Drugs theophylline

The FT-Raman spectra of a range of drugs (theophylline, indomethacin, diclofenac, and promethazine) in several polymers (sodium alginate, hydroxy-propylmethylcellulose, and polyethylene glycol) have been obtained [56,57]. In these studies, the linearity of response of Raman scattering to species concentration was exploited to analyze diclofenac at concentrations of 0.01-6.0% w/w... 

FIGURE 3-4 Relationship between dosing interval and plasma concentrations of the antiasthmatic drug theophylline. A constant intravenous infusion [shown by the smoothly rising line] yields a desired plasma level of 10 mg/L. The same average plasma concentration is achieved when a dose of 224 mg is taken every 8 hours, or a dose of 672 mg every 24 hours. However, note the fluctuations in plasma concentration seen when doses are taken at specific hourly intervals. 

Metabolites and substrates (urea, triglycerides, bili-rubine, lactate), enzymes (the measurands are the enzyme activities), hormones (aldosterone, estradiol, es-triol, testosterone, thyroxin), drugs (theophylline, digoxin, digitoxin), total proteinAs far as possible, isotope dilution mass spectrometry is used for the primary measurements in both institutes (e.g. [4]). 

It is known that the antibiotic rifampicin increases the amount of drug metabolizing enzyme present in the liver and consequently increases the rate of elimination of a wide range of other drugs. This experiment is designed to detect whether rifampicin affects the metabolic removal of the anti-asthma drug theophylline. Any such interaction could be of real practical importance. A marked increase in the elimination of theophylline would result in inadequate treatment of the patient s asthma. 

The in vitro release profiles of the model drug theophylline are shown below in Figures A1 through A10. 

One of the most widely prescribed of these drugs — theophylline — has recently come under close scrutmy as a possible cause of bizarre and violent behavior. Theophylline is the active principle of tea, a near relative of caffeine. For many years most asthmatics have swallowed large daily doses of this stimulant, considered a safe and effective drug. Now, with increasing evidence that it can produce serious behavioral changes, its days of use as a medical treatment may be numbered. 

Herbal effects on absorption can affect the bioavailability of antibiotics and has been demonstrated for Khat (Catha endulis) users (Attef et al., 1997). Absorption and decreased metabolism of the asthma drug theophylline are also affected by piperine from black pepper (Piper nigrum, Piper longum). 

One case of lowered theophylline level was reported in a patient taking St. John s wort, theophylline, and numerous other drugs. Theophylline level returned to normal after St. John s wort was stopped (Nebel et al. 1999). 

A decrease in serum levels and a dose-dependent increase in the rate of clearance of the drug theophylline was observed in rats orally administered 1 or 2 g/kg of an ethanol extract of evodia or 50 mg/kg of the compound rutaecarpine daily for 3 days prior to intravenous administration of 2 mg/kg theophylline, a CYP1A2 substrate (Jan et al. 2005 Ueng et al. 2005). 

The first example, depicted in Fig. 6, describes the synthesis and evaluation of a polymer imprinted with the bronchodilating drug theophylline, which is used in the treatment of asthma. Originally published in the journal Nature [2], this work drew considerable attention to the field of molecular imprinting because it was the first study to show that an MIP could be substituted for a natural antibody in a standard clinical assay. The MIP and antibody-based assays exhibit similar selectivities, and both can discriminate between theophylline and structurally related compounds. An equilibrium binding assay is described which uses radiolabeled theophylline as a marker. Data are presented for which nonradioactive theophylline, caffeine, and theobromine are used in competitive binding assays. These assays provide valuable information about the capacity and selectivity of the MIP. 

V. PROTOCOL 1 AN IMPRINTED POLYMER SPECIFIC FOR THE DRUG THEOPHYLLINE... 

The diffusion behaviour of low molec.wt. drugs (theophylline, proxyphylline and oxprenolol.HCl) from pH-sensitive, anionic, initially glassy copolymer networks of 2-hydroxyethyl methacrylate with acrylic acid and/or methacrylic acid was studied as a function of pH, ionic strength and the nature of the dissolution medium. The dissolution media used were simulated physiological fluids such as simulated gastric fluid, a phosphate buffer of pH 7.4 and a glutarate buffer solution of pH 7.19 refs. USA... 

Figure 3 Noncovalent imprinting by using a drug (theophylline) as template. Step 1 Preorganization of functional monomers through noncovalent interactions. Step 2 Polymerization of preorganized functional monomers. Step 3 Removal of the template.

Figure 4. Schematic representation of the drug (theophylline) polyrotaxane conjugate.

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