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  • 1
    Electronic Resource
    Electronic Resource
    Sustained Bronchodilation with Isoproterenol Poly(Glycolide-co-Lactide) Microspheres (1993)
    Springer
    Pharmaceutical research 10 (1993), S. 119-125 
    Details
    ISSN: 1573-904X
    Keywords: bronchodilation ; prolonged action ; isoproterenol ; poly(glycolide-co-lactide) microspheres ; rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An animal study was carried out to evaluate the in vivo bronchodilator action of isoproterenol (Iso) from poly(glycolide-co-lactide) (PGL) microspheres. Microspheres with a mean diameter of 4.5 µm and a drug load of 7% were administered intratracheally to Long-Evans rats. The microspheres released about 70% of the incorporated drug in the instillation medium before administration, which provided immediate action, and the remaining 30% was available for sustained release. A total of 120 animals was anesthetized, paralyzed, artificially ventilated, and divided into 15 groups (n = 8): 3 groups each for saline, blank microspheres, free Iso, blank microspheres with free Iso, and microencapsulated Iso. All instillations were made in a volume of 1 ml/kg and the dose of all Iso preparations was 0.1 mg/kg. At 3, 6, or 12 hr after the intratracheal instillation, a serotonin challenge (40 µg/rat) was administered intravenously to constrict the airways. Airway function tests were performed at each time interval on one group of animals by a maximal expiratory flow-volume maneuver. The heart rate in animals receiving Iso formulations was similar to that in the saline control group, indicating minimal systemic effect of the dose administered. The systemic serum levels were below 2 ng/ml in all the groups. Animals receiving encapsulated Iso resisted the serotonin challenge for at least 12 hr after intratracheal instillation, indicating that the drug was still present over this period of time. On the other hand, the serotonin-induced airway constriction observed in the animals receiving blank microspheres, free Iso, or free Iso with blank microspheres was similar to that in saline controls at all time points. The results clearly show that only a small fraction of the free dose is required in sustained-release form for a prolonged pharmacological effect, resulting in a 50- to 100-fold reduction in the total dose administered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018989400517
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The Protein Binding of Phenytoin, Propranolol, Diazepam, and AL01576 (an Aldose Reductase Inhibitor) in Human and Rat Diabetic Serum (1988)
    Springer
    Pharmaceutical research 5 (1988), S. 261-265 
    Details
    ISSN: 1573-904X
    Keywords: protein binding ; diabetes ; streptozotocin-treated rats ; glucosylated albumin ; AL01576 ; phenytoin ; diazepam ; propranolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The extent of serum protein binding of AL01576, phenytoin (DPH), diazepam (DIAZ), and propranolol (PRO) was evaluated in a group of nondiabetic and a group of insulin-dependent diabetic subjects, as well as in streptozotocin-treated rats. Both serum glucose and glucosylated protein levels were elevated in the diabetic patient population (179 and 150% of control values, respectively). The mean free fractions (f p) of AL01576, DPH, and PRO were not statistically different for the two human groups. The DIAZ f p was slightly elevated (P 〈 0.05) in the diabetic patients (mean = 0.016) compared to the control group (mean f p = 0.014). An acute (〈3 days) and chronic (〉20 days) diabetic rodent model was evaluated using Sprague–Dawley rats following streptozotocin administration (60 mg/kg i.p.). Both diabetic rat groups exhibited substantial increases in serum glucose, free fatty acids (FFA), and protein glucosylation compared to controls. The f p of AL01576 was increased in both the acute (mean = 0.248) and the chronic (mean = 0.202) condition compared to controls (mean = 0.163). The f p of DPH was also markedly increased in the acute (mean = 0.348) and the chronic (mean = 0.280) models compared to untreated controls (mean = 0.207). DIAZ and PRO binding was largely unaffected by the streptozotocin treatment. In vitro studies of purified human albumin suggest that a considerable degree of glucosylation would need to be present in diabetic serum before it would effectively alter drug binding. Our data suggest that only minor drug–serum binding changes occur in diabetic patients who are otherwise healthy and whose disease is well controlled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015966402084
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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