Drug formularies: myths-in-formation

Drug formularies are pivotal tools for delineating and directing prescribing to the "drugs of choice." Full realization of their potential has been hampered by insufficient comparative data on drug efficacy/safety and local resources for formulary development. However, misconceptions concerning fundamental formulary concepts pose an even more formidable obstacle. This article identifies statements illustrating formulary misconception a) made by physicians attending Pharmacy and Therapeutics Committee meetings during a three-year period and b) appearing in published sources. The paper highlights basic objectives and operational requirements of an effective formulary, and contrasts this definition with 20 myths and misinformation culled from these two sources. Not only does such misinformation impair formulary development, many critics are so preoccupied with alleged shortcomings that progress in minimizing the real limitations of formularies has been impeded.     

Myelin formation by mouse glia in myelin-deficient rats treated with cyclosporines

Summary Previous attempts to generate myelin in the myelin-deficient rat spinal cord by transplanting mouse glia were not successful. In order to determine whether this result was due to graft rejection or to interspecies mismatch of cellular or molecular components at the axoglial junction, we have repeated the experiment in cyclosporine-treated rats. Our results show that in the immunosuppressed hosts, foetal glial xenografts form an abundance of myelin within the dorsal columns at or near the injection site about two weeks after the operation. In some cases, myelination extends virtually across the entire width of the dorsal columns. Ultrastructurally, the myelin sheaths are normal in all respects, including the presence of the radial component. The lateral edges of the myelin lamellae form typical paranodal axoglial junctions, some displaying periodic transverse bands. We infer that previous mouse to rat xenograft failures reflect host immune response rather than mismatch of heterologous junctional components. We also compared foetal, early post-natal and adult xenografts. Foetal donor cells, containing an abundance of precursors but virtually no mature oligodendrocytes, are more effective than neonatal donor cells in forming myelin, and after adult grafts, we found no myelin formation. Thus, in xenografts, as in allografts, foetal precursor cells are far more suitable than glia from mature donors in generating significant amounts of myelin.     

Acetylcholinesterase inhibition in dementia with Lewy bodies: results of a prospective pilot trial

OBJECTIVE: Dementia with Lewy bodies (DLB) is the second commonest form of dementia. The response to acetylcholinesterase inhibition (AChEI) could be greater in DLB than in Alzheimer's disease (AD) because cholineacetyl-transferase levels are more reduced in the former. This preliminary trial seeks to compare performances in cognitive tasks before and after tacrine administration in DLB and AD subjects. METHODS: Six DLB and 6 AD patients were enrolled in an open, nonrandomized, intervention trial using 80 mg/day tacrine. Patients met ADRDA or DLB consortium criteria for probable diseases. Subjects were matched for Mini Mental State Examination (MMSE) score, age and sex. Mattis Dementia Rating Scale (DRS), Controlled Oral Word Association Test (FAS) and Boston Naming tests were administered at baseline and at 6 months into treatment. RESULTS: AD and DLB groups did not differ in initial mean total DRS scores. In the primary analysis, both groups declined during the course of treatment (-7.3 +/- 4.2 and -16.8 +/- 39.2 DRS points, respectively). Due to the large variability in DLB posttreatment scores, this group was divided post hoc into responders (DLBr) and nonresponders (DLBnr). The DLBr group outperformed the DLBnr group at baseline (p < 0.05) and, notably, in follow-up DRS test scores (p < 0.001). Two-way MANOVA comparing both DLB subgroups with either the entire AD cohort or similarly stratified AD subgroups showed a significant interaction (F = 7.6; p < 0.015), attributed mostly to declines in DLBnr group scores (p < 0.01). Surprisingly, on DRS memory subscale and FAS tests, there were significant improvements in DLBr scores (p < 0.02). A baseline MMSE (or DRS memory) score >/=15 predicted a positive response to tacrine in DLB. Acceleration of parkinsonism occurred in all DLB subjects. CONCLUSION: Results from a primary analysis of the therapeutic effect of 80 mg/day tacrine in DLB and AD were negative. However, post hoc analysis showed that mild to moderate DLB responds favorably to AChEI relative to AD through stabilization of global cognitive decline and improvements in specific cognitive areas. These results could be useful in the planning of a more definitive study.     

