Alternative monitoring of argatroban using plasma-diluted thrombin time.

OBJECTIVE: To report a case of heparin-induced thrombocytopenia (HIT) in a patient with concurrent liver dysfunction and a prolonged baseline activated partial thromboplastin time (aPTT) in whom argatroban therapy was monitored with aPTT and a novel plasma-diluted thrombin assay. CASE SUMMARY: An 80-year-old man with HIT and liver dysfunction was treated with argatroban, which was initiated at a dose of 0.5 µg/kg/min and gradually decreased to 0.09 µg/kg/min. The patient had a mildly prolonged aPTT at baseline (37.5 seconds). He was concurrently monitored with aPTT, per institution protocol, and plasma-diluted thrombin time. Plasma-diluted thrombin times were consistently lower than aPTTs, but mirrored the trend of the aPTTs. Eleven hours after argatroban was stopped, the aPTT remained elevated (53.9 seconds), while the plasma-diluted thrombin time returned to normal range (26.4 seconds). The patient's therapy was transitioned to warfarin and he had a hospital course with no thrombotic or bleeding complications. DISCUSSION: Plasma-diluted thrombin time is a novel laboratory test consisting of 1 part patient plasma diluted with 3 parts normal plasma. Plasma-diluted thrombin time has been shown to blunt the sensitivity of the thrombin time and may be more accurate for drug monitoring. A MEDLINE search revealed 2 studies using the plasma-diluted thrombin time assay. The first study compared aPTT and plasma-diluted thrombin times in blood samples mixed with argatroban, bivalirudin, or lepirudin at 3 different concentrations. Blood samples contained lupus inhibitors, vitamin k deficiency, or normal baseline aPTTs. The aPTT overestimated drug concentrations in all samples with lupus anticoagulant and vitamin k deficiency, while the plasma-diluted thrombin time correctly estimated drug concentrations in nearly all samples. The second study looked at monitoring dabigatran with plasma-diluted thrombin time and found a linear relationship between the plasma-diluted thrombin time and the dabigatran dose-response curve. CONCLUSIONS: Plasma-diluted thrombin time may be an alternative for direct thrombin inhibitor monitoring in patients with elevated aPTT values at baseline. Further randomized control trials are needed to determine its applicability in clinical practice.

Creating learning opportunities for pharmacy students through an observership program.

PURPOSE: The development, implementation, challenges, and future opportunities associated with a pharmacy observership program are described. SUMMARY: In the summer of 2010, the pharmacy observership committee at The Methodist Hospital created a formalized, institution-based pharmacy observership program to introduce first-and second-year pharmacy students to the diverse areas of pharmacy practice. The two-month experience includes opportunities for students to participate in various departmental research projects and to observe the responsibilities of pharmacy staff. Four students have completed the observership program thus far. All observers commented that the program was a valuable introduction to hospital pharmacy. Feedback was obtained from the observers and each preceptor. Limitations of the program include a lack of funding for parking and lodging expenses, a lack of pagers, and a lack of a stipend for the observers. Although there was not an established budget for the program, our perceived costs were approximately $10,000. CONCLUSION: An observership program was established to allow first- and second-year pharmacy students to gain exposure to various aspects of hospital pharmacy outside of a formal internship.