Short-term metabolic effects of prednisone administration in healthy subjects

AIMS

Supraphysiologic glucocorticoid activity is well established to cause impaired glucose tolerance and insulin resistance, yet no study has evaluated dose-dependent effects of low-dose prednisone during short-term oral administration.

METHODS

The objective of this study was to quantify the effects of daily 10 or 25 mg prednisone administration for one week on insulin sensitivity by employing a two-step hyperinsulinemic euglycemic glucose clamp (Step 1: insulin infusion = 20 mU/m²/min; Step 2: insulin infusion = 80 mU/m²/min) in healthy, lean males. The amount of glucose infused at steady-state to maintain stable blood glucose [90 mg/dl (4.95 mmol/l)] was used to calculate several indices of insulin sensitivity.

RESULTS

During Step 1 of the clamp, whole body glucose disposal (M) was reduced by 35% (p = 0.003) and M/I was reduced by 29% (p = 0.025) for 25 mg prednisone compared to placebo. No appreciable effect of 10 mg prednisone was observed. During Step 2, M was reduced by 33% (p = 0.001) and 15% (p = 0.006) for 25 and 10 mg prednisone compared to placebo; and M/I ratio was reduced by 31% (p < 0.001) and 13% (p = 0.026), respectively. The insulin sensitivity index, Si, calculated as the quotient of augmentation of M/I between Step 1 and 2, was reduced by 35.3% (p < 0.01) and 23.5% (p < 0.05) for 25 and 10 mg prednisone, respectively.

CONCLUSION

Administration of relatively low pharmacological doses of prednisone for one week impaired insulin sensitivity in a dose-dependent manner in healthy males. These observed changes in insulin sensitivity are likely to be clinically relevant, especially in individuals predisposed to develop glucose intolerance.

Adaptation of the WHO guideline for residual DNA in parenteral vaccines produced on continuous cell lines to a limit for oral vaccines

Although there is a WHO guidance for a limit on residual DNA for parenterally administered vaccines produced on continuous cell lines, there is no corresponding guidance for oral vaccines. To help determine an oral limit, we performed a study of Vero cell DNA uptake in rats, in which the relative uptake and persistence of Vero cell DNA administered orally was compared to its uptake when delivered intramuscularly (IM). The results of this study allowed the generation of an empirically derived IM versus oral factor (10(6)) representing the relative inefficiency of DNA uptake by oral administration. This factor was then applied to the WHO recommended parenteral limit of 10 ng/dose to determine a corresponding upper limit on the level of residual Vero cell DNA for an oral vaccine of 10 mg. As a conservative approach, this empirically determined limit was reduced 100-fold to 100 microg. Thus, the results of this animal study, together with additional evidence in the literature, support a residual DNA safety limit of 100 microg per dose for an oral vaccine produced on a continuous cell line.

In vitro activity of ertapenem against common clinical isolates in relation to human pharmacokinetics

The in vitro activity of ertapenem against bacterial pathogens isolated from patients with moderate to severe complicated intra-abdominal, complicated skin/skin structure, acute pelvic, or complicated urinary tract infection or community acquired pneumonia was compared to ceftriaxone and piperacillin-tazobactam and related to known plasma concentrations of the three agents. Ertapenem was more potent against methicillin-susceptible Staphylococcus aureus (MSSA) than ceftriaxone and piperacillin-tazobactam and was more potent and more active than both of these agents against Enterobacteriaceae and anaerobes. Piperacillin-tazobactam was the most active agent against enterococci and Pseudomonas aeruginosa. All isolates of Enterobacteriaceae (n=1088), Streptococcus pyogenes (n=37), Streptococcus agalactiae (n=48), MSSA (n=187), Haemophilus influenzae (n=59), and Moraxella catarrhalis (n=9) were susceptible to ertapenem; < 1% of 1284 anaerobes and only 1 of 113 Streptococcus pneumoniae (a penicillin-resistant isolate) were resistant to ertapenem. The MIC value at which 90% of all Enterobacteriaceae, streptococci, MSSA, H. influenzae, M. catarrhalis, and anaerobes were inhibited (MIC90) was < or = 1 microg/ml and below the mean plasma concentration of total ertapenem following a 1 g intravenous infusion for at least 24 hours, i.e., the entire recommended dosing interval, and below the free drug concentration for at least 8 h.

P53+/- hemizygous knockout mouse: overview of available data

The performance of the p53-/- transgenic (knockout) mouse model was evaluated through review of the data from 31 short-term carcinogenicity studies with 21 compounds tested as part of the International Life Sciences Institute's (ILSI) Alternatives to Carcinogenicity Testing (ACT) project, together with data from other studies which used comparable protocols. As expected based on the hypothesis for the model, a significant number (12/16 or 75%) of the genotoxic human and/or rodent carcinogens tested were positive and the positive control, p-cresidine, gave reproducible responses across laboratories (18/19 studies positive in bladder). An immunosuppressive human carcinogen, cyclosporin A, was positive for lymphomas but produced a similar response in wild type mice. Two hormones that are human tumorigens, diethylstilbestrol and 17beta-estradiol, gave positive and equivocal results, respectively, in the pituitary with p53-deficient mice showing a greater incidence of proliferative lesions than wild type. None of the 22 nongenotoxic rodent carcinogens that have been tested produced a positive response but 2 compounds in this category, chloroform and diethylhexylphthalate, were judged equivocal based on effects in liver and kidney respectively. Four genotoxic noncarcinogens and 6 nongenotoxic, noncarcinogens were also negative. In total (excluding compounds with equivocal results), 42 of 48 compounds or 88% gave results that were concordant with expectations. The technical lessons learned from the ILSI ACT-sponsored testing in the p53+/- model are discussed.

Mapping of hKCa3 to chromosome 1q21 and investigation of linkage of CAG repeat polymorphism to schizophrenia

CAG trinucleotide polymorphisms in the neuronal small conductance calcium-activated potassium channel gene hKCa3 have been reported to be associated with schizophrenia. Attempts to confirm this finding have met with mixed results. We investigated hKCa3 CAG allele lengths in families from the National Institute of Mental Health (NIMH) Schizophrenia Genetics Initiative, by comparing transmission to discordant siblings and parental transmission to affected offspring. Overall, there was no convincing evidence that hKCa3 CAG lengths differ between schizophrenics and controls. We did, however, observe a trend (P = 0.063) toward over-representation of long (> or = 19) CAG repeats in the shorter of the two hKCa3 alleles in schizophrenics. There was no evidence of excessive parental transmission of long CAG repeat alleles to affected offspring. In addition, we re-mapped hKCa3 and found that it resides on chromosome 1q21, in a region which has been linked to familial hemiplegic migraine, but not to schizophrenia. These data provide no significant support for the association of hKCa3 with schizophrenia.