Theophylline monitoring

Theophylline Decreased metabolism of theophylline Monitor theophylline SDC... 

BETA-BLOCKERS THEOPHYLLINE t plasma levels of theophylline with propranolol Propranolol exerts a dose-dependent inhibitory effect on the metabolism of theophylline Monitor theophylline levels during propranolol co-administration... 

PENTOXIFYLLINE BRONCHODILATORS- THEOPHYLLINE Possibly t theophylline levels Uncertain possibly competitive inhibition of theophylline metabolism (pentoxifylline is also a xanthine derivative) Warn patients of the possibility of adverse effects of theophylline monitor levels if necessaiy... 

METHOTREXATE BRONCHODILATORS -THEOPHYLLINE Possible t in theophylline levels Possibly inhibition of CYP2D6-mediated metabolism of theophylline Monitor clinically for toxic effects and advise patients to seek medical attention if they have symptoms suggestive of theophylline toxicity. Measure theophylline levels before, during and after co-administration... 

Numerous studies on clinical pharmacokinetic monitoring have demonstrated positive clinical outcomes. The reader is directed to a comprehensive review of the evidence to support such definitive outcomes.Some examples of positive clinical outcomes for theophylline monitoring cited in the comprehensive review include decreased length of stay and decreased toxicity. For traditional aminoglycoside monitoring, examples include decreased length of treatment,decreased length of hospital stay, ° " decreased febrile periods decreased duration to return to normal or baseline temperature, decreased duration to stabilize heart... 

It is established that changes in thyroid status may affect how the body handles theophylline. Monitor the effects and anticipate the possible need to begin to reduce the theophylline dosage if treatment for hyperthyroidism is started (e.g. with radioactive iodine, carbimazole, thiamazole, propylthiouracil, etc.). Similarly, anticipate the possible need to increase the theophylline dosage if treatment is started for hypothyroidism (e.g. with levothyroxine). Stabilisation of the thyroid status may take weeks or even months to achieve so that if monitoring of the theophylline dosage is considered necessary, it will need to extend over the whole of this period. 

The nurse can give some of these drug (for example, aminophylline or theophylline) IV, either direct IV or as an IV infusion. When giving theophylline or aminophylline IV, the nurse monitors die patient for hypotension, cardiac arrhythmias, and tachycardia. If a bronchodilator is given IV, the nurse administers it through an infusion pump. The nurse checks die IV infusion site at frequent intervals because these patients may be extremely restless, and extravasation can occur. 

Remember that frequent monitoring of theophylline serum levels is important. 

Use of zileuton is uncommon due to the need for dosing four times a day, potential drug interactions, and the potential for hepatotoxicity with the resulting need for frequent monitoring of liver enzymes. In patients started on zileuton, serum alanine aminotransferase concentrations should be monitored before treatment begins, monthly for the first 3 months, every 2 to 3 months for the remainder of the first year, and then periodically thereafter for as long as the patient continues to receive the medication. Zileuton also inhibits the cytochrome P-450 (CYP) mixed function enzyme system and has been shown to decrease the clearance of theophylline, R-warfarin and propranolol.34... 

Monitor theophylline levels with goal serum concentrations in the range of 5 to 15 mcg/mL (28 to 83 4mol/L). Trough levels should be obtained 1 to 2 weeks after initiation of treatment... 

While generally not of major concern, omeprazole may inhibit the metabolism of warfarin, diazepam, and phenytoin lansoprazole may decrease theophylline concentrations. Drug interactions with omeprazole are of particular concern in patients who are considered slow metabolizers, as are approximately 3% of the Caucasian population. Unfortunately, it is unclear which patients have the polymorphic gene variation that makes them slow metabolizers.17 The metabolism of esomeprazole may also be altered in patients with this polymorphic gene variation. Patients on potentially interacting drugs should be monitored for development of drug-related problems. 

Only a small number of drug interactions have been reported with donepezil. In vitro studies show a low rate of binding of donepezil to cytochrome P-450 (CYP)3A4 or 2D6. Whether or not donepezil has the potential for enzyme induction is not known. No interactions with theophylline, cimeti-dine, warfarin, digoxin, or ketoconazole have been documented. In vitro studies show that inhibitors of CYP3A4 and 2D6 have the potential to inhibit the metabolism of donepezil. The clinical relevance of this is unknown. However, monitoring for possible increased peripheral side effects is advised... 

Disulfiram inhibits CYP1A2, resulting in an increase in theophylline blood levels monitor theophylline blood concentration may need to decrease theophylline dose. 

In the clinical area, the largest share of analytical methods development and publication has centered on the determination of theophylline in various body fluids, since theophylline is used as a bronchodilator in asthma. Monitoring serum theophylline levels is much more helpful than monitoring dosage levels.44 Interest in the assay of other methylxanthines and their metabolites has been on the increase, as evidenced by the citations in the literature with a focus on the analysis of various xanthines and methylxanthines. 

Because of large interpatient variability in theophylline clearance, routine monitoring of serum theophylline concentrations is essential for safe and effective use. A steady-state range of 5 to 15 mcg/mL is effective and safe for most patients. 

Fig. 80-3 gives recommended dosages, monitoring schedules, and dosage adjustments for theophylline. 

Use of zileuton is limited due to the potential for elevated hepatic enzymes (especially in the first 3 months of therapy), and inhibition of the metabolism of some drugs metabolized by CYP3A4 (e.g., theophylline, warfarin). Serum alanine aminotransferase should be monitored before treatment and then periodically thereafter. 

Dose adjustments should generally be made based on trough serum concentration results. A conservative therapeutic range of 8 to 15 mcg/mL is often targeted, especially in elderly patients, to minimize the likelihood of toxicity. Once a dose is established, concentrations should be monitored once or twice a year unless the disease worsens, medications that interfere with theophylline metabolism are added, or toxicity is suspected. 

T. M. Li and J. F. Burd, Enzymic hydrolysis of intramolecular complexes for monitoring theophylline in homogeneous competitive protein-binding reactions, Biochem. Biophys. Res. Commun. 103, 1157-1165 (1981). 

Haruta S, Kawai K, Nishii R, Jinnouchi S, Ogawara K-I, Higaki K, Tamura S, Arimori K, Kimura T (2002) Prediction of plasma concentration-time curve of orally administered theophylline based on scintigraphic monitoring of gastrointestinal transit in human volunteers. Int. J. Pharm. 233 179-190. 

Examples of solvent-mediated transformation monitoring include the conversion of anhydrous citric acid to the monohydrate form in water [235,236], CBZ with water [237] and ethanol-water mixtures [238,239], and cocrystallization studies of CBZ, caffeine, and theophylline with water [240]. Raman spectroscopy was used to monitor the crystallization rate and solute and solvent concentrations as griseofulvin was removed from an acetone solution using supercritical CO2 as an antisolvent [241]. Progesterone s crystallization profile was monitored as antisolvent was added [242]. 

---