BASIC - RESPIRATORY Flashcards
Names of short/long-acting beta-2-agonists?
- Short-Acting
o Salbutamol, Terbutaline - Long-Acting
o Salmeterol, formoterol
Indications of beta-2-agonists?
- Asthma – short acting as step 1, long-acting as step 3 (must be given with inhaled corticosteroids)
- Hyperkalaemia – nebulised salbutamol (in addition to insulin, glucose, calcium gluconate) in emergency treatment
Mechanisms of beta-2-agonists?
- Beta2-receptors found in smooth muscle of bronchi, GI tract, uterus, blood vessels
- Stimulation of GPCR leads to smooth muscle relaxation – improves airflow
- Stimulate Na/K/ATPase pump causing K+ to move into cells – treat hyperkalaemia in addition to insulin
Side effects of beta-2-agonists?
- ‘Fight-or-flight’ effects
o Tachycardia, palpitations, anxiety, tremor - Gluconeogenesis, may increase serum glucose
- High doses
o Serum lactate levels increased - Long-acting
o Muscle cramps
Interactions of beta-2-agonists?
- Beta-blockers reduce effectiveness
- Hypokalaemia
o Concomitant use with theophylline, corticosteroids
What must long-acting beta-agonist be prescribed with?
- Long-acting only prescribed in asthma with inhaled corticosteroid
o As associated with increased asthma deaths
Cautions of beta-2-agonists?
o CVD – tachycardia promote angina, arrhythmias
o Hypokalaemia
o Diabetes
Prescription of beta-2-agonists?
- PRN prescription
o Use 2 puffs every 4 hours, up to 10 if needed
o If more, then hospital - Can be administered aerosol (MDI), dry powder, nebulised, in combination with steroid (Symbicort, Seretide)
- Spacer provided to improve airway deposition and treatment efficacy
Monitoring asthma?
- Monitored via peak expiratory flow rate (PEFR)
Names of antimuscarinics?
Ipratropium, tiotropium, glycopyrronium
Indications of antimuscarinics?
- Acute exacerbation (short-acting)
- Added in step 4 of chronic asthma (long-acting)
Mechanism of antimuscarinics?
- Bind to muscarinic receptor, competitive inhibitor of acetylcholine
- Stimulation of muscarinic receptor causes ‘rest and digest’ effects
- Blockage has opposite effects:
o Reduced smooth muscle tone
o Reduced secretions
o Relaxation of pupillary constrictor and ciliary muscles – pupil dilatation and preventing accommodation – blurred vision
Side effects of antimuscarinics?
- Little systemic absorption
- Blurred vision, urinary retention, constipation, dry mouth
Cautions of antimuscarinics?
o Angle-closure glaucoma
o Arrhythmias
Contraindications of antimuscarinics?
o Hypersensitivity to atropine or derivatives
Prescription of antimuscarinics?
- Short-acting used QDS or PRN
- In acute asthma
o 0.25mg in 4mL saline
o Every 20-30 mins for 1st 2 hours then every 8 hours if needed
Indications of theophylline?
- Chronic asthma
- Severe acute asthma
- Reversible airway obstruction (COPD)
Mechanism of theophylline?
- Xanthine derivative
- Competitively inhibits PDE 3 and 4 and also binds to adenosine A2B receptor
- Smooth muscle relaxation (bronchodilation) and suppression of airway response to histamine, methacholine, adenosine, allergens
Side effects of theophylline?
- Narrow therapeutic window
- GI upset – nausea, diarrhoea
- Tachycardia, Arrhythmias
- Headaches, insomnia, dizziness
- Hypokalaemia
- Overdose (>10mg/litre)
o Vomiting, agitation, dilated pupils, sinus tachycardia, convulsions
Cautions of theophylline?
- Arrhythmias
- Elderly
- Epilepsy
- Risk of hypokalaemia
Interactions of theophylline?
- Affected by CYP450 enzymes
- Reduce dose in hepatic impairment
Advice on taking theophylline?
- Avoid alcohol, excessive caffeine
- Take with food, swallow whole
Monitoring of theophylline?
o Plasma theophylline concentrations measured 5 days after oral treatment and >3 days after dose changes
Names of inhaled corticosteroids?
