DUOVENT HFA METERED DOSE INHALER

Indications

• Maintenance treatment of chronic obstructive pulmonary disease (COPD)
• Reversible airways obstruction in asthma
• Rhinorrhea associated with allergic and non-allergic rhinitis

Dosage

Children: For inhalation: Child 1 month

Adults: For inhalation: 20–40 micrograms 3–4 times a day. For intranasal administration: Apply 2–3 drops 2–3 times a day into each nostril.

Mechanism of action

Ipratropium bromide acts as a competitive antagonist of acetylcholine at muscarinic receptors. This inhibition prevents bronchoconstriction and promotes bronchodilation, thereby easing airflow in obstructive airway diseases. It primarily affects M1 and M3 muscarinic receptors in the airway smooth muscle and secretory glands, reducing mucus secretion and aiding ventilation.

Pharmacodynamics

The onset of action for ipratropium bromide typically occurs within 30 to 60 minutes after inhalation, with peak effects observed at this time. Its bronchodilatory effects can last for approximately 3 to 6 hours, making it suitable for multiple doses throughout the day. The drug is less effective than beta-agonists in producing bronchodilation but has a complementary role in therapy, especially for patients with chronic conditions requiring long-term management.

Pharmacokinetics

Ipratropium bromide is administered via inhalation, leading to localized action in the lungs with minimal systemic absorption. The systemic bioavailability is low, resulting in a reduced incidence of systemic side effects. It undergoes hepatic metabolism, with metabolites excreted primarily in the urine. The elimination half-life varies but is generally around 2 hours, allowing for flexible dosing intervals. The maximal effect is usually achieved within an hour post-administration.

Adverse effects

• dizziness
• epistaxis
• dry mouth
• nausea

Interactions

• beta2 agonists

Precautions

• Avoid spraying near eyes
• Patients with convulsive disorders should use with caution

Pregnancy

Ipratropium bromide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult a healthcare provider for individual assessment.

Breast-feeding

Ipratropium bromide is excreted in breast milk. Caution should be exercised when administering to nursing mothers.

Storage

Store at room temperature, away from light and moisture. Do not freeze.

Formulations

• Inhalation aerosol: 20-40 micrograms per actuation
• Nebulised solution: 250 micrograms per dose
• Nasal spray: 20 micrograms per actuation

Indications

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Bronchospasm

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations.

Adults: Refer to the BNF for specific dosing recommendations.

Mechanism of action

Fenoterol stimulates beta(2)-adrenergic receptors in the lung, which causes relaxation of bronchial smooth muscle, resulting in bronchodilation and increased bronchial airflow.

Pharmacodynamics

Fenoterol is a beta agonist designed to open up the airways to the lungs by decreasing bronchoconstriction. By activating beta-2 receptors, it enhances airflow and reduces airway resistance, making it effective in relieving symptoms of bronchospasm.

Pharmacokinetics

Fenoterol is rapidly absorbed after inhalation, with peak plasma concentrations typically occurring within 1 to 2 hours. It has a half-life of approximately 3 to 6 hours. The drug is metabolized in the liver and excreted primarily in the urine, with renal clearance being a significant pathway for its elimination.

Adverse effects

• Tachycardia
• Palpitations
• Tremor
• Headache
• Dizziness
• Nausea
• Muscle cramps

Precautions

• Use with caution in patients with cardiovascular disease
• Monitor in patients with hyperthyroidism
• Caution in patients with diabetes mellitus due to potential hyperglycemia

Pregnancy

Use only if clearly needed and the benefits outweigh the risks, as limited data are available on the safety of fenoterol during pregnancy.

Breast-feeding

Fenoterol is excreted in breast milk, therefore caution should be exercised when administering to breastfeeding women.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Inhaler
• Nebuliser solution

Indications

• Respiratory conditions (e.g., asthma, chronic obstructive pulmonary disease)
• Cough (e.g., as an antitussive)
• Anxiety and sleep disorders (when associated with specific formulations)

Dosage

Children: Refer to the BNF for Children for appropriate dosing information, as it is determined based on weight and age for the specific formulation.

Adults: Refer to the specific product monograph for dosing information, as it varies based on the drug formulation and indication.

