Dexamethasone half life

Docetaxel, another taxane, binds to tubulin to promote microtubule assembly. The pharmacokinetics of docetaxel are best described by a three-compartment model, with an a half-life of 0.08 hours, a 3 half-life of 1.6 to 1.8 hours, and a terminal half-life of 65 to 73 hours.14 Docetaxel has activity in the treatment of breast, non-small cell lung, prostate, bladder, esophageal, stomach, ovary, and head and neck cancers. Dexamethasone, 8 mg twice daily for 3 days starting the day before treatment, is used to prevent the fluid retention syndrome associated with docetaxel and possible hypersensitivity reactions. The fluid... 

Corticosteroids Adjunctive treatment for acute or delayed NAV Dexamethasone 12 mg IV or PO on day 1 8 mg IV or PO daily on days 2-4 2-4 hours biologic half-life of 36-54 hours... 

Lenalidomide, a derivative of thalidomide, was introduced in 2004. Patients with multiple myeloma stage II/III, who have undergone at least one previous treatment can be treated with bortezomib or with lenalidomide in combination with dexamethasone. There is good oral absorptin with peak plasma levels at 0.5-4 hours. Lenalidomide is maily eliminated by the kidneys with a half-life of circa 3-9 hours. Teratogenicity cannot be excluded. Side effects include thrombosis, pulmonary embolus, and hepato-toxicity, as well as bone marrow toxicity resulting in neutropenia and thrombocytopenia. 

Praziquantel is readily absorbed (80% in 24 hours) after oral administration, with serum concentrations being maximal in 1 to 3 hours the drug has a half-life of 0.8 to 1.5 hours. Its bioavailability is reduced by pheny-toin or carbamazepine and increased by cimetidine. Dexamethasone decreases plasma praziquantel levels by 50%. Praziquantel is excreted by the kidneys. 

Aminoglutethimide also apparently increases the clearance of some steroids. It has been shown to enhance the metabolism of dexamethasone, reducing its half-life from 4-5 hours to 2 hours. 

Dexamethasone reduced the clearance of albendazole and increased its half-life plasma concentrations almost doubled (SEDA-22, 450 476). 

VINCA ALKALOIDS - VINBLASTINE, VINCRISTINE 1. ANTIBIOTICS-rifampicin 2. ANTICANCER AND IMMUNOMODULATING DRUGS - dexamethasone 3. ANTIDEPRESSANTS-St John s wort 4. ANTI EPILEPTICS -carbamazepine, phenobarbital, phenytoin 1 of plasma concentrations of vinblastine and vincristine, with risk of inadequate therapeutic response. Reports of 1 AUC by 40% and elimination half life by 35%, and t clearance by 63%, in patients with brain tumours taking vincristine, which could lead to dangerously inadequate therapeutic responses Due to induction of CYP3A4-mediated metabolism Monitor for clinical efficacy, and t dose of vinblastine and vincristine as clinically indicated in the latter case, monitor clinically and radiologically for clinical efficacy in patients with brain tumours and t dose to obtain desired response... 

Corticosteroids administered intravitreally bypass the blood-ocular barrier to achieve therapeutic levels in the eye while minimizing systemic side effects. Initial studies of intravitreal corticosteroids combined dexamethasone and gentamicin in the treatment of inflammation associated with experimentally reduced endophthalmitis.As of late, interest has shifted to triamcinolone acetonide because of the longer half-life in the vitreous and its use in treatment of proliferative vitreoretinopathies. 

Factors contributing to the reduced propensity of some steroids to raise lOP could include their intraocular bioavailability, considerably shorter pharmacokinetic half-life, and greater susceptibility to metabolism as compared with dexamethasone and prednisolone. In addition to the individual steroid s effect on lOP, concentration, frequency, and length of administration may play a role in lOP elevation. 

Itraconazole markedly increases both systemic exposure to dexamethasone and its effects. This interaction has been investigated in a randomized, double-blind, placebo-controlled, crossover study (94). Eight healthy volunteers took either oral itraconazole 200 mg od or placebo for 4 days. On day 4, each subject was given oral dexamethasone 4.5 mg or intravenous dexamethasone sodium phosphate 5.0 mg. Itraconazole reduced the systemic clearance of intravenous dexamethasone by 68%, and increased its AUC and prolonged its half-life more than three-fold the AUC of oral dexamethasone was increased nearly four-fold and its half-life nearly three-fold. Morning plasma cortisol concentrations at 47 and 71 hours after dexamethasone were significantly lower after itraconazole than placebo. 

Synthetic glucocorticoids The mechanism of action of these agents is identical to that of cortisol. A large number are available for use prednisone and its active metabolite, prednisolone, dexamethasone, and triamcinolone are representative. Their properties (when compared to cortisol) include longer half-life and duration of action, reduced salt-retaining effect, and better penetration of lipid barriers for topical activity (Table 39-1). 

Aminoglutethimide 500 to 750 mg daily reduced the half-life of dexamethasone 1 mg from 264 to 120 minutes in 6 patients. In another 22 patients it was found that larger doses of dexamethasone (1.5 to 3 mg daily) compensated for the increased dexamethasone metabolism caused by aminoglutethimide and complete adrenal suppression was achieved over a prolonged period. Another study found a fourfold increase in dexamethasone clearance in 10 patients taking aminoglutethimide 1 g daily. ... 

A study in 8 healthy subjects found that itraconazole 200 mg daily for 4 days increased the AUC, peak plasma level, and elimination half-life of a single 4.5-mg dose of dexamethasone by 3.7-, 1.7-, and 2.8-fold, respectively. In another phase of the study itraconazole decreased the systemic clearance of intravenous dexamethasone 5 mg by 68% and increased the AUC and elimination half-life 3.3- and 3.2-fold, respectively. The adrenal-suppressant effects of dexamethasone were enhanced by itraconazole. ... 

Nine asthmatic patients had a 40% increase in the clearance and a similar reduction in the half-life of dexamethasone when they were given ephedrine 100 mg daily for 3 weeks. This would be expected to reduce the overall effects of dexamethasone, hut this requires confirmation. Be alert... 

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