Reversible airways obstruction Acute severe asthma
DOSE IN NORMAL RENAL FUNCTION
Oral: depends on preparation used IV: Deteriorating asthma not previously treated with theophylline: 5 mg/kg (250– 500 mg) (as aminophylline) over at least 20 minutes Acute severe asthma: 500 mcg/kg/hour (as aminophylline) adjusted according to plasma-theophylline levels
20 to 50     : Dose as in normal renal function
10 to 20     : Dose as in normal renal function
<10           : Dose as in normal renal function. See ‘Other Information’
DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES
CAPD                : Not dialysed. Dose as in GFR <10 mL/min
HD                     : Dialysed. Dose as in GFR
<10           : mL/ min
HDF/high flux   : Dialysed. Dose as in GFR
<10           : mL/ min
CAV/VVHD      : Not dialysed. Dose as in normal renal function
IMPORTANT DRUG INTERACTIONS
Potentially hazardous interactions with other drugs
Antibacterials: increased concentration with azithromycin, clarithromycin, erythromycin, ciprofloxacin, norfloxacin and isoniazid; decreased plasma levels with erythromycin if erythromycin taken 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
Oral, IV
Rate of Administration
At least 20 minutes or 500 mcg/kg/hour depends on indication
Comments
–
OTHER INFORMATION
Therapeutic levels should be in the range
10 to 20     : mg/litre (55–110 micromols/litre) 50% of dose is removed by haemodialysis Studies have used it to protect against contrast nephropathy, with conflicting results .