Evaluation of a pharmacist-managed electrolyte protocol in outpatients on antiarrhythmic medications.

OBJECTIVE: To evaluate the effectiveness of a pharmacist-managed treatment protocol in achieving and maintaining serum potassium level ([K+]) in the desired range. SETTING: Antiarrhythmic Medications Clinic, The Ohio State University Wexner Medical Center, Columbus, Ohio, from 2009 to 2013. PRACTICE DESCRIPTION: Patients are referred for antiarrhythmic monitoring at this pharmacist-run, electrophysiologist-supervised clinic. Each visit includes medication reconciliation for drug interaction identification, patient interview for potential adverse effects or arrhythmia symptoms, patient education, and drug therapy monitoring through ordering and review of objective testing. PRACTICE INNOVATION: In 2009, a novel, pharmacist-managed electrolyte protocol was established for less than ideal [K+] found during antiarrhythmic monitoring. The protocol was intended to standardize and improve practice, versus pre-protocol management through separate electrophysiology offices. The protocol was designed to maintain [K+] of 4.0-5.0 mmol/L, and it used dietary advice and magnesium and potassium supplementation to normalize [K+]. EVALUATION: The performance of the pharmacist-managed electrolyte protocol was evaluated in consecutive patients seen between June 2009 and July 2013 with [K+] less than 4.0 mmol/L. [K+] during initial visit and laboratory tests were scheduled at weekly intervals after intervention until corrected. Maintenance of [K+] was assessed during the next visit to the clinic. Patients whose management involved pre-protocol between October 2008 and May 2009 at the clinic served as controls. RESULTS: One-hundred ninety-one encounters were evaluated from the post-protocol (treatment) group and 41 encounters from the pre-protocol (control) group. Desired [K+] was reached in 161 (84%) post-protocol patient encounters, compared with 21 (49%) in the control group (P < 0.01). Median time to target was 14 days (range, 3-203 days) in the treatment group and 146 days (range, 7-285 days) in the control group (P < 0.01). Of 125 encounters that received follow-up in the treatment group, 75% remained at desired [K+]. CONCLUSION: A pharmacist-managed electrolyte protocol, implemented as part of a comprehensive antiarrhythmic monitoring service, effectively achieves and maintains desired [K+].

Tolerance of Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) Inhibitors in Patients With Self-Reported Statin Intolerance.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors have been shown to lower atherogenic lipid markers in patients with statin intolerance; however, external validity of these findings is unclear in patients with self-reported statin intolerance. OBJECTIVE: The objective of this study was to describe the tolerability of evolocumab and alirocumab in patients with self-reported statin intolerance. Secondary objectives were to describe their efficacy and obtainability. METHODS: A retrospective chart review was completed and included adult patients with self-reported statin intolerance who were prescribed a PCSK9 inhibitor. Patient-reported side effects, laboratory values, and insurance information were collected for assessment of study objectives. RESULTS: During the study period, 55 patients were prescribed PCSK9 inhibitor, 42 started therapy, and 34 had at least 1 follow-up visit. While myalgias occurred in 14.7% (n = 5) of patients, flu-like symptoms in 11.8% (n = 4), and fatigue in 2.9% (n = 1), only 5.9% (n = 2) of prescriptions for PCSK9 inhibitors were discontinued. Low-density lipoprotein cholesterol (LDL-C) was reduced 48.7% (95% confidence interval [CI]: -1.7%-99.1%), and 20 (58.8%) patients achieved a ≥50% reduction in LDL-C. Regarding obtainability, of the 57 prescriptions written, 77.2% (n = 44) required prior authorization and 5.3% (n = 3) were denied by insurance. CONCLUSION: PCSK9 inhibitors were well tolerated in patients with self-reported statin intolerance.

Role of AMP-activated protein kinase on steroid hormone biosynthesis in adrenal NCI-H295R cells.

