearance of aminophylline and theophylline?

Answer 7

Smoking

Metabolized by P450

Question 8

Patients with which disorders should NOT be given aminophylline or theophylline?

Answer 8

Seizures

GI dx

Question 9

Which respiratory smooth muscle relaxant is less potent and shorter acting?

Answer 9

Aminophylline