What are the recommended doses of salbutamol (albuterol) and theophylline (doxophylline) for a geriatric patient with asthma and potential comorbidities such as impaired renal function or cardiac disease?

Medication Dosing for Asthma in Geriatric Patients

Salbutamol (Albuterol) Dosing

For acute severe asthma in geriatric patients, use nebulized salbutamol 5 mg repeated every 4-6 hours if improving, or more frequently (every 15-30 minutes initially) if not responding adequately. 1

Acute Asthma Management

• Initial treatment: Nebulized salbutamol 5 mg via oxygen-driven nebulizer (40-60% oxygen) 1
• Reassess at 15-30 minutes after nebulization to determine response 1
• If improving (PEF >50-75% predicted): Repeat salbutamol 5 mg every 4-6 hours 1
• If not improving or severe features persist: Repeat salbutamol 5 mg every 30-60 minutes initially, then hourly as needed 1
• Life-threatening features: Continue hourly nebulization with consideration for IV aminophylline if no improvement 1

Alternative Delivery When Nebulizer Unavailable

• Use metered-dose inhaler with large volume spacer: 2 puffs repeated 10-20 times (equivalent to 200-400 mcg per treatment session) 1

Chronic Asthma Maintenance

• Mild episodes: 200-400 mcg via hand-held inhaler four times daily 1
• Moderately severe: 400 mcg four times daily or switch to nebulizer 1
• Patients requiring short-acting β-agonists more than 2-3 times daily should be escalated to inhaled corticosteroids 1

Special Geriatric Considerations

• First treatment must be supervised in elderly patients, as β-agonists may rarely precipitate angina 1
• Elderly patients may experience more pronounced tremor and blood pressure changes, though long-term treatment may reduce these effects through β-receptor subsensitivity 2
• Hypokalaemia risk is increased, particularly when combined with diuretics, corticosteroids, or theophyllines—all common in geriatric polypharmacy 2

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Theophylline/Aminophylline Dosing

Theophylline should be used cautiously in geriatric patients at lower doses targeting plasma concentrations of 5-10 mg/L, with sustained-release formulations at 400 mg/day being safe and effective. 3, 4

Acute Severe Asthma (IV Aminophylline)

Critical warning: Do NOT give bolus aminophylline if the patient is already taking oral theophyllines 1, 5

• Indication: Reserved only for life-threatening asthma or failure to improve after nebulized β-agonists, systemic corticosteroids, and ipratropium 5
• Loading dose: 250 mg IV over 20 minutes (if not on oral theophyllines) 1
• Maintenance infusion: 0.014 mg/kg/min (approximately 1 mg/min for 70 kg patient) 6
• Aminophylline shows superior initial bronchodilation compared to IV salbutamol in acute asthma 6

Chronic Asthma Management

• Sustained-release theophylline: 400 mg/day is safe in elderly patients with asthma or COPD 3
• Target plasma concentration: 5-10 mg/L (lower than traditional 10-20 mg/L range) to minimize side effects while maintaining anti-inflammatory benefits 4
• Blood levels ≤15 mcg/ml were achieved in 87% of elderly patients on 400 mg/day without correlation to adverse events 3
• Consider as second-line oral bronchodilator after inhaled agents 1

Geriatric-Specific Precautions

• Higher risk populations: Patients with hepatic disease (odds ratio 1.81) and arrhythmias (odds ratio 1.88) have increased adverse event rates 3
• Common adverse effects in elderly: nausea (1.05%), loss of appetite (0.56%), hyperuricemia (0.42%), palpitations (0.39%) 3
• Serious risks: Sinus and supraventricular tachycardias, though convulsions were not reported in large elderly cohort 2, 3
• Drug interactions: Theophyllines have extensive drug-drug interaction profile—critical concern in geriatric polypharmacy 2
• Pharmacokinetic changes with aging affect absorption, distribution, metabolism, and excretion 7

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Note on Doxofylline

The evidence provided does not contain specific dosing information for doxofylline. The guidelines reference theophylline and aminophylline specifically. Doxofylline is a theophylline derivative with potentially fewer cardiac and CNS side effects, but specific geriatric dosing should follow manufacturer recommendations and local formulary guidance.

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Critical Comorbidity Adjustments

Renal Impairment

• Salbutamol: No specific dose adjustment required as primarily metabolized hepatically, but monitor for increased systemic effects 2
• Theophylline: Use lower maintenance doses and monitor plasma levels more frequently, as renal clearance contributes to elimination 2

Cardiac Disease

• Both medications require heightened caution 1, 2
• Supervise first β-agonist treatment to monitor for angina precipitation 1
• Theophylline's chronotropic effects pose particular risk in arrhythmia patients 2, 3
• Consider ipratropium bromide as safer alternative bronchodilator in high-risk cardiac patients 2

Key Pitfall to Avoid

Never combine high-dose β-agonists with theophyllines and corticosteroids without monitoring potassium levels—this triple combination dramatically increases hypokalaemia risk in elderly patients on diuretics 2