Changes in the defined daily dose; CYP2D6/CYP3A metabolism as an indicator for dose-setting problems

Altered liver metabolism post-wean abolishes efficacy of vitamin D for breast cancer prevention in a mouse model

Young women have increased risk of vitamin D deficiency, which may increase breast cancer incidence. Here, we assessed the anti-cancer efficacy of vitamin D in mouse models of young-onset breast cancer. In never-pregnant mice, vitamin D supplementation increased serum 25(OH)D and hepatic 1,25(OH)2D3, reduced tumor size, and associated with anti-tumor immunity. These anti-tumor effects were not replicated in a mouse model of postpartum breast cancer, where hepatic metabolism of vitamin D was suppressed post-wean, which resulted in deficient serum 25(OH)D and reduced hepatic 1,25(OH)2D3. Treatment with active 1,25(OH)2D3 induced hypercalcemia exclusively in post-wean mice, highlighting metabolic imbalance post-wean. RNAseq revealed suppressed CYP450 expression postpartum. In sum, we provide evidence that vitamin D anti-tumor activity is mediated through immunomodulatory mechanisms and is ineffective in the post-wean window due to altered hepatic metabolism. These findings have implications for suppressed xenobiotic metabolism in postpartum women beyond vitamin D.

Coping with changes in the Defined Daily Dose in a longitudinal drug consumption database

OBJECTIVE

To illustrate the best approach to accurate representation of temporal evolution of drug consumption, when confronted with changes over time in the Defined Daily Dose (DDD) measurement unit.

METHOD

As an example, drug consumption (2001-2005) at the University Hospital Rijeka was expressed with the corresponding DDD in each year; and with the DDD value of the last year of the observation time window. By visual appraisal, results with both methods were compared with the graph of drug consumption trends expressed in physical units (mg, IU, etc.).

RESULTS

Of 20 drugs for which the DDD value has changed in the 5 year period, 5 were used in Rijeka hospital: erythropoietin parenteral, budesonide nasal spray, repaglinide oral, amoxicillin with clavulanic acid parenteral, and fentanyl transdermal. Graphs for individual drugs with the year by year method showed artificial jerks in the years proceeding the year of DDD change. Representation of total hospital consumption did not differ notably with the two methods.

CONCLUSION

Drug consumption data should be calculated with the latest DDD value in the time window. The policy of the World Health Organisation to keep changes to the system of DDD to a minimum should be continued.

Polymorphic cytochrome P450 enzymes and post-marketing drug dosage revisions: clinical relevance to dermatologic therapies

The therapeutic drug resources available to dermatologists have expanded and encompass off-label use of other drugs as well. As these new resources are employed, it is important to remain vigilant of possible drug interactions and toxicities contingent upon inter-individual variability of plasma drug levels. This article reviews the biochemistry of CYP enzymes and the clinical implications of genetic polymorphisms as relating to certain dermatologic drugs. In addition, we discuss the potential clinical function of cutaneous CYP enzymes.

Preventing postmarketing changes in recommended doses and marketing withdrawals

Recent market withdrawals of prescription drug products have brought attention to premarketing safety research. Less known but related to some drug withdrawals are postmarketing dosage changes of newly marketed drugs, including both dosage reductions and increases. These events have serious effects on patients, manufacturers, and regulatory authorities. Most of these harmful events could be avoided by intensive employment of targeted clinical pharmacology investigations to optimize dosage prior to phase III testing and regulatory approval. In this paper, the frequency and implications of postmarketing dosing changes and market withdrawals are considered in light of approaches to preventing them.