Beclomethasone (Clenil Modulite 50mcg lower-potency, Clenil 200mcg), budesonide, fluticasone
Indications of inhaled corticosteroids?
Step 2 of therapy in chronic asthma – not controlled by short-acting B2 agonists
Chronic obstructive pulmonary disease (COPD) – usually with LABA/LAMA
Mechanism of inhaled corticosteroids?
- Pass through plasma membrane and activate receptor which:
o Upregulation of anti-inflammatory proteins
o Downregulates pro-inflammatory interleukins, cytokines, chemokines - Effects
o Reduces mucosal inflammation
o Widens the airways
o Reduces mucus secretion
Side effects of inhaled corticosteroids?
- Occur locally in the airway
o Oral candidiasis
o Hoarse Voice - Few systemic effects unless at very high dose which may cause adrenal suppression, growth retardation and osteoporosis
Doses of inhaled corticosteroids?
- Inhalation of powder (circle one) o Child 5-11 years 100-200mcg BDS o Child 12-17 years & adults 200-400mcg BDS, can be increased up to 800mcg
Communication to patient on inhaled corticosteroids?
- Reassure them that hardly any of the steroid is absorbed into the body so, except in very high-dose treatment, there are unlikely to be any serious side effects (or weight gain)
- Advise them to rinse their mouth and gargle after taking the inhaler to prevent development of a sore mouth or hoarse voice
- Show your patient how to use the device
Name of mucolytic?
Carbocysteine
Indications of mucolytics?
Clear secretions easier in COPD, bronchiectasis and CF
Mechanism of mucolytics?
- Reduce sputum viscosity
Side effects of mucolytics?
- Nausea and vomiting
- Itchy skin, rash
- GI bleeding
- Anaphylaxis reaction
Contraindications of mucolytics?
- Peptic ulcer
Names of alpha-adrenoreceptor antagonists?
Tamsulosin, doxazosin, alfuzosin
Indications of alpha-adrenoreceptor antagonists?
- 1st line medical option in BPH
- Add on treatment in resistant hypertension when CCB, ACEi and thiazide diuretics failed
Mechanism of alpha-adrenoreceptor antagonists?
- Alpha-1-adrenoreceptor blockers
o Found in smooth muscle, including blood vessels and urinary tract (bladder neck and prostate)
o Blockade induces relaxation causing vasodilatation and fall in BP and reduced resistence to bladder outflow
Side effects of alpha-adrenoreceptor antagonists?
- Postural hypotension
- Dizziness
- Syncope
- Sexual dysfunction
- Particularly prominent after first dose
When to avoid alpha-adrenoreceptor antagonists?
- Avoid in patients with postural hypotension, history of micturition syncope
Interactions of alpha-adrenoreceptor antagonists?
- Additive effect of antihypertensive drugs
o To avoid first-dose hypotension – omit dose of existing antihypertensives on day of first alpha blocker
Prescription of alpha-adrenoreceptor antagonists?
- Oral
- Doxazocin – BPH and hypertension – 1mg daily and increased after 1-2 weeks
- Tamsulosin – BPH – 400 micrograms daily
- Take at bedtime
Monitoring of alpha-adrenoreceptor antagonists?
- Lying and standing blood pressure
Names of PDE-5 inhibitors?
Sildenafil
Indications of PDE-5 inhibitors?
- Erectile dysfunction
- Primary pulmonary hypertension
Mechanisms of PDE-5 inhibitors?
- Selective phosphodiesterase type-5 inhibitor
o Found in smooth muscle of corpus cavernosum of penis and arteries of lung - For an erection to occur:
o Sexual stimulation releases NO, producing cGMP and causing arterial smooth muscle relaxation, vasodilatation and penile engorgement
o PDE5 responsible for breakdown of cGMP so sildenafil increases concentrations and erection quality
o Does not cause an erection without sexual stimulation - In pulmonary vasculature, causes arterial vasodilatation
Side effects of PDE-5 inhibitors?
- Flushing, headache, dizziness, nasal congestion
- Hypotension, tachycardia, palpitations
- Small risk of vascular events – MI, stroke
- If erection fails to subside for prolonged period of time despite absence of stimulation (priapism) – need urgent medical attention
- Colour distortion need urgent review
Contraindications of PDE-5 inhibitors?
