Development of a highly efficient extraction technique and specific multiplex assay for measuring antiretroviral drug concentrations in breast milk

Drugs in Human Milk Part 1: Practical and Analytical Considerations in Measuring Drugs and Metabolites in Human Milk

Human milk is a remarkable biofluid that provides essential nutrients and immune protection to newborns. Breastfeeding women consuming medications could pass the drug through their milk to neonates. Drugs can be transferred to human milk by passive diffusion or active transport. The physicochemical properties of the drug largely impact the extent of drug transfer into human milk. A comprehensive understanding of the physiology of human milk formation, composition of milk, mechanisms of drug transfer, and factors influencing drug transfer into human milk is critical for appropriate selection and use of medications in lactating women. Quantification of drugs in the milk is essential for assessing the safety of pharmacotherapy during lactation. This can be achieved by developing specific, sensitive, and reproducible analytical methods using techniques such as liquid chromatography coupled with mass spectrometry. The present review briefly discusses the physiology of human milk formation, composition of human milk, mechanisms of drug transfer into human milk, and factors influencing transfer of drugs from blood to milk. We further expand upon and critically evaluate the existing analytical approaches/assays used for the quantification of drugs in human milk.

Method validation and clinical application for the quantification of lopinavir, efavirenz, and ritonavir in breast milk using liquid chromatography tandem mass spectrometry

A liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been validated for quantification of three antiretroviral drugs (efavirenz [EFV], lopinavir [LPV], and ritonavir [RTV]) from human breast milk. The samples were extracted employing protein precipitation method using methanol as precipitating agent. The supernatant was evaporated and reconstituted before injecting into the chromatograph and separated on a biphenyl column. Calibration curves for the three tested antiretroviral drugs were linear (r ≥ 0.999) over the range examined. The inter- and intra-day coefficients of variation (CV) were ≤15% for efavirenz, lopinavir, and ritonavir. Mean recovery ranged from 96% to 105% and no major matrix effects were observed. This validated LC-MS/MS method was efficiently applied to determine EFV, LPV, and RTV concentrations in breast milk from Human Immunodeficiency Virus (HIV)-positive breastfeeding mothers. This assay requires a simple sample processing method with a short run time, making it well suited for high-throughput routine clinical or research purposes.

Validation and application of a quantitative LC-MS/MS assay for the analysis of first-line anti-tuberculosis drugs, rifabutin and their metabolites in human breast milk

Breast milk is the preferred method of infant nutrition. Breastfeeding infants born to mothers treated for TB may be at risk of drug toxicity through breast milk exposure, or potentially be vulnerable to select for drug resistance with low level drug exposure. Except for isoniazid, the quantification of first-line TB drugs including rifabutin in breast milk has not been previously described and will provide much-needed insight to TB drug exposure in breastfeeding infants. We developed and validated a novel method to quantify several first-line TB drugs and their major metabolites in breast milk. Accuracy and precision were assessed during three consecutive, independent validation batches over a calibration range of 0.300-30.0 µg/mL for isoniazid and ethambutol, 0.150-15.0 µg/mL for acetyl isoniazid, desacetyl rifampicin, rifampicin, and pyrazinamide, 0.0150-1.50 µg/mL for rifabutin, and 0.00751-0.751 µg/mL for deacetyl rifabutin in breast milk. The method was reproducible for all analytes when using breast milk from six different sources and was not influenced by matrix effects with a mean regression precision (CV(%)) ranging between 1.0 and 2.8. The average recovery of analytes from the matrix was 76.7-99.1%, with a CV(%) between 0.4 and 4.4, while the average process efficiency was between 74.4 and 93.1% with a CV(%) between 1.9 and 8.3. Although only acetyl isoniazid, isoniazid, ethambutol, and pyrazinamide were successfully assayed in breast milk, samples taken from mothers treated for rifampicin-resistant TB and the inclusion of all first-line TB drugs, including rifabutin in the assay development and validation process will allow future quantification of these analytes in breast milk.

