β2 agonist - GsPCR: Adenylate cyclase activated, cAMP

On cell membranes: ↑Na+/K+ ATPase activity and hyperpolarisation

Mild β1 agonist effects

- Competitive inhibition of cholinergic receptors in bronchial smooth muscle leading to inhibition of the bronchoconstrictor effect and vagal efferent impulses
- M3 are receptors for bronchial smooth muscle contraction and mucous production
- Inhibition of M3-R leads to decreased IP3/DAG and therefore decreased calcium required for bronchoconstriction

CVS:
- At high doses, especially IV, B1 effects cause increased inotropy and chronotropy
- At lower doses, B2 effects predominate and may cause a decreased SVR due to skeletal muscle vasodilation
- May precipitate arrhythmias, particularly in the presence of hypokalaemia
Resp:
- Bronchodilation, leading to increased FEV1
- Interferes with hypoxic pulmonary vasoconstriction and may precipitate shunt leading to hypoxia
Metabolic/Other:
- Na/K/ATPase is stimulated and transports K into cells leading to hypokalaemia
- Increased blood glucose
- Beta adrenergic activity leads to increased production of lactate
- Tremor
Uterus:
- Relaxes gravid uterus
- 10% crosses the placenta and causes fetal tachycardia

CVS
- Cardiovascular effects are minimal after inhaled
- M2 effects may lead to tachycardia, increased CO and increased BP particularly when given IV
Resp
- Bronchodilation
- May cause a small decreased mucous production
GIT
- Dry mouth
- Decreased gastric secretions when given orally
CNS
- Unable to cross BBB

After inhalation, about 10% of the dose reaches the bronchial tree. The remainder is swallowed and undergoes gastrointestinal absorption and first-pass metabolism.

Inh
Poor bioavailability PO: 30% Inh: 5%

Only weak protein binding

Very weak protein binding

Vd (IV) 4-5L/kg

Vd 4.6L/kg

Converted by liver to inactive metabolite (esterified / oxidative deamination / conjugation with glucuronide)

Metabolized by GIT by CYP450 enzymes.

Excreted urine as 40% free dug and 60% metabolite
Small amount in faeces

80-100% urine (unchanged), rest faeces
Mostly in faeces if given orally

T1/2 5hrs

T1/2 1.6hrs

Adverse effects include tremor, palpitations or tachycardia, anxiety or insomnia, hypokalaemia, hyperglycaemia and lactic acidosis. Nausea, vomiting and postural hypotension may also occur.

Paradoxical bronchospasm
headache, dizziness,
nausea, dry mouth,
shaking (tremors),
nervousness, or.
cold symptoms such as stuffy nose, sneezing, cough, or sore throat.

Synthetic sympathomimetic amine

racemic mixture of the R- and S-isomers. The R-isomer has 150 times greater affinity for the beta2-receptor than the S-isomer and the S-isomer has been associated with toxicity

Synthetic quaternary ammonium compound derived from atropine

Short-acting beta-2 adrenergic agonist bronchodilator with uterine-relaxant effects.

BRONCHODILATORS - ANTIMUSCARINIC

(i) the symptomatic relief and prevention of bronchospasm due to bronchial asthma, chronic bronchitis, reversible obstructive airway disease, and other chronic bronchopulmonary disorders in which bronchospasm is a complicating factor, and/or (ii) the acute prophylaxis against exercise-induced bronchospasm and other stimuli known to induce bronchospasm

in combination with inhaled beta-agonist systemic corticosteroids for the management of severe exacerbations of asthma flares requiring treatment
bronchodilator for maintenance treatment of bronchospasm associated with chronic obstructive pulmonary disease including chronic bronchitis and emphysema
Studied for Rhinorrhoea and Sialorrhea

short-acting, selective beta2-adrenergic receptor agonist used in the treatment of asthma and COPD.

quaternary ammonium derivative of atropine that acts as an anticholinergic agent.

Level 3 for Tocolysis

Level 2 for Bronchodilation (see in relevant table)

Level 2

Beta-2 adrenoceptor agonism increases intracellular cAMP, producing bronchial smooth-muscle relaxation and uterine relaxation.

Competitive inhibition of cholinergic receptors

- Clear colourless solution containing 50-500mcg/ml after dilution for IV infusion
- Metered dose inhaler (100mcg) and dry powder (200-400mcg) for inhalation
- Clear colourless solution containing 2.5-5mg/ml for nebulization
- Oral preparation (syrup or tablets)

Isotonic solution containing 0.25mg/ml for nebulization (100-500mcg Q6hr) or as a MDI of 200mcg/dose (1-2 puffs Q6)
Maximum effect achieved in 1.5-2 hours and lasts 4-6 hours

Inh/Neb/IV

Inh/Neb

Appears to potentiate NDMR