- Recent stroke, ACS or significant history of CVD
- SBP <90mmHg
Cautions of PDE-5 inhibitors?
- Other antihypertensive drugs – hypotension
- Sickle cell, myeloma, leukaemia
Interactions of PDE-5 inhibitors?
- Do not prescribe with nitrates, nicorandil as can cause cardiovascular collapse
Prescription of PDE-5 inhibitors?
- Viagra (Sildenafil 25-100mg tablets) used as required 1 hour before sex
o Starting dose usually 50mg, maximum one per day
o Seek medical advice if erection persists two hours after sexual activity has finished - Tadalafil is longer-acting and can be used regularly for spontaneous sexual activity when frequent sex
- Revatio used for pulmonary hypertension
Names of GU antimuscarinics?
Oxybutynin, tolterodine, solifenacin
Indications of oxybutynin?
- Reduce urinary frequency, urgency and urge incontinence in overactive bladder (first-line if bladder training ineffective)
Mechanism of oxybutynin?
- Bind to muscarinic receptors and act as competitive inhibitor of acetylcholine
o Promotes bladder relaxation, reduce urinary frequency, urgency and urge incontinence - Selective for M3 receptor in bladder
Side effects of oxybutynin?
- Dry mouth, tachycardia, constipation, blurred vision
- Drowsiness, flushing, headache, nausea and vomiting
- Urinary retention
Contraindications of oxybutynin?
- UTI
- GI obstruction, intestinal atony
- BPH
Cautions of oxybutynin?
- Elderly
- Dementia
- Angle-closure glaucoma
- Arrhythmias/Acute MI/Cardiac surgery
Interactions of oxybutynin?
- Risk of adverse effects increased with other antimuscarinics - TCAs
Prescription of oxybutynin?
- Oxybutynin 5mg orally every 8-12 hours, dose increased as needed every week
Monitoring of oxybutynin?
- Prior to starting – urinalysis
- Review within a month and then every 6-12 months once stable
Indications of N-acetylcysteine? (Parvolex)
- Paracetamol poisoning antidote
- Prevent renal injury due to contract nephropathy
Mechanism of N-acetylcysteine?
- Paracetamol metabolised by conjugation with glucuronic acid and sulfate
- Small amount converted to N-acetyl-p-benzoquinone imine (NAPQI), which is hepatotoxic
o This is normally quickly detoxified by conjugation with gluthathione
o In overdose NAPQI causes liver damage - Acetylcysteine replenishes body’s supply of glutathione
Side effects of N-acetylcysteine?
- Diarrhoea, headache
- Anaphylactoid reaction (nausea, tachycardia, rash, wheeze)
o Histamine release independent of IgE
o Need to stop acetylcysteine and restart at slower rate
Caution of N-acetylcysteine?
- Asthma – do not delay treatment
- Increase PT and INR
Prescription of N-acetylcysteine?
- 150mg/kg over 1 hour (200ml 5% glucose)
- 50mg/kg over 4 hours (500ml 5% glucose)
- 100mg/kg over 16 hours (1L 5% glucose)
- Max dose for 110kg
Communication of N-acetylcysteine?
- If started within 8 hours, very effective
- Need to have continuous treatment for 21 hours
Monitoring of N-acetylcysteine?
- Serum paracetamol levels at 4 hours after ingestion as well as LFTs, U&Es, FBC and INR and repeated after the course of acetylcysteine
Names of 5-alpha reductase inhibitors?
Finasteride
Indications of 5-alpha reductase inhibitors?
2nd line treatment to BPH (after alpha blockers)
Mechanism of 5-alpha reductase inhibitors?
Inhibits 5-alpha reductase which converts testosterone into more active dihydrotestosterone which stimulates prostate growth
Reduce size of prostate
Side effects of 5-alpha reductase inhibitors?
Impotence Reduced libido Gynaecomastia Hair growth Breast cancer
Warnings of 5-alpha reductase inhibitors?
Exposure of a male foetus to 5α-reductase inhibitors may cause abnormal development of the external genitalia
Pregnant women do not take these drugs and are not exposed to them (e.g. by handling broken or damaged tablets or through semen during unprotected intercourse with a man taking these drugs)
Dose of 5-alpha reductase inhibitors?
Finasteride 5mg OD
