Our library of drug research abstracts drawn from the medical literature is updated on a regular schedule, and you can be assured that new theo-dur research articles will be listed here shortly after becoming available to us.
Related Sponsors
Medical research on theo-dur
Eur J Pharm Biopharm. 2008 Apr 29;
Dukić-Ott A, De Beer T, Remon JP, Baeyens W, Foreman P, Vervaet C
Pellet cores containing modified starch (high-amylose, crystalline and resistant starch) as the main excipient were enteric-coated with an Eudragit((R)) L30 D-55 based dispersion. The polymer weight gain was from 15% to 30% (w/w). Pellet cores were prepared using piroxicam (2.5% w/w, poor water solubility) and anhydrous theophylline (2.5% and 25% w/w, coarse and micronised powder, medium water solubility) as model drugs. Next to the water solubility, particle size and concentration of the model drugs, the influence of sorbitol (0% and 10%, w/w) and drying method (oven and fluid-bed) on pellet yield, size (Feret mean diameter), sphericity (aspect ratio, AR and two-dimensional shape factor, e(R)), friability, surface morphology and drug release were evaluated. Binder (HPMC) and granulation liquid (water) concentration were optimised to obtain maximum yield (size fraction between 900 and 1400mum) and acceptable sphericity (AR
The influence of a newly developed quinolone: antofloxacin, on CYP activity in rats.
Eur J Drug Metab Pharmacokinet. 2008 Jan-Mar; 33(1): 1-7
Xu X, Liu HY, Liu L, Xie L, Liu XD
To investigate a newly developed quinolone antibiotics, the effect of antofloxacin hydrochloride on cytochrome P450 isoforms in rats was examined. A cocktail approach was adopted. Theophylline (CYP1A2), midazolam (CYP3A), chlorzoxazone (CYP2E1), dextromethorphan (CYP2D6), omeprazole (CYP2C19) and diclofenac (CYP2C9) were used as probes in the study, and own control was adopted. In Protocol 1, probes were given to rats simultaneously by co-administration with antofloxacin. The blood samples were obtained at designated time, and plasma concentrations of the six probes were determined by LC-MS. The pharmacokinetic parameters were calculated and compared in experimental groups in the absence and presence of antofloxacin. The result showed that the presence of antofloxacin resulted in a significant increase in theophylline values of AUC0-T and t1/2 (PAUC0-T = 0.0004 vs control Pt1/2 = 0.005 vs control), indicating that antofloxacin delayed the clearance of theophylline. In Protocol 2, the probes' pharmacokinetic parameters were compared in rats that received six probes before and after 14.5 days of consecutive administration of antofloxacin (15 mg x kg(-1), given orally, twice daily). The results suggested that the AUC0-T of chlorzoxazone was significantly decreased (P = 0.024), while that of dextromethorphan was significantly increased (P = 0.027). In conclusion, these results indicated that antofloxacin may inhibit the activity of CYP1A2, thus delaying the clearance of its substrates, and may have a slight inhibitory effect on CYP2D6 as well as an inductive effect on CYP2E1 following chronic administration.
J Pediatr. 2008 Jun 3;
Al-Saif S, Alvaro R, Manfreda J, Kwiatkowski K, Cates D, Qurashi M, Rigatto H
OBJECTIVE: To determine whether inhalation of 0.8% CO(2) in preterm infants decreases the duration and rate of apnea as effectively as or better than theophylline with fewer adverse side effects. STUDY DESIGN: A prospective, randomized, control study of 42 preterm infants of gestational age 27 to 32 weeks assigned to receive inhaled CO(2) (n = 21) or theophylline (n = 21). The study group had a mean (+/- standard error of the mean) birth weight of 1437 +/- 57 g, gestational age of 29.4 +/- 0.3 weeks, and postnatal age of 43 +/- 4 days. After a control period, 0.8% CO(2) or theophylline was given for 2 hours, followed by a recovery period. RESULTS: In the CO(2) group, apneic time and rate decreased significantly, from 9.4 +/- 1.6 seconds/minute and 94 +/- 15 apneic episodes/hour to 3.0 +/- 0.5 seconds/minute and 34 +/- 5 apneic episodes/hour. In the theophylline group, apneic time and rate decreased significantly, from 8 +/- 1 seconds/minute and 80 +/- 8 apneic episodes/hour to 2.5 +/- 0.4 seconds/minute and 28 +/- 3 apneic episodes/hour. Cerebral blood flow velocity (CBFV) decreased only during theophylline administration. CONCLUSIONS: Our findings suggest that inhaled low (0.8%) CO(2) concentrations in preterm infants is at least as effective as theophylline in decreasing the duration and number of apneic episodes, has fewer side effects, and causes no changes in CBFV. We speculate that CO(2) may be a better treatment for apnea of prematurity than methylxanthines.
Enhancement of basophil apoptosis by olopatadine and theophylline.