Regulation of human androgen biosynthesis is poorly understood. However, detailed knowledge is needed to eventually solve disorders with androgen dysbalance. We showed that starvation growth conditions shift steroidogenesis of human adrenal NCI-H295R cells towards androgen production attributable to decreased HSD3B2 expression and activity and increased CYP17A1 phosphorylation and 17,20-lyase activity. Generally, starvation induces stress and energy deprivation that need to be counteracted to maintain proper cell functions. AMP-activated protein kinase (AMPK) is a master energy sensor that regulates cellular energy balance. AMPK regulates steroidogenesis in the gonad. Therefore, we investigated whether AMPK is also a regulator of adrenal steroidogenesis. We hypothesized that starvation uses AMPK signaling to enhance androgen production in NCI-H295R cells. We found that AMPK subunits are expressed in NCI-H295 cells, normal adrenal tissue and human as well as pig ovary cells. Starvation growth conditions decreased phosphorylation, but not activity of AMPK in NCI-H295 cells. In contrast, the AMPK activator 5-aminoimidazole-4-carboxamide (AICAR) increased AMPKα phosphorylation and increased CYP17A1-17,20 lyase activity. Compound C (an AMPK inhibitor), directly inhibited CYP17A1 activities and can therefore not be used for AMPK signaling studies in steroidogenesis. HSD3B2 activity was neither altered by AICAR nor compound C. Starvation did not affect mitochondrial respiratory chain function in NCI-H295R cells suggesting that there is no indirect energy effect on AMPK through this avenue. In summary, starvation-mediated increase of androgen production in NCI-H295 cells does not seem to be mediated by AMPK signaling. But AMPK activation can enhance androgen production through a specific increase in CYP17A1-17,20 lyase activity.

Metformin inhibits human androgen production by regulating steroidogenic enzymes HSD3B2 and CYP17A1 and complex I activity of the respiratory chain.

Metformin is treatment of choice for the metabolic consequences seen in polycystic ovary syndrome for its insulin-sensitizing and androgen-lowering properties. Yet, the mechanism of action remains unclear. Two potential targets for metformin regulating steroid and glucose metabolism are AMP-activated protein kinase (AMPK) signaling and the complex I of the mitochondrial respiratory chain. Androgen biosynthesis requires steroid enzymes 17α-Hydroxylase/17,20 lyase (CYP17A1) and 3ß-hydroxysteroid dehydrogenase type 2 (HSD3B2), which are overexpressed in ovarian cells of polycystic ovary syndrome women. Therefore, we aimed to understand how metformin modulates androgen production using NCI-H295R cells as an established model of steroidogenesis. Similar to in vivo situation, metformin inhibited androgen production in NCI cells by decreasing HSD3B2 expression and CYP17A1 and HSD3B2 activities. The effect of metformin on androgen production was dose dependent and subject to the presence of organic cation transporters, establishing an important role of organic cation transporters for metformin's action. Metformin did not affect AMPK, ERK1/2, or atypical protein kinase C signaling. By contrast, metformin inhibited complex I of the respiratory chain in mitochondria. Similar to metformin, direct inhibition of complex I by rotenone also inhibited HSD3B2 activity. In conclusion, metformin inhibits androgen production by mechanisms targeting HSD3B2 and CYP17-lyase. This regulation involves inhibition of mitochondrial complex I but appears to be independent of AMPK signaling.

Loss of the C terminus of melanocortin receptor 2 (MC2R) results in impaired cell surface expression and ACTH insensitivity.

OBJECTIVE: Mutations in melanocortin receptor 2 (MC2R) and its related melanocortin receptor accessory protein (MRAP) cause familial glucocorticoid deficiency. We identified a novel MC2R mutation, K289fs. This unique mutation in the C terminus of MC2R is located in the intracellular part of the protein for which the exact function is unknown. SETTING: A 6-wk-old boy presented with severe hypoglycemia, unmeasurable cortisol, and grossly elevated ACTH but normal electrolytes. Genetic analysis revealed homozygote K289fs mutation in MC2R. His parents and siblings were heterozygous but phenotypically normal. INTERVENTION AND RESULTS: The role of the C terminus of MC2R was studied in two cell systems. Because the K289fs mutant changes the last eight amino acids of the protein and leads to protein elongation, wild-type MC2R and C-terminally mutated constructs were tested for activity to respond to ACTH in an OS3 cell-based reporter assay. Wild-type and alanine-substituted constructs responded normally to ACTH. By contrast K289fs and M290X had a total loss of activity. Cell surface assays and confocal localization studies revealed that K289fs and M290X receptors were not found at the cell surface, indicating that their transport from the endoplasmic reticulum to the cell membrane is disrupted. Interestingly, coimmunoprecipitation experiments showed no alteration in the interaction of mutant MC2R with MRAP, suggesting that interaction between these two proteins does not guarantee normal localization. CONCLUSIONS: Loss of the C terminus of MC2R impairs cell surface expression and ACTH sensitivity but does not disrupt interaction of MC2R with MRAP. These findings highlight the extreme sensitivity of MC2R to structural disruption.

