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Bronchodilators Notes

Medicine Notes > Respiratory System Notes

This is an extract of our Bronchodilators document, which we sell as part of our Respiratory System Notes collection written by the top tier of Bristol University students.

The following is a more accessble 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:

BRONCHODILATO RS B2adrenoreceptor agonists (BAAs)

Clinical effects/use

Adverse effects

Mechanism of action

Examples

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Activate B2-adrenoreceptor o Increases intracellular cAMP o Activates K+ channel o Activates Na+/K+ ATPase o Reduces Ca2+ dependent coupling of actin and myosin Inhibits cholinergic neurotransmission o Activate muscarinic receptors= smooth muscle contraction

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Unclear Inhibition of cyclic nucleotide phosphodiesterases o Inhibit type IV PDE o Increasing cAMP/cGMP levels- SM relaxation Interaction with G proteins Antagonise adenosine receptors Stimulates CNS/ respiratory centres

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Cholinergic stimulation o Increases SM contraction/
secretion (M3 receptors)

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Xanthine drugs

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Bronchodilatation (most effective) o Increased density of receptors on smooth muscles of trachea to small bronchioles Other effects o Inhibit release of histamine and other inflammatory mediators o Reduce vascular permeability &
mucosal oedema In addition to steroids in patients non-responsive to BAAs In acute severe asthma

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Muscarinic receptor antagonists

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Cysteinyl

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Inhibits mucus secretion Ineffective against late phase asthma Used as adjunct to BAAs/steroids

Generally avoided as given via inhaler Tachycardia and palpitations Pulmonary vasodilatation

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Narrow therapeutic window o 30-100umol/L= Benefit o >120umol/L= Adverse o >200umol/L=
Significant adverse CNS effects o Insomnia, nervousness, seizures CVS effects o Palpitations, tachy, dysrythmia Minimal side effects

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Nausea, sleeplessness, flu,

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Act on 5-lipo-oxygenase pathway

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Short acting: SALBUTAMOL & TERBU o Max. effect in 30 mins o Duration= 3-5 hours o Used "as needed" Long acting: SALMETEROL &
FORMOTEROL o Duration= 8-12 hours o Twice daily o Adjunctive therapy in patients wi chronic asthma Non selective: ISOPRENALINE &
ADRENALINE o Severe asthma

Theophyline o Oral o Metabolises P450 enzymes in liv Drugs induce P450 enzymes red action and vice-versa Aminophyline o Slow IV followed by infusion

Ipratropium Bromide (Atrovent) o Administration: Aerosol intake, n absorbed, max. effect in 30 mins 5h Tiotropium o Longer acting, used in COPD Zileutin

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