Allergy Asthma Proc. 2008 May-Jun; 29(3): 322-8
Kawakami A, Suzukawa M, Koketsu R, Komiya A, Ohta K, Yamamoto K, Yamaguchi M
Regulation of basophil survival is an important aspect in the pathogenesis of allergic inflammation associated with local accumulation of basophils. However, pharmacologic modulation of basophil survival is largely unknown except for the apoptosis-enhancing effect of glucocorticoids. We tested the effects of two anti-allergic and anti-asthmatic drugs, olopatadine and theophylline, on basophil survival. Basophils were highly purified from normal human peripheral blood. Apoptosis was analyzed by flow cytometry using annexin V staining or another staining method that detected alterations in the mitochondrial transmembrane potential. In addition to the conventional method using annexin V, basophil apoptosis was successfully established by analysis of the mitochondrial transmembrane potential. Olopatadine decreased the number of live basophils, and they induced apoptosis of basophils during culture. The decline in live basophils was induced by olopatadine even when low doses of IL-3 were included in the culture medium. Theophylline also affected basophil apoptosis and induced a decrease in the number of live basophils. Basophil apoptosis was enhanced by both olopatadine and theophylline. This effect may partly explain the pharmacologic basis of why these drugs are effective on allergic diseases.
Int J Pharm. 2008 Apr 20;
Shah RB, Bryant A, Collier J, Habib MJ, Khan MA
A simple, sensitive, accurate, and robust stability indicating analytical method is presented for identification, separation, and quantitation of l-thyroxine and eight degradation impurities with an internal standard. The method was used in the presence of commonly used formulation excipients such as butylated hydroxyanisole, povidone, crospovidone, croscarmellose sodium, mannitol, sucrose, acacia, lactose monohydrate, confectionary sugar, microcrystalline cellulose, sodium laurel sulfate, magnesium stearate, talc, and silicon dioxide. The two active thyroid hormones: 3,3',5,5'-tetra-iodo-l-thyronine (l-thyroxine-T4) and 3,3',5-tri-iodo-l-thyronine (T3) and degradation products including di-iodothyronine (T2), thyronine (T0), tyrosine (Tyr), di-iodotyrosine (DIT), mono-iodotyrosine (MIT), 3,3',5,5'-tetra-iodothyroacetic acid (T4AA) and 3,3',5-tri-iodothyroacetic acid (T3AA) were assayed by the current method. The separation of l-thyroxine and eight metabolites along with theophylline (internal standard) was achieved using a C18 column (25 degrees C) with a mobile phase of trifluoroacetic acid (0.1%, v/v, pH 3)-acetonitrile in gradient elution at 0.8ml/min at 223nm. The sample diluent was 0.01M methanolic NaOH. Method was validated according to FDA, USP, and ICH guidelines for inter-day accuracy, precision, and robustness after checking performance with system suitability. Tyr (4.97min), theophylline (9.09min), MIT (9.55min), DIT (11.37min), T0 (11.63min), T2 (14.47min), T3 (16.29min), T4 (17.60min), T3AA (22.71min), and T4AA (24.83min) separated in a single chromatographic run. Linear relationship (r(2)>0.99) was observed between the peak area ratio and the concentrations for all of the compounds within the range of 2-20mug/ml. The total time for analysis, equilibration and recovery was 40min. The method was shown to separate well from commonly employed formulation excipients. Accuracy ranged from 95 to 105% for T4 and 90 to 110% for all other compounds. Precision was
Pediatric liquid medicaments--do they erode the teeth surface? An in vitro study: part I.
J Clin Pediatr Dent. 2008; 32(3): 189-94
Babu KL, Rai K, Hedge AM
The present study was conducted to investigate the endogenous erosive potential of some of the most commonly used pediatric liquid medicaments in our day to day practice. Eight commonly used pediatric liquid medicaments were selected and their endogenous pH was measured using a pH electrode meter Twenty four exfoliated or extracted primary teeth without any carious lesion/restorations, maintained in selected pediatric liquid medicaments were observed under SEM after 1 min, 10 mins and 8 hours of time intervals. The pH ranged between 6.05 (Salbutamol) to 6.77 (Paracetamol) which were acidic, whereas Theophylline had a basic pH of 7.71. The irregular pattern of pit-like erosion area were seen in all specimens, varying from site to site and probably depending on the prismatic versus a prismatic nature and composition of the affected enamel. In conclusion, all the pediatric liquid medicaments used in this study showed an erosive effect on the primary enamel surface irrespective of their pH when viewed under SEM.
