Can Deriphyllin Injection Be Given Now?
No, do not administer the deriphyllin (aminophylline/theophylline) injection to this patient who has already taken oral theophylline tonight. The loading dose must be omitted in patients already taking oral theophyllines to avoid potentially life-threatening toxicity 1.
Critical Safety Concern
The patient has already received oral theophylline at 9:30 PM, making a loading dose of intravenous aminophylline contraindicated due to risk of theophylline toxicity. 1, 2
- If IV aminophylline is deemed necessary for this patient with severe asthma, you can only proceed with a maintenance infusion without a loading dose 1
- The maintenance infusion rate should be 0.5-0.7 mg/kg/hour 1
- Serum theophylline levels must be monitored routinely due to wide interpatient variability in metabolism 1
When IV Aminophylline Is Indicated
Aminophylline should only be considered if the patient shows unsatisfactory progress after initial treatments with nebulized β-agonists (which she received as salbutamol at 11 PM), systemic corticosteroids (betamethasone given orally), and potentially nebulized ipratropium 2.
- Reserved specifically for patients with life-threatening features or those who fail to improve with first-line therapies 2
- Current guidelines emphasize that systemic corticosteroids and inhaled beta-agonists are the primary treatments, with theophylline serving only as adjunctive therapy in severe cases not responding to initial treatment 1
Toxicity Risk Factors
Theophylline has a narrow therapeutic window with serious adverse effects at higher concentrations: 1
- At therapeutic doses: insomnia, gastric upset, aggravation of ulcer or reflux 1
- At higher concentrations: CNS stimulation, headache, seizures, hematemesis, hyperglycemia, and hypokalemia 1
- Multiple factors affect serum concentrations including diet, febrile illness, age, and other medications 1
Alternative Management Approach
Before considering IV aminophylline, ensure the patient has received adequate first-line therapy: 3, 2
- Continue nebulized salbutamol at 4-6 hourly intervals (can be used more frequently if required) 3
- Ensure systemic corticosteroids are on board (the oral betamethasone should be adequate, though prednisolone 30 mg/day or IV hydrocortisone 100 mg are standard alternatives) 3
- Consider adding nebulized ipratropium bromide 0.25-0.5 mg if not already given, especially for severe exacerbations 3
- Both salbutamol and ipratropium may be administered together if response to either alone is poor 3
If IV Aminophylline Is Still Necessary
Only proceed with maintenance infusion (no loading dose) and implement strict monitoring: 1