Source: Health Products Regulatory Authority (IE) Revision Year: 2017 Publisher: Mundipharma Pharmaceuticals Limited, Millbank House, Arkle Road, Sandyford, Dublin 18, Ireland
Pharmacotherapeutic group: Drugs for obstructive airways disease, xanthines
ATC code: R03DA05
Aminophylline (theophylline) is a bronchodilator. In addition it affects the function of a number of cells involved in the inflammatory processes associated with asthma and chronic obstructive airways disease. Of most importance may be enhanced suppressor T-lymphocyte activity and reduction of eosinophil and neutrophil function. These actions may contribute to anti-inflammatory prophylactic activity in asthma and chronic obstructive airways disease.
Theophylline may contribute to the prevention of the late asthmatic inflammatory response due to immunological stimuli.
Following oral administration of PHYLLOCONTIN CONTINUS tablets, the delivery of theophylline is controlled and at steady state, peak concentrations are typically seen after approximately 5 hours.
An effective plasma concentration is considered to be 5-12 micrograms/ml, although plasma concentrations up to 20 micrograms/ml may be necessary to achieve efficacy in some cases. Do no exceed 20 micrograms/ml.
Theophylline is distributed through all body compartments; approximately 60% is bound to plasma proteins.
Theophylline is metabolised in the liver to 1, 3 dimethyluric acid, 1 methyluric acid and 3-methylxanthine.
Theophylline and its metabolites are excreted mainly in the urine. Approximately 10% is excreted unchanged.
The predominant factors which alter theophylline clearance are: age, body weight, diet, smoking habits, other drugs and cardiorespiratory or hepatic disease. Clearance is increased in children compared to values observed in adult subjects. Clearance decreases toward adult values in late teens.
In vitro and in vivo assays have shown both positive and negative genotoxic results for theophylline. However, oral theophylline administered daily to rats and mice for 2 years did not show carcinogenicity. Therefore, it is unlikely that theophylline poses a carcinogenic risk in man.
Theophylline has been shown to have effects upon the male reproductive system in rodents, but at doses considered in excess of the maximum human dose indicating little relevance to clinical use.
Several embryofetal development studies in rats, mice and rabbits have demonstrated developmental effects independent from maternal toxicity at high doses of theophylline. Therefore theophylline should be considered to have the potential for developmental toxicity in man
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