Lack of adherence with the analgesic regimen: a significant barrier to effective cancer pain management

PURPOSE

To evaluate oncology outpatients' level of adherence to their analgesic regimen during a 5-week period.

PATIENTS AND METHODS

A random sample of 65 adult oncology outpatients with a Karnofsky performance status score of >or= 50, an average pain intensity score of >or= 2.5, and radiographic evidence of bone metastasis were recruited for this longitudinal study from seven outpatient settings. On a daily basis, patients rated their level of pain intensity and recorded pain medication intake. Adherence rates for opioid analgesics prescribed on an around-the-clock (ATC) and on an as-needed (PRN) basis were calculated on a weekly basis.

RESULTS

Overall adherence rates for ATC opioid analgesics ranged from 84.5% to 90.8% and, for PRN analgesics, from 22.2% to 26.6%. No significant differences over time were found in either of these adherence rates.

CONCLUSION

One factor that seems to contribute to ineffective cancer pain management is poor adherence to the analgesic regimen.

Return of potassium ion channels in regenerated hair cells: possible pathways and the role of intracellular calcium signaling

Recent electrophysiological studies in pigeon have demonstrated that potassium channels are completely functional in regenerated type II hair cells at 21 days post-treatment (PT) with ototoxic doses of streptomycin. The currents return in the order they appear during development. The mixture of ionic currents in a regenerated type II hair cell in a particular region of the neuroepithelium is the same as in its ancestor in that region. The return of currents in regenerated type I hair cells is more complicated. The dominant conductance gKI is not present until after 70 days PT. Before 70 days, the ionic currents in type I hair cells resemble those of regenerated type II hair cells, suggesting that the ionic currents in type II hair cells might be precursors of the ionic currents in regenerated type I hair cells. New data show that at one year PT, the kinetics and drug sensitivity of the dominant K+ conductance in type I hair cells are identical to gKI. Supporting cells, believed to be the precursors of regenerated type II hair cells, have effectively no voltage-gated outward potassium channels, suggesting that regenerated type II hair cells must develop these channels de novo. The next step is to understand the mechanisms by which the potassium channel protein is synthesized, migrates through the cytosol, and is inserted into the plasmalemma of regenerating hair cells. These mechanisms are unknown. We propose that intracellular calcium is involved in this process, as well as in the differentiation, proliferation, and gene regulation of precursor cells fated to become hair cells.

Multiple sites of control of glutathione S-transferase P1-1 in rat liver

Glutathione transferase P1-1, normally very low in adult rat liver, is induced by a single intravenous dose of lead nitrate. In this transient induction, there are at least three sites of regulation or control. These are transcription, post-transcription, and post-translation. The increase in transcription is evident both by nuclear run-off analysis and by measurement of mRNA levels. The other two sites of control were seen in actinomycin D-treated animals in which RNA synthesis was inhibited by over 80%. Treatment with actinomycin D increases the stability of the mRNA and also somehow inhibits the conversion of a glutathione transferase protein to an enzymatically active form. These three sites offer possibilities for the study of mechanisms of control for this interesting enzyme that may play a role in chemical carcinogenesis and in drug resistance.

Carcinogen-induced mdr overexpression is associated with xenobiotic resistance in rat preneoplastic liver nodules and hepatocellular carcinomas

We have previously reported the isolation of a human breast cancer cell line resistant to doxorubicin (adriamycin; AdrR MCF-7 cells) that has also developed the phenotype of multidrug resistance (MDR). MDR in this cell line is associated with increased expression of mdr (P glycoprotein) gene sequences. The development of MDR in AdrR MCF-7 cells is also associated with changes in the expression of several phase I and phase II drug-detoxifying enzymes. These changes are remarkably similar to those associated with development of xenobiotic resistance in rat hyperplastic liver nodules, a well-studied model system of chemical carcinogenesis. Using an mdr-encoded cDNA sequence isolated from AdrR MCF-7 cells, we have examined the expression of mdr sequences in rat livers under a variety of experimental conditions. The expression of mdr increased 3-fold in regenerating liver. It was also elevated (3- to 12-fold) in several different samples of rat hyperplastic nodules and in four of five hepatomas that developed in this system. This suggests that overexpression of mdr, a gene previously associated with resistance to antineoplastic agents, may also be involved in the development of resistance to xenobiotics in rat hyperplastic nodules. In addition, although the acute administration of 2-acetylaminofluorene induced an 8-fold increase in hepatic mdr-encoded RNA, performance of a partial hepatectomy either before or after administration of 2-acetylaminofluorene resulted in a greater than 80-fold increase in mdr gene expression over that in normal untreated livers. This represents an important in vivo model system in which to study the acute regulation of this drug resistance gene.