Impact of differential P450c17 phosphorylation by cAMP stimulation and by starvation conditions on enzyme activities and androgen production in NCI-H295R cells.

CYP17A1 plays a pivotal role in the biosynthesis of androgens in the adrenals and the gonads. Although this enzyme catalyzes two different reactions on one single active site, its specific activities are regulated independently. Although the 17alpha-hydroxylase activity is rather constant and regulated by gene expression, the 17,20-lyase activity varies significantly with the amount of cofactors or by protein phosphorylation. cAMP increases CYP17A1 expression, P450c17 phosphorylation, and androgen production. However, the exact mechanism(s) and the specific regulators of CYP17A1 remain unknown. Therefore, we studied the regulation of adrenal androgen biosynthesis in human adrenal H295R cells focusing on CYP17A1. We analyzed androgen production and P450c17 activities in H295R cells grown under normal and serum-free conditions and/or after stimulation with 8-bromoadenosine-cAMP. H295R cells grown in starvation medium produced more androgens and had decreased HSD3B2 expression and activity but increased P450c17-17,20-lyase activity and serine phosphorylation. Although starvation increased serine phosphorylation of P450c17 specifically, cAMP stimulation enhanced threonine phosphorylation exclusively. Time-course experiments revealed that a short cAMP stimulation augmented threonine phosphorylation of P450c17 but did not increase 17,20-lyase activity. By contrast, long cAMP stimulation increased androgen production through increased P450c17 activities by enhancing CYP17A1 gene expression. We conclude that serum withdrawal shifts steroidogenesis of H295R cells towards androgen production, providing a suitable model for detailed studies of androgen regulation. In addition, our study shows that starvation and cAMP stimulation regulate P450c17 phosphorylation differentially and that an increase in P450c17 phosphorylation does not necessarily lead to enhanced enzyme activity and androgen production.

Role of DNA methylation in the tissue-specific expression of the CYP17A1 gene for steroidogenesis in rodents.

The CYP17A1 gene is the qualitative regulator of steroidogenesis. Depending on the presence or absence of CYP17 activities mineralocorticoids, glucocorticoids or adrenal androgens are produced. The expression of the CYP17A1 gene is tissue as well as species-specific. In contrast to humans, adrenals of rodents do not express the CYP17A1 gene and have therefore no P450c17 enzyme for cortisol production, but produce corticosterone. DNA methylation is involved in the tissue-specific silencing of the CYP17A1 gene in human placental JEG-3 cells. We investigated the role of DNA methylation for the tissue-specific expression of the CYP17A1 gene in rodents. Rats treated with the methyltransferase inhibitor 5-aza-deoxycytidine excreted the cortisol metabolite tetrahydrocortisol in their urine suggesting that treatment induced CYP17 expression and 17alpha-hydroxylase activity through demethylation. Accordingly, bisulfite modification experiments identified a methylated CpG island in the CYP17 promoter in DNA extracted from rat adrenals but not from testes. Both methyltransferase and histone deacetylase inhibitors induced the expression of the CYP17A1 gene in mouse adrenocortical Y1 cells which normally do not express CYP17, indicating that the expression of the mouse CYP17A1 gene is epigenetically controlled. The role of DNA methylation for CYP17 expression was further underlined by the finding that a reporter construct driven by the mouse -1041 bp CYP17 promoter was active in Y1 cells, thus excluding the lack of essential transcription factors for CYP17 expression in these adrenal cells.