Adsorption of pregnanediol-3 alpha-glucuronide by plastics and glass

Structure-dependent retention of steroid hormones by common laboratory materials

The tendency of steroid molecules to adsorb to various materials, particularly plastics, has been known of for decades but has not received widespread attention in the scientific community, and a modern, systematic study is lacking. This adsorption is an important consideration for researchers working with steroid hormones as it could skew the results of various experiments. Here we show that steroids adsorb to various vessels used in experiments, including microcentrifuge tubes, glass vials, and cell culture plates, in a manner that depends on the steroid's molecular structure and on the type of vessel. The lipophilicity of steroids is a strong predictor of the degree of adsorption, with nearly 50 % of the most lipophilic steroid tested, pregnenolone, retained in a high-adsorbing microcentrifuge tube after one hour incubation of an aqueous pregnenolone solution followed by removal of the aqueous solvent. We also show the effects of other factors such as incubation time, centrifugation, and temperature on adsorption, and show that adsorption can be mostly prevented by the presence of serum proteins in steroid solutions and/or by the use of low-adsorbing tubes.

Comparative Stability of Oral Vitamin K Liquids Stored in Refrigerated Amber Plastic Syringes

Background: Compounded vitamin K oral liquids may be useful in some patient populations, or when an appropriate solid dosage form is not available. While vitamin K oral liquid is typically prepared with sterile water for injection (SWFI), other compounding agents may be more palatable. Objective: To evaluate stability of compounded vitamin K liquids in SWFI, Ora-Sweet, simple syrup, cherry syrup, and SyrPalta stored in amber plastic oral syringes. Methods: Five types of compounded vitamin K liquids were prepared in triplicate-Ora-Sweet, simple syrup, cherry syrup, SyrPalta, and SWFI without flavoring; aliquoted into amber plastic oral syringes; and stored in a laboratory refrigerator (4.9°C to 5.4°C). On study days, 3 syringes from each batch were removed, diluted to assay concentration, and compared with a freshly prepared US Pharmacopeia reference solution. The samples and reference were analyzed using a previously validated high-performance liquid chromatography-ultraviolet method. Product stability was defined as 90% to 110% labeled amount. Results were further compared using a 2-way ANOVA (analysis of variance; P = .05) with post hoc Tukey's correction for multiple comparisons. Results: Vitamin K in SWFI, SyrPalta, and cherry syrup was stable for 21 days, 7 days, and 24 hours, respectively, under refrigeration in amber plastic oral syringes. Vitamin K in Ora-Sweet and simple syrup demonstrated high within-day variability and low potency. Statistically significant differences were detected between the SWFI formulation and all other vehicles. Conclusion: Vitamin K in SWFI is appropriate for longer-term storage of unit-dosed vitamin K; however, SyrPalta and cherry syrup may be used for short-term storage or immediate administration of vitamin K.

Stability of compounded trilostane suspension in cod liver oil

Trilostane is a synthetic steroid analog used to treat canine hyperadrenocorticism. For small dogs, the dose found in commercially available dosage forms of trilostane is sometimes too high. Compounding trilostane in a liquid diluent provides an option for more precise dosing and adjustments, and can be easier to administer, versus a tablet or capsule. Trilostane suspends well in cod liver oil, which is generally palatable to dogs. The stability of a compounded trilostane suspension in cod liver oil stored at room temperature was investigated for 90 days. Compounded trilostane retained stability, defined as maintaining 90-105% labeled value, for 60 days when stored in amber glass bottles. However, drug potency fell >10% below the labeled value when stored in amber plastic bottles after 7 days.

Challenges and benefits of endogenous steroid analysis by LC–MS/MS

Quantification of endogenous hormonal steroids and their precursors is essential for diagnosing a wide range of endocrine disorders. Historically, these analyses have been carried out using immunoassay, but such methods are problematic, especially for low-concentration analytes, due to assay interference by other endogenous steroids. MS offers improved specificity over immunoassay and can be highly sensitive. GC–MS, with use of stable isotopically labeled internal standards, is considered the ‘gold standard’ method for serum steroid analysis. GC–MS is the method of choice for profiling steroid metabolites in urine, but these techniques are not appropriate for routine use in clinical laboratories owing to a need for extensive sample preparation, as well as analytical expertise. LC–MS/MS compares well to GC–MS in terms of accuracy, precision and sensitivity, but allows simplified sample preparation. While most publications have featured only one or a limited number of steroids, we consider that steroid paneling (which we propose as the preferred term for multitargeted steroid analysis) has great potential to enable clinicians to make a definitive diagnosis. It is adaptable for use in a number of matrices, including serum, saliva and dried blood spots. However, LC–MS/MS-based steroid analysis is not straightforward, and understanding the chemical and analytical processes involved is essential for implementation of a robust clinical service. This article discusses specific challenges in the measurement of endogenous steroids using LC–MS/MS, and provides examples of the benefits it offers.