Early stage nasopharyngeal carcinoma: radiotherapy dose and time factors in tumor control

OBJECTIVE: To evaluate radiotherapy dose and length of treatment in the control of early stage nasopharyngeal carcinoma (NPC) treated with a combination of external radiotherapy and brachytherapy, MATERIALS & METHODS: We reviewed the records of 133 patients with early stage nasopharyngeal carcinoma (stage I or II, AJC/UICC staging system) who received definitive radiotherapy in Chang Gung Memorial Hospital from 1979 to 1991. The median follow-up time was 7.1 years with a minimum of 2 years. All patients were treated with megavoltage external radiotherapy to the nasopharynx area (63-72 Gy) followed by high dose rate intracavitary brachytherapy (5-16.5 Gy in one to three fractions, spaced 1-2 weeks apart). The median total dose and time of irradiation was 75 Gy (69.8-81.4 Gy) and 11.6 weeks (7.8-20 weeks) respectively. Survival analysis was used to examine the effect of several variables on prognosis. RESULTS: The 5-year rates were 86.4% for local control, 84.7% for disease free survival, 88.5% for actuarial survival and 84.2% for overall survival. The treatment group (combination of time and dose of irradiation) was the most important prognostic factor according to Cox's proportional hazard model. Patients receiving radiation at a total dose of < or = 75 Gy completed in < 12 weeks showed the best prognosis. CONCLUSION: Treatment time and total treatment dose are both important factors in treating early stage NPC. Decreasing the total radiation time to < 12 weeks and not exceeding a radiation dose of 75 Gy gave the best results.      

Phase I trial of tipifarnib in patients with recurrent malignant glioma taking enzyme-inducing antiepileptic drugs: a North American Brain Tumor Consortium Study.

PURPOSE: To determine the maximum-tolerated dose (MTD), toxicities, and clinical effect of tipifarnib, a farnesyltransferase (FTase) inhibitor, in patients with recurrent malignant glioma taking enzyme-inducing antiepileptic drugs (EIAEDs). This study compares the pharmacokinetics and pharmacodynamics of tipifarnib at MTD in patients on and off EIAEDs. PATIENTS AND METHODS: Recurrent malignant glioma patients were treated with tipifarnib using an interpatient dose-escalation scheme. Pharmacokinetics and pharmacodynamics were assessed. RESULTS: Twenty-three assessable patients taking EIAEDs received tipifarnib in escalating doses from 300 to 700 mg bid for 21 of 28 days. The dose-limiting toxicity was rash, and the MTD was 600 mg bid. There were significant differences in pharmacokinetic parameters at 300 mg bid between patients on and not on EIAEDs. When patients on EIAEDs and not on EIAEDs were treated at MTD (600 and 300 mg bid, respectively), the area under the plasma concentration-time curve (AUC)(0-12 hours) was approximately two-fold lower in patients on EIAEDs. Farnesyltransferase inhibition was noted at all tipifarnib dose levels, as measured in peripheral-blood mononuclear cells (PBMC). CONCLUSION: Toxicities and pharmacokinetics differ significantly when comparing patients on or off EIAEDs. EIAEDs significantly decreased the maximum concentration, AUC(0-12 hours), and predose trough concentrations of tipifarnib. Even in the presence of EIAEDs, the levels of tipifarnib were still sufficient to potently inhibit FTase activity in patient PBMCs. The relevance of these important findings to clinical activity will be determined in ongoing studies with larger numbers of patients.     

高速逆流色谱在天然产物分离中的应用——紫杉烷类二萜及二萜生物碱的制备分离

高速逆流色谱是一种新发展起来的无载体的液液分配色谱技术。它利用聚四氟乙烯(PTFE)螺旋管的方向性与高速行星式运动相结合,产生一种独特的流体动力学现象,使互不相溶的两相溶液在螺旋管中充分混合,顺序传递,导致样品中各个组分由于分配系数的差别而有效的分离。本文介绍了国产的高速逆流色谱仪及应用该仪器制备分离云南红豆杉中结构相近的三种紫杉烷类二萜及二萜生物碱。