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Dyphylline is a xanthine derivative with pharmacologic actions similar to theophylline and other members of this class of drugs. Its primary action is that of bronchodilation, but it also exhibits peripheral vasodilatory and other smooth muscle relaxant activity to a lesser degree. The bronchodilatory action of dyphylline, as with other xanthines, is thought to be mediated through competitive inhibition of phosphodiesterase with a resulting increase in cyclic AMP producing relaxation of bronchial smooth muscle.
LUFYLLIN (dyphylline) is well tolerated and produces less nausea than aminophylline and other alkaline theophylline compounds when administered orally. Unlike the hydrolyzable salts of theophylline, dyphylline is not converted to free theophylline in vivo. It is absorbed rapidly in therapeutically active form and in healthy volunteers reaches a mean peak plasma concentration of 17.1 mcg/mL in approximately 45 minutes following a single oral dose of 1000 mg of LUFYLLIN.
Dyphylline exerts its bronchodilatory effects directly and, unlike theophylline, is excreted unchanged by the kidneys without being metabolized by the liver. Because of this, dyphylline pharmacokinetics and plasma levels are not influenced by various factors that affect liver function and hepatic enzyme activity, such as smoking, age, congestive heart failure, or concomitant use of drugs which affect liver function.
The elimination half-life of dyphylline is approximately two hours (1.8-2.1 hr) and approximately 88% of a single oral dose can be recovered from the urine unchanged. The renal clearance would be correspondingly reduced in patients with impaired renal function. In anuric patients, the half-life may be increased 3 to 4 times normal.
Dyphylline plasma levels are dose-related and generally predictable. The range of plasma levels within which dyphylline can be expected to produce effective bronchodilation has not been determined.
Dyphylline plasma concentrations can be accurately determined using high pressure liquid chromatography (HPLC) * or gas-liquid chromatography (GLC).
* See Valia, et al., J. Chromatogr. 221 : 170 (1980). Small quantities of pure dyphylline powder may be obtained from Wallace Laboratories, Cranbury, N.J. The internal standard, (beta)-hydroxyethyl-theophylline, may be obtained from companies supplying analytical chemicals.
Last reviewed on RxList: 1/20/2005
This monograph has been modified to include the generic and brand name in many instances.
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