Laryngoscope. 2008 May; 118(5): 854-61
Kitahara T, Kubo T, Okumura S, Kitahara M
OBJECTIVE: Meniere's disease is a common inner ear disease with an incidence of 15 to 50 per 100,000 population. Since Meniere's disease is thought to be triggered by an immune insult to the inner ear, we examined intraendolymphatic sac application of steroids as a new therapeutic strategy for intractable Meniere's disease. STUDY DESIGN: Prospective randomized controlled study. METHODS: Between 1996 and 2005, we enrolled and assigned 197 intractable Meniere's patients to three groups in a randomized controlled trial: Group I (G-I)- patients who underwent endolymphatic sac drainage and steroid-instillation; Group II (G-II)-those who underwent endolymphatic sac drainage without steroid-instillation; and Group III (G-III)-those who declined endolymphatic sac drainage. Definitive spells and hearing in all three groups were determined for 2 to 7 years after treatment. RESULTS: According to the 1995 American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) criteria, 2-year results demonstrated that vertigo was completely controlled in 88.0% of patients in G-I (n = 100), 85.1% of patients in G-II (n = 47), and 8.0% in G-III (n = 50). Statistically, G-I = G-II>G-III. Hearing was improved in 49.0% of patients in G-I, 31.9% in G-II, and 6.0% in G-III (G-I>G-II>G-III). Results after 7 years showed that vertigo was completely controlled in 78.8% of patients in G-I, 79.2% in G-II, and 25.0% in G-III (G-I = G-II>G-III). Hearing improved in 36.5% of patients in G-I, 8.3% in G-II, and 0.0% in G-III (G-I>G-II = G-III). CONCLUSIONS: From non-surgical observation in G-III for at least 7 years after treatment, steroids instilled into endolymphatic sac in G-I patients significantly improved hearing in intractable Meniere's patients, more so than endolymphatic sac drainage without steroids in G-II patients.
Arerugi. 2008 May; 57(5): 536-42
Odajima Y, Nakano H, Kato T, Okada K
OBJECTIVE: To examine the causes of sequelae or death of patients who presented them subsequently to seizures that developed during theophylline administration. METHODS: Among 334 patients who had been examined in Study (I), we extracted 56 who had sequelae or died subsequently to the onset of seizures and examined their causes. RESULTS: Many patients had fever at the onset of seizures, many patients had neurologic predispositions prior to seizure onset, and only one patient was found to be free from fever and neurologic findings. At the onset of seizures, most of these patients had blood theophylline concentrations that were within or inferior to the target range (5-15 microg/mL). CONCLUSIONS: We presume it necessary to pay heed to fever and neurologic predispositions in order to prevent sequelae or death that may occur subsequently to seizures that developed during theophylline administration.
Chem Pharm Bull (Tokyo). 2008 Jun; 56(6): 792-5
Bi Y, Zhang Y, Zhao J, Mao S, Hou S
In our previous work, a controlled porosity osmotic pump system with biphasic release of theophylline, a system composed of a tablet-in-tablet (TNT) core and a controlled porosity coating membrane, was developed for the nocturnal therapy of asthma. Sodium phosphate and sodium chloride were selected as the osmotic agents in inner and outer layer of the TNT core respectively, and CA-PEG400-DEP (54.5%-36.4%-9.1%, w/w) was chosen as coating solution. Formulations with weight gain of 19 mg/T (mg per tablet), 9 mg/T and 6 mg/T were prepared respectively and their pharmacokinetics in beagle dogs were also studied to examine the influence of weight gain on their in vivo pharmacokinetics. Sustained release tablet of theophylline (SRT) was selected as reference to evaluate the in vitro and in vivo difference between conventional sustained release tablets and the developed formulation. T(max) and mean residence time (MRT) of the developed formulations were prolonged compared to that of SRT and a satisfying bioavailability was achieved at weight gain of 6 mg/T. If applied to the chronotherapy of asthma at night, the developed formulation with a weight gain of 6 mg/T might help to reduce the inconvenience brought by too later administration of conventional dosage forms and maintain a relatively high blood drug concentration 7 h after administration.
Biochem J. 2008 Jun 3;
Kong H, Jones PP, Koop A, Zhang L, Duff HJ, Chen SR
Caffeine has long been used as a pharmacological probe for studying ryanodine receptor (RyR)-mediated Ca2+ release and cardiac arrhythmias. However, the precise mechanism by which caffeine activates RyRs is elusive. Here we investigated the effects of caffeine on spontaneous Ca2+ release and on the response of single cardiac RyR (RyR2) channels to luminal or cytosolic Ca2+. We found that HEK293 cells expressing RyR2 displayed partial or "quantal" Ca2+ release in response to repetitive additions of submaximal concentrations of caffeine. This quantal Ca2+ release was abolished by ryanodine. Monitoring of endoplasmic reticulum luminal Ca2+ revealed that caffeine reduced the luminal Ca2+ threshold at which spontaneous Ca2+ release occurs. Interestingly, spontaneous Ca2+ release in the form of Ca2+ oscillations persisted in the presence of 10 mM caffeine, and was diminished by ryanodine, demonstrating that unlike ryanodine, caffeine, even at high concentrations, does not hold the channel open. At the single channel level, caffeine markedly reduced the threshold for luminal Ca2+ activation, but had little effect on the threshold for cytosolic Ca2+ activation, indicating that the major action of caffeine is to reduce the luminal, but not the cytosolic, Ca2+ activation threshold. Furthermore, as with caffeine, the clinically relevant, pro-arrhythmic methylxanthines aminophylline and theophylline potentiated luminal Ca2+ activation of RyR2, and increased the propensity for spontaneous Ca2+ release, mimicking the effects of diseased-linked RyR2 mutations. Collectively, our results demonstrate that caffeine triggers Ca2+ release by reducing the threshold for luminal Ca2+ activation of RyR2, and suggest that disease-linked RyR2 mutations and RyR2-interacting pro-arrhythmic agents may share the same arrhythmogenic mechanism.