Validation and clinical application of a novel LC-MS method for quantification of dolutegravir in breast milk

Aim: A novel, sensitive and reproducible method for quantification of dolutegravir (DTG) in dried breast milk spots (DBMS) was developed and validated for use in clinical studies. Its application enabled measurement of DTG pharmacokinetics in breastfeeding mothers and their infants. Results/methodology: Sample extraction was by liquid-liquid extraction using tert-butyl methy-ether, with DTG-d5 as an internal standard. DTG was eluted on a reverse phase C18 Waters XBridge (3.5 μm: 2.1 × 50 mm) column using a gradient mobile phase consisting of 0.1% formic acid in deionised water or methanol. The assay was validated over a calibration range of 10-4000 ng/ml. Conclusion: Stability, inter and intra-assay variability were acceptable according to FDA and EMA bioanalytical method guidelines. The assay is robust, accurate, precise and can be reliably applied for analysis of clinical samples in trials from low resource settings.

Bioanalytical challenge: A review of environmental and pharmaceuticals contaminants in human milk

An overview of bioanalytical methods for the determination of environmental and pharmaceutical contaminants in human milk is presented. The exposure of children to these contaminants through lactation has been widely investigated. The human milk contains diverse proteins, lipids, and carbohydrates and the concentration of these components is drastically altered during the lactation period providing a high degree of an analytical challenge. Sample collection and pretreatment are still considered the Achilles' heel. This review presents liquid chromatographic methods developed in the last 10 years for this complex matrix with focuses in the extraction and quantification steps. Green sample preparation protocols have been emphasized.

Validation and clinical application of a method to quantify nevirapine in dried blood spots and dried breast-milk spots

OBJECTIVES

The validation and clinical application of an LC-MS/MS method for the quantification of nevirapine in dried blood spots (DBS) and dried breast-milk spots (DBMS) are presented.

METHODS

DBS and DBMS were prepared from 50 and 30 μL of nevirapine-spiked whole blood and human breast milk, respectively. Chromatographic separation was achieved on a reverse-phase C18 column with 0.1% formic acid in water/acetonitrile using a solvent gradient programme at a flow rate of 400 μL/min, and detection was by a TSQ Quantum Access triple quadrupole mass spectrometer. The clinical application was evaluated in HIV-positive nursing mothers and their breastfed infants.

RESULTS

The assay was validated over the concentration range 50-10,000 ng/mL. Accuracy ranged from 93.3% to 113.4% and precision ranged from 1.9% to 12.0%. The mean (percentage coefficient of variation) recovery of nevirapine from DBS and DBMS was ≥ 70.7% (≤ 8.2) and the matrix effect was ≤ 1.04 (≤ 6.1). Nevirapine was stable in DBS and DBMS for ≥ 15 months at room temperature and -80°C. Mean (SD) AUC0-12, Cmax and Cmin in maternal plasma versus breast milk were 57,808 ng · h/mL (24,315) versus 55,817 ng · h/mL (22,368), 6140 ng/mL (2605) versus 5231 ng/mL (2215) and 4334 ng/mL (1880) versus 4342 ng/mL (2245), respectively. The milk-to-plasma concentration ratio over the dosing interval was 0.94 (0.15). Infant plasma concentrations 2 and 8 h after maternal dosing were 580.6 ng/mL (464.7-1607) and 584.1 ng/mL (381.5-1570), respectively.

CONCLUSIONS

These methods further extend opportunities for conducting clinical pharmacokinetic studies in nursing mother-infant pairs, especially in resource-limited settings.

Breast milk pharmacokinetics of efavirenz and breastfed infants' exposure in genetically defined subgroups of mother-infant pairs: an observational study

BACKGROUND

The antiretroviral drug efavirenz is widely used during breastfeeding. Evaluating its safety requires an understanding of its breast milk pharmacokinetics, level of breastfed infants' exposure, and potential influence of polymorphisms in drug disposition genes.

