Nifedipine Aminophylline

Kalra L, Bone MF, Ariaraj SJP. Nifedipine-aminophylline interaction J Clin Pharmacol (1988) 28,1056-7. 

Acute hypertensive episodes have been controlled with chlorpromazine or phentolamine (both of which are alpha blockers). Hydralazine, nifedipine and aminophylline have also been used. Reflex bradycardia may be managed wifh afropine and the pre-emptive use of glycopyrrolate has also been suggested. ... 

In one study, slow-release nifedipine 20 mg twice daily reduced the mean steady-state theophylline levels of 8 asthmatics by 30%, from 9.7 to 6.8 mg/L. Levels fell by 50%, 56%, and 64% in three of the patients, but no changes in the control of the asthma (as measured by peak flow determinations and symptom scores) were seen. However, many other studies have found no changes, or only small to modest changes, in the pharmacokinetics of theophylline (given as oral theophylline or as intravenous lysine theophylline or aminophylline") in healthy subjects " or asthmatic patients " given nifedipine. The control of the asthma was unchanged by nifedipine. " Yet another study found that the combined use of slow-release theophylline and nifedipine improved pulmonary function and blood pressure control. ... 

In contrast, there are 2 case reports of patients who developed theophylline toxicity (theophylline levels raised to 30 mg/L and 41 mg/L), apparently due to the addition of nifedipine. In one case, the toxicity recurred on rechallenge, and resolved when the theophylline dosage was reduced by 60%. During a Swan Ganz catheter study of patient response to nifedipine for pulmonary hypertension, 2 patients developed serious nifedipine adverse effects, which responded to intravenous aminophylline. ... 

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