USMLE Step 2 Review 19 07 Drugs of Choice Asthma 2

USMLE Step 2 Review 19 07 Drugs of Choice Asthma 2

 

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Let’s start our USMLE Review with Drugs of Choice from the Gold Standard USMLE Step 2 Audio Review program.

Play USMLE Audio MP3 19 07 Drugs of Choice Asthma 2 Below

 

Begin 19 07 Drugs of Choice Asthma 2 Transcription

Ok. That’s it for the beta-agonists. Now we’re going to look at other important bronchodilators.

What bronchodilator, delivered IV, has until recently been the drug of choice for emergency treatment of acute asthma?

  • Theophylline.

What is the mechanism of action for Theophylline in bronchodilation?

  • The mechanism of action is unknown.

What family of drug is Theophylline?

  • A xanthene.

Why has Theophylline lost its place as the drug of choice for emergency treatment of acute asthma?

  • It’s simply that inhaled beta-2 adrenergic agonists are more effective bronchodilators.

Theophylline probably should not be added to beta-2 agonist therapy during the acute phase of asthma.

Why?

  • First, studies have not shown additive effectiveness, but studies have shown additive side effects.

However, once the patient has been admitted to the hospital, Theophylline is very useful.

How is Theophylline (PO or IV) used with a hospitalized patient?

  • As part of multi-drug therapy for longer duration of bronchodilation.

And what additional advantages does Theophylline have for treating asthma chronic or during hospitalization?

  • Theophylline also increases the contractility and endurance of the diaphragm and it increases respiratory drive. There are a number of other advantages for Theophylline also, including stimulating the mucociliary action for better clearance of mucus, inhibiting the release of bronchoconstriction mediators, increased myocardial contractility, increased gastric acid secretion, and promotion of diuresis.

Now, there’s 1 more class of drugs which has strong bronchodilator effects, and which has been used quite successfully for acute asthma, although it is not currently recommended as first-line treatment by itself, and what is this class?

  • The anticholinergics.

There is 1 anticholinergic which used to be given aerosolized but has been replaced by a newer drug with much fewer side effects.

What is the older anticholinergic?

  • Atropine.

Let’s briefly review the anticholinergic side effects, keeping in mind that they are usually minimal at low doses. What is the memory image for remembering anticholinergic side effects?

  • Anticholinergic is anti-cool.

Which you think of?

  • Being lost in the desert without water.

And what are the 5 key words?

  • Hot and dry, red, blind, crazy.

I’ll go over these in much more detail in another section. For right now, we’ll just look at 1 of these.

What 6 problems are referred to by the word “dry”?

  • Dry skin, dry mouth, dry nose, dry eyes, retention of urine, and no intestinal secretions or motions.

Ok, what is the newer 4th generation derivative anticholinergic which is an effective bronchodilator and has much fewer side effects?

  • Ipratropium bromide.

And the trade name for Ipratropium?

  • Atrovent.

In what form is Ipratropium/Atrovent available?

  • In a metered dose inhaler.

And when the anticholinergic Ipratropium/Atrovent is used in combination with a beta-2 agonist, such as Metaproterenol or Isoetharine, the effects may be additive due to what difference between the sites of bronchodilation between the 2 classes of drug?

  • Anticholinergics bronchodilate large central airways, while beta-2 agonists bronchodilate smaller airways.

Which bronchodilates the smaller airways?

  • The beta-2 agonists.

And what class and drug bronchodilates the large central airways?

  • The anticholinergic Ipratropium/Atrovent.

Finally, there is 1 more agent, a mineral compound, which is also a bronchodilator and can be helpful as an adjunct to standard therapy. What is it?

  • Magnesium sulfate.

****END OF TRANSCRIPTION****

 

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