Tetracosactide Acetate

Most pharmaceutical peptides are supplied as acetate salts and the relative amount of acetate to peptide in the final product is one quality criterion required by regulatory agencies to approve the product for clinical use. The objective of the present study was to develop a validated LC-MS/MS method that allows the quantitative determination of the acetate content in pharmaceutical peptide preparations and simultaneous monitoring and collection of qualitative and quantitative information on the peptide during manufacture and in the final product. The method uses reversed phase C18-chromatography to elute the acetate ions under acidic conditions, pH 3, followed by post-column infusion of ammonium hydroxide 0.6M, methanolic solution (30:70) at a rate of 0.5mL/hr. The acetate ions were monitored in negative polarity mass spectrometry by pseudo multiple reaction monitoring (pseudo MRM) against 1, 2- 13C labelled acetate, the internal standard used in the method. The method was linear for acetate concentrations between 0.4 and 25μg/mL with a coefficient of determination (r2) equal to 0.9999. The minimum level of detection and minimum level of quantification were at 0.06μg/mL and 0.18μg/mL respectively. Accuracy of the method was judged by determining the acetate content in a commercial product of the peptide pharmaceutical tetracosactide (TCS) and parallel comparison to the amounts determined by a reversed phase HPLC method with detection at a wavelength of 210nm. The amounts determined by the two methods were in agreement with a RSD that was less than 2%. Additional confirmation of method accuracy was determined by spiking the pharmaceutical peptide with varying amounts of acetate. The recoveries ranged on average between 101 and 102% for the spiked amounts. Accuracy was also determined by calculating the percentage relative error of the predicted to actual acetate concentration in quality controls and was determined to be less than 5%. The LC-MS/MS method was precise with an intra- and inter-day RSD of less than 5%. The standard solutions were stable for at least one month when kept frozen at -80°C with no loss in response and an inter-day RSD of less than 5%. The method was applied to quantify the acetate content in the clinically available product of TCS and to simultaneously evaluate the average peptide molecular weight and detect known impurities by switching from negative polarity MRM analysis to positive polarity MS analysis following the elution of the acetate peak. The method reported herein should corroborate quantitative determinations of the acetate content in pharmaceuticals by the traditional compendial HPLC method.

Background: Megestrol acetate (MA) is commonly used to promote weight gain in malnourished elderly patients. Although adrenal insufficiency has been reported as an adverse effect of MA, this association is not well recognized in clinical practice. Case summary: An 80-year-old woman with worsening dyspnea was transferred to our university-affiliated community medical center from an inpatient psychiatric facility, where she was being treated for major depressive disorder with psychotic features. She had undergone a general decline in physical function accompanied by some weight loss and anorexia consistent with failure to thrive and, 1 month earlier, had been started on MA 400 mg/d to stimulate her appetite and improve her nutrition. During hospitalization at our center, the patient's dyspnea worsened and she was transferred to the intensive care unit, where she was intubated. While in the intensive care unit, the patient developed hypotension. Infectious, cardiac, and neurologic causes of hypotension having been ruled out, a cosyntropin stimulation test was performed to rule out adrenal insufficiency. Cortisol levels before, 30 minutes after, and 60 minutes after administration of cosyntropin were 1.6, 7.1, and 9.8 microg/dL, respectively, indicating a suboptimal response. The adrenocorticotropic hormone level was 8 pg/mL (normal, 10-60 pg/mL). Based on these findings suggesting adrenal insufficiency, MA was discontinued and steroid replacement was initiated. The patient's blood pressure normalized and she improved slowly. She was weaned from the ventilator several weeks later and was discharged to a skilled nursing facility. At 2-month follow-up, the patient's strength and respiratory function were improved, and the results of a repeat cosyntropin stimulation test were normal (cortisol response before, 30 minutes after, and 60 minutes after cosyntropin administration: 15.4, 22.6, and 25.2 microg/dL, respectively). The Naranjo score for this case was 7, indicating a probable correlation between MA use and adrenal insufficiency. Conclusions: This case of adrenal insufficiency in an elderly woman was probably related to MA use. Clinicians should be alert to the possibility of this adverse effect when considering use of MA therapy.

The objectives of this study were first to show adrenocortical response to a long-acting adrenocorticotropic hormone preparation (tetracosactide acetate zinc suspension) (ACTH-Z) and its effect on adrenocortical function in beef cows (Experiment 1) and second to apply the ACTH-Z challenge in dairy cows based on cortisol concentrations in milk collected at routine milking (Experiment 2). In Experiment 1, four beef cows in luteal phase were challenged with ACTH-Z, and plasma cortisol concentrations were determined for 48 h after the injection at 30-min to 2-h intervals. A rapid ACTH test was conducted 3 days before and 2 h after the completion of ACTH-Z injection for 48 h to investigate the effect on adrenocortical function. Plasma cortisol concentrations increased significantly 30 min after ACTH-Z injection (p < 0.001), and the high cortisol levels were maintained for approximately 10 h after the injection. In Experiment 2, eight dairy cows were subjected to ACTH-Z challenge 1-2 weeks and 4-5 weeks post-partum. Blood and milk samples were taken at morning and afternoon milking. All the cows showed a significant increase in cortisol concentrations in plasma as well as in skim milk 8 h after ACTH-Z injection 1-2 weeks and 4-5 weeks post-partum (p < 0.001). There was a significant correlation between plasma and skim milk cortisol concentrations 8 h after ACTH-Z challenge (r = 0.74, p < 0.001). The results obtained in this study suggest that elevated levels of plasma cortisol are maintained for approximately 10 h after ACTH-Z treatment without adverse effect on adrenocortical function and a long-acting ACTH-Z challenge based on cortisol concentrations in milk, which were collected at the morning and the afternoon milking, can be a useful tool to monitor adrenocortical function in cows.