Prescribing safely in elderly psychiatric wards: survey of possible drug interactions

Potential drug-drug interactions and associated factors among admitted patients with psychiatric disorders at selected hospitals in Northwest Ethiopia

BACKGROUND

Prescribing medications without potential drug-drug interactions (pDDIs) is one of the components of the rational use of medications. However, taking combined medications has resulted in life-threatening pDDIs, which are causing severe clinical outcomes for patients. This study was aimed at assessing the prevalence of pDDIs and associated factors in admitted patients with psychiatric disorders.

METHODS

An institution-based multicenter cross-sectional study was conducted among patients with psychiatric disorders admitted to a selected hospital in Northwest Ethiopia. Samples were approached through a systematic sampling method. The Statistical Package for the Social Sciences (SPSS) version 26 was used to analyze the data. Logistic regression was applied to determine the association of variables with pDDIs. A p-value of < 0.05 was statistically significant.

RESULTS

Out of 325 study participants, more than half (52.9%) were females, with a median age of 61 years. Overall, more than two-thirds (68.9%) were exposed to at least one clinically significant, either significant or serious level of pDDIs. Nearly one-fourth (23.2%) of participants had at least one serious level of pDDIs. Older patients were found more likely to have pDDIs compared to younger patients (p = 0.043). Similarly, patients with a higher number of prescribed medications (p = 0.035) and patients with longer hospital admissions (p = 0.004) were found more likely to be exposed to pDDIs than their counterparts.

CONCLUSION

In this study, a significant number of admitted patients with psychiatric problems encountered clinically significant pDDIs. As a result, healthcare providers could assess and follow patients with a combination of medications that potentially have a drug-drug interaction outcome.

Perpetrators of pharmacokinetic drug-drug interactions arising from altered cytochrome P450 activity: a criteria-based assessment

AIMS

To catalogue the perpetrators of CYP-mediated pharmacokinetic drug-drug interactions (PK-DDIs) using clinically relevant criteria, and to compare this with an analogous catalogue.

METHODS

Candidate inhibitors and inducers of CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A ('perpetrators') were evaluated using published clinical pharmacokinetic interaction studies. Studies were selected on the basis of ≥six human subjects, use of a validated in vivo probe substrate for the CYP enzyme, and clinically relevant dosing. Inhibitors were described according to the FDA classifications of strong, moderate or weak, whereas inducers were classified as major (≥twofold decrease in AUC) or weak (<twofold decrease in AUC). A catalogue of major perpetrators was constructed based on twofold changes in the clearance of probe substrates. Perpetrators in the clinical version of the Cytochromes P450 Drug Interaction Table (CDIT) were compared with the 'accepted' major perpetrators.

RESULTS

From a list of 216 candidate drugs (349 CYP-perpetrator pairs, CYP-PPs), 36 inhibitors and eight inducers were accepted as major perpetrators of PK-DDIs, resulting in 58 CYP-PPs. In comparison, the clinical version of the CDIT had a sensitivity of 33% and a positive predictive value of 68%. One hundred and ninety-nine CYP-PPs were rejected as major perpetrators, and 92 CYP-PPs had insufficient published human pharmacokinetic data for robust classification.

CONCLUSIONS

Using a criteria-based assessment, the number of drugs that are proven or likely major perpetrators of CYP-mediated PK-DDIs is relatively small. Current clinical decision support on PK-DDIs is inconsistent with the published evidence and can be improved using simple criteria.

'Bipolar disorder' in the elderly: what's in a name?

Bipolar disorder is a chronic disorder of mood which leads to episodes of either elevated mood or depression in a sizable number of adults in the community (1%). Though the prevalence rates in the elderly are lower in the community (up to 0.1%), there is significantly higher morbidity in protected environments like care homes and hospital settings where prevalence rates may be as high as 10%. Bipolar disorder in the elderly is probably heterogenous and its etiopathogenesis is complex. Bipolar disorder may be divided into two distinct subtypes, the late onset bipolar (LOB) and the early onset bipolar (EOB) groups. LOB patients tend to have a milder illness in terms of manic severity but they have higher medical and neurological burden. They also have lower familial burden of bipolar illness as compared to EOB patients. There is an increased risk of dementia and stroke in patients with late life bipolar disorder (and there may be a protective effect of lithium in preventing dementia). White matter changes, as seen by increased white matter hyperintensities on neuroimaging, are also increased, providing further evidence of cerebrovascular disease. Treatment of late life bipolar is currently based on guidelines drawn up for younger bipolar disorder patients. Good quality intervention studies are needed to estimate the possible protective effect of cognitive enhancers and/or vascular prevention strategies. This review suggests that late life bipolar disorder, particularly late onset bipolar disorder, is probably a distinct diagnostic entity compared to the younger bipolar patients as it has a different presentation, etiology and hence perhaps needs different treatment strategies.