Mechanism of action

Hydrobromides often act as competitive antagonists or agonists at specific receptor sites, depending on the drug involved. The exact mechanism can vary widely, but many hydrobromide-containing drugs modulate neurotransmitter activity, impacting various pathways in the body such as those involved in the central nervous system or respiratory function. The metabolic pathways include Phase I reactions primarily mediated by cytochrome P450 enzymes, which facilitate the functionalization and clearance of these compounds.

Pharmacodynamics

The pharmacodynamics of hydrobromide salts are largely determined by the specific drug they are associated with. Generally, hydrobromides may exhibit effects such as sedation, bronchodilation, or antitussive actions. The efficacy and adverse effects are influenced by the drug's receptor selectivity, affinity, and the pharmacological properties inherent to the parent compound.

Pharmacokinetics

Hydrobromides typically exhibit variable pharmacokinetic profiles depending on the specific drug formulation. They are generally absorbed rapidly following oral administration, with peak plasma concentrations occurring within a few hours. Metabolism primarily occurs in the liver through cytochrome P450 enzymes, particularly CYP2E1, among others. The elimination half-life varies but is often in the range of several hours, allowing for once or twice-daily dosing in many formulations. Excretion is usually via the kidneys, with metabolites being eliminated in urine.

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Use only if clearly needed and the potential benefits justify the potential risks to the fetus.

Breast-feeding

Caution is advised; consider the importance of the drug to the mother against potential risks to the breastfeeding infant.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Indications

• Chronic obstructive pulmonary disease (COPD)
• Asthma
• Acute bronchospasm
• Bronchospasm associated with COPD

Dosage

Children: For children aged 6 to 12 years, the recommended dose is 250 micrograms via inhalation, up to three times a day. For children under 6 years, dosing should be determined by a healthcare professional, and the use of ipratropium in this age group requires careful consideration.

Adults: The usual adult dose for ipratropium is 500 micrograms via inhalation, administered up to four times a day. The maximum dose should not exceed 2000 micrograms in 24 hours.

Mechanism of action

Ipratropium works by inhibiting the action of acetylcholine on muscarinic receptors in the bronchial smooth muscle, leading to bronchodilation. It prevents bronchoconstriction and reduces mucus secretion in the airways, thus improving airflow and decreasing respiratory distress.

Pharmacodynamics

The onset of action for ipratropium is typically within 15 minutes, with a peak effect occurring around 1 to 2 hours after administration. Its effect can last for approximately 4 to 6 hours. It is more effective in patients with COPD than in those with asthma, though it can be used in both conditions. The drug is sometimes used in conjunction with beta-agonists to enhance bronchodilation.

Pharmacokinetics

Ipratropium is poorly absorbed from the gastrointestinal tract and has minimal systemic bioavailability when inhaled. It has a half-life of approximately 1.5 hours. The drug is primarily excreted unchanged in the urine. Its pharmacokinetic profile supports its use in inhaled formulations, as it provides localized effects with reduced systemic side effects.

Contra-indications

• Hypersensitivity to ipratropium or any component of the formulation
• Acute exacerbation of bronchospasm

Adverse effects

• Dry mouth
• Cough
• Headache
• Nausea
• Dizziness
• Pharyngeal irritation

Interactions

• Clozapine: Unknown (additive effect)
• Beta 2-agonists: Unknown (increases risk of glaucoma)
• Second-generation antipsychotics: Unknown (additive effect)

Precautions

• Use with caution in patients with glaucoma
• Patients with prostatic hyperplasia or bladder neck obstruction should be monitored closely
• Caution in patients with cardiovascular disorders

Pregnancy

Ipratropium is classified as category B. Limited data suggest it is not expected to cause harm to the fetus.

Breast-feeding

Ipratropium is excreted in breast milk but is not expected to harm a nursing infant. Consider benefits versus risks.

Storage

Store in a cool, dry place, away from light. Do not freeze.

Formulations

• Inhalation solution
• Aerosol inhaler
• Nasal spray

Mechanism of action

Beta(2)-receptor stimulation in the lung causes relaxation of bronchial smooth muscle, bronchodilation, and increased bronchial airflow.

Pharmacodynamics

Fenoterol is a beta agonist designed to open up the airways to the lungs by decreasing bronchconstriction.