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Medicine Notes Respiratory System Notes

Bronchodilators Notes

Updated Bronchodilators Notes

Respiratory System Notes

Respiratory System

Approximately 49 pages

These notes are on the Respiratory System of the human body. helped me achieve a mark of 68% in my respiratory exam, which is the equivalent of a 2:1. The notes are based on a series of lectures on the subject. They are very clearly laid out and easy to follow. They cut out unnecessary information on the topic, making the notes very concise, and fast to get through. Anyone studying medicine, or any other subject requiring knowledge of the Respiratory system (e.g. physiology or anatomy), would ben...

The following is a more accessible plain text extract of the PDF sample above, taken from our Respiratory System Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Clinical effects/use Adverse effects Mechanism of action Examples
BRONCHODILATORS
B2- adrenoreceptor agonists (BAAs)
  • Bronchodilatation (most effective)

  • Increased density of receptors on smooth muscles of trachea to small bronchioles

  • Other effects

  • Inhibit release of histamine and other inflammatory mediators

  • Reduce vascular permeability & mucosal oedema

  • Generally avoided as given via inhaler

  • Tachycardia and palpitations

  • Pulmonary vasodilatation

  • Activate B2-adrenoreceptor

  • Increases intracellular cAMP

  • Activates K+ channel

  • Activates Na+/K+ ATPase

  • Reduces Ca2+ dependent coupling of actin and myosin

  • Inhibits cholinergic neurotransmission

  • Activate muscarinic receptors= smooth muscle contraction

  • Short acting: SALBUTAMOL & TERBUTALINE

  • Max. effect in 30 mins

  • Duration= 3-5 hours

  • Used “as needed”

  • Long acting: SALMETEROL & FORMOTEROL

  • Duration= 8-12 hours

  • Twice daily

  • Adjunctive therapy in patients with chronic asthma

  • Non selective: ISOPRENALINE & ADRENALINE

  • Severe asthma

Xanthine drugs
  • In addition to steroids in patients non-responsive to BAAs

  • In acute severe asthma

  • Narrow therapeutic window

  • 30-100µmol/L= Benefit

  • >120µmol/L= Adverse

  • >200µmol/L= Significant adverse

  • CNS effects

  • Insomnia, nervousness, seizures

  • CVS effects

  • Palpitations, tachy, dysrythmia

  • Unclear

  • Inhibition of cyclic nucleotide phosphodiesterases

  • Inhibit type IV PDE

  • Increasing cAMP/cGMP levels- SM relaxation

  • Interaction with G proteins

  • Antagonise adenosine receptors

  • Stimulates CNS/ respiratory centres

  • Theophyline

  • Oral

  • Metabolises P450 enzymes in liver. Drugs induce P450 enzymes reduce action and vice-versa

  • Aminophyline

  • Slow IV followed by infusion

Muscarinic receptor antagonists
  • Inhibits mucus secretion

  • Ineffective against late phase asthma

  • Used as adjunct to BAAs/steroids

  • Minimal side effects

  • Cholinergic stimulation

  • Increases SM contraction/ secretion (M3 receptors)

  • Ipratropium Bromide (Atrovent)

  • Administration: Aerosol intake, not well absorbed, max. effect in 30 mins lasts 3-5h

  • Tiotropium

  • Longer acting, used in COPD

Cysteinyl
  • Nausea, sleeplessness, flu, cough

  • Avoid if have liver damage

  • GI upsets, headaches

  • Act on 5-lipo-oxygenase pathway (mast cells)

  • Zileutin

  • Inhibits 5-lipoxxygenase. Increases liver

  • Montelukast

  • Blocks CysLT1. Relax airways

ANTI-INFLAMMATORIES
Glucocorticoids
  • Main one used in asthma

  • Prevent progression of chronic/improve function

  • Inhaled glucocorticoids

  • First line for all patients with persistent symptoms

  • Most preventive for adults and older children

Systemic glucocorticoids

  • Weak anti-inflammatory, short duration

  • Reduce intermediate/late phase asthmatic response

  • Inhaled

  • Dysphonia

  • Oropharyngeal candidiasis

  • Cough and throat irritation

  • “Cushing’s syndrome” symptoms (Fluticasone)

  • Inhaled

  • Reduce IL-3 synthesis (less mast...

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