Aminophylline

CLINICAL USE

Reversible airways obstruction

Acute severe asthma

DOSE IN NORMAL RENAL FUNCTION

Modified release: 225–450 mg twice daily
IV loading dose: 5 mg/kg (250–500 mg)
Maintenance dose: 0.5 mg/kg/hour adjusted
according to levels

PHARMACOKINETICS

Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :
420.4

%Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :
40–60 (theophylline)

%Excreted unchanged in urine &nbsp &nbsp :

<10 &nbsp &nbsp &nbsp &nbsp &nbsp :

Volume of distribution (L/kg) &nbsp &nbsp &nbsp :
0.4–0.7 (theophylline)

half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp :
4–12/Unchanged
(theophylline)

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 &nbsp &nbsp : Oral: Dose as in normal renal
function and adjust in accordance
with blood levels
IV: Dose as in normal renal function
and adjust in accordance with blood
levels

10 to 20 &nbsp &nbsp : Oral: Dose as in normal renal
function and adjust in accordance
with blood levels
IV: Dose as in normal renal function
and adjust in accordance with blood
levels

<10 &nbsp &nbsp &nbsp &nbsp &nbsp :
Oral: Dose as in normal renal
function and adjust in accordance
with blood levels
IV: Dose as in normal renal function
and adjust in accordance with blood
levels

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp:
Not dialysed. Dose as in
GFR <10 mL/min Monitor blood
levels. See ‘Other Information’

HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :
Not dialysed. Dose as in
GFR <10 mL/min. Monitor blood
levels. See ‘Other Information’

HDF/high flux &nbsp :
Unknown dialysability. Dose as in
GFR <10 mL/min Monitor blood
levels. See ‘Other Information’

CAV/VVHD &nbsp &nbsp &nbsp:
Not dialysed. Dose as in GFR=10–
20 mL/min Monitor blood levels.
See ‘Other Information’

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Antibacterials: increased concentration

with azithromycin, clarithromycin,
erythromycin, ciprofloxacin, norfloxacin
and isoniazid; decreased erythromycin
levels if erythromycin is given orally;
increased risk of convulsions if given
with quinolones; rifampicin accelerates
metabolism of theophylline

Antidepressants: concentration increased

by fluvoxamine – avoid concomitant use
or halve theophylline dose and monitor
levels; concentration reduced by St John’s
wort – avoid concomitant use

Anti-epileptics: metabolism increased

by carbamazepine and primidone;
concentration of both drugs increased
with phenytoin

Antifungals: concentration increased by

fluconazole and ketoconazole

Antivirals: metabolism of theophylline

increased by ritonavir

Calcium-channel blockers: concentration

increased by diltiazem and verapamil and
possibly other calcium-channel blockers

Tacrolimus: may increase tacrolimus levels

Ulcer-healing drugs: metabolism inhibited

by cimetidine; absorption possibly reduced
by sucralfate

ADMINISTRATION

Reconstition

–

Route

IV, oral

Rate of Administration

Loading dose over 20 minutes by slow IV

injection

Comments

Can be added to glucose 5%, sodium

chloride 0.9% and compound sodium
lactate

Minimum volumes range from 2–25 mg/

mL, give concentrated solution via central
line.

OTHER INFORMATION

Aminophylline: 80% theophylline + 20%

ethylenediamine

In bodily fluids, aminophylline rapidly

dissociates from ethylenediamine and
releases free theophylline in the body.
It is therefore not present in the body
long enough to be dialysed, whereas
theophylline is dialysed, see theophylline
monograph

Optimum response obtained at plasma

theophylline levels of 10 to 20 mg/L (55–110
micromol/L)

Increased incidence of GI and neurological

side effects in renal impairment at plasma
levels above optimum range

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