Preparation: Vials contain 250mg aminophylline in 10mL
** PATIENTS ALREADY TAKING ORAL AMINOPHYLLINE/THEOPHYLLINE SHOULD NOT
RECEIVE A LOADING DOSE OF IV AMINOPHYLLINE **
Contraindications
 Hypersensitivity to aminophylline, ethylenediamine or those allergic to theophyllines, caffeine or theobromine.
 Acute porphyria.
 Aminophylline should not be administered concomitantly with other aminophylline/theophylline preparations.
(1,2)
How do I administer a
loading dose infusion of aminophylline?
*
Loading dose aminophylline infusion
Dilute required dose in 100mL of sodium chloride 0.9% or glucose 5%.
Maximum concentration 25mg/mL. Administer by intravenous infusion over
20-30 minutes using an infusion pump.
Maximum rate not to exceed 25mg/min.
Requires ECG and BP monitoring.
Note: Loading dose must be given with a doctor present.
How do I administer an intravenous
maintenance dose of aminophylline?
* Refer to Trust IV guide for further details
Maintenance dose for aminophylline
500 micrograms/kg/hr based on ideal body weight (2)
Dose may be lower in patients with heart failure, hepatic disease and in the elderly.
Consider:
Elderly or cor pulmonale a dose of 300 micrograms/kg/hr.
Congestive heart failure or liver impairment a dose of 100-200 micrograms/kg/hr.
Dilute 1mg aminophylline in 1mL (i.e. 500mg in 500mL) with sodium chloride
0.9% or glucose 5% * and administer by intravenous infusion over 24 hours using an infusion pump. Maximum concentration 25mg/mL. Maximum rate should not exceed 25mg/min.
Requires ECG and BP monitoring.
* Refer to Trust IV guide for further details
Aminophylline Monitoring and Adverse Effects
 Requires ECG, blood pressure and electrolyte monitoring.
 Therapeutic drug level monitoring required to prevent toxicity (see below).
 Rapid administration may cause hypotension, headache, anxiety, arrhythmias, insomnia and convulsions.
 Other possibly adverse effects – hypersensitivity reactions, rash, erythema, pruritis and tachycardia.
 Monitor for extravasation – extreme pH (8.6-9). Extravasation very likely to cause tissue damage.
Therapeutic Drug Monitoring
Refer to Guidelines for the Management of Common Medical Emergencies and the Use of Antimicrobial Drugs, current edition for further details.
Target aminophylline level is 10 – 20mg/L
Sampling Time Monitor at 4 – 6 hours post loading dose then at 24 hourly intervals during IV infusion or after 5 days following initiation of oral aminophylline/theophylline to prevent toxicity.
Time to steady state 2 days (following infusion where loading dose has not been given), 3 days
(following oral loading).
(1) Trust guidance
(2) BNF 62 September 2011 December 2011

Interactions
See BNF for full details
Aminophylline/ theophylline can interact with many drugs. All concurrent medications should be assessed for potential interactions before aminophylline/theophylline is initiated. Some clinically important interactions include:
Drugs/substances that increase aminophylline/theophylline concentrations leading to toxicity
Antibacterials e.g. azithromycin
Antifungals e.g. fluconazole
Antivirals e.g. aciclovir
Drugs/substances that decrease aminophylline/theophylline levels leading to sub therapeutic levels
Antiepileptics e.g. carbamazepine, phenobarbitone
Smoking
Calcium-channel blockers e.g. verapamil
Oestrogens
Interferons
Converting IV aminophylline to oral aminophylline
1.
Convert the hourly rate to the total amount administered in 24 hours by multiplying the hourly dose by 24.
2.
Divide this total amount by the dosing interval for oral administration, e.g. 2 for twice a day. It is assumed that the oral product is completely absorbed, i.e. the bioavailability is 100%.
For example:
If the IV aminophylline dose is 35mg /hr and the dosing interval for oral aminophylline is every 12 hours, i.e. twice a day, divide the total daily dose 840mg by 2. This gives the equivalent oral dose to be 420mg twice a day.
35mg x 24 = 420mg
2
A suitable aminophylline dosing regimen could be Phyllocontin Continus ® 225mg, 450mg (2x225mg tablets) twice a day.
Converting IV aminophylline to oral theophylline
Convert the hourly rate to the total amount administered in 24 hours by multiplying the hourly dose by 24.
In order to calculate the equivalent theophylline dose, multiply this total aminophylline dose by 0.8, which is the salt correction factor. It is assumed that the oral product is completely absorbed.
For example
If the IV aminophylline dose is 35mg/hr, then the total daily dose is 840mg. The oral theophylline dose is 840mg x 0.8 =
672mg daily
A suitable theophylline dosing regimen could be Uniphyllin Continus ® , 300mg in the morning and 400mg in the evening.
Oral aminophylline and theophylline modified release preparations available
Brand
Phyllocontin Continus ®
Aminophylline
Available strengths
225mg
Dosing frequency
Twice daily
Nuelin SA ®
Slo-Phyllin ®
Uniphyllin Continus ®
Brand
Theophylline
Available strengths
175mg
60mg, 125mg, 250mg
200mg, 300mg, 400mg
Dosing frequency
Twice daily
Twice daily
Twice daily
December 2011