METHODS

For this observational study, we investigated plasma and breast milk pharmacokinetics of efavirenz and breastfed infants' exposure in human immunodeficiency virus positive nursing mothers and their breastfed infants. We also evaluated potential variability due to genetic polymorphisms in CYP2B6, NR1I3, CYP2A6, ABCB1, ABCB5, and ABCG2.

RESULTS

CYP2B6 516G>T was independently associated with efavirenz concentrations in maternal plasma, breast milk, and infant plasma (n = 134). When stratified based on CYP2B6 516G>T (n = 29 ; 11 GG, 10 GT and 8 TT), efavirenz pharmacokinetic parameters in plasma and breast milk differed significantly between patient groups. The median time-averaged milk-to-plasma concentration ratio was 1.10 (range: 0.57-1.71). The estimated maximum infant efavirenz dose from breast milk was 809 µg/kg/day (215-2760) and pediatric dose weight-adjusted exposure index was 4.05% (1.08-13.8). Infant plasma concentrations did not change significantly during the dosing interval, 157 ng/mL (28.6-1360) in pooled analysis and 315 ng/mL (108-1360) in CYP2B6 516TT group. Infant plasma concentrations were highest up to 8 days of age at 1590 ng/mL (190-4631) and decreased by about 90% in the age stratum day 9 to 3 months. No efavirenz related toxicity was reported.

CONCLUSIONS

Most breastfed infants are exposed to <10% of the weight-adjusted therapeutic pediatric dose, the safety threshold for exposure to maternal drugs from breast milk.

Development, validation and clinical application of a novel method for the quantification of efavirenz in dried breast milk spots using LC-MS/MS

OBJECTIVES

This manuscript describes the development, validation and clinical application of a novel method for the quantification of the antiretroviral drug efavirenz in dried breast milk spots using LC-MS.

METHODS

Dried breast milk spots were prepared by spotting 30 μL of human breast milk on each circle of Whatman 903 Protein Saver cards. Chromatographic separation was achieved on a reverse-phase C18 column with 1 mM ammonium acetate in water/acetonitrile using a solvent gradient at a flow rate of 400 μL/min and detection was by TSQ Quantum Access triple quadrupole mass spectrometer equipped with a heated electrospray ionization source. The method was applied to characterize the breast milk pharmacokinetic profile of efavirenz in HIV-positive nursing mothers receiving regimens containing 600 mg of efavirenz once daily.

RESULTS

The assay was validated over the concentration range 50-7500 ng/mL. Accuracy ranged between 95.2% and 102.5% and precision ranged between 1.05% and 9.53%. The average recovery of efavirenz from dried breast milk spots was 106.4% and the matrix effect was 8.14%. Stability of efavirenz in dried breast milk spots and processed samples at room temperature, -40°C and -80°C was demonstrated. In the pharmacokinetic study, the mean (SD) AUC0-24, Cmax and Cmin of efavirenz in breast milk were 59,620 ng·h/mL (17,440), 4527 ng/mL (1767) and 1261 ng/mL (755.9), respectively. The mean (range) milk-to-plasma concentration ratio over the dosing interval was 0.78 (0.57-1.26).

CONCLUSIONS

The dried breast milk spot method is simple, robust, accurate and precise, and can be used in settings with limited resources.

Antiretroviral bioanalysis methods of tissues and body biofluids

Research in the many areas of HIV treatment, eradication and prevention has necessitated measurement of antiretroviral (ARV) concentrations in nontraditional specimen types. To determine the knowledgebase of critical details for accurate bioanalysis, a review of the literature was performed and summarized. Bioanalytical assays for 31 ARVs, including metabolites, were identified in 205 publications measuring various tissues and biofluids. 18 and 30% of tissue or biofluid methods, respectively, analyzed more than one specimen type; 35-37% of the tissue or biofluid methods quantitated more than one ARV. 20 and 76% of tissue or biofluid methods, respectively, were used for the analysis of human specimens. HPLC methods with UV detection predominated, but chronologically MS detection began to surpass. 40% of the assays provided complete intra- and inter-assay validation data, but only 9% of publications provided any stability data with even less for the prevalent ARV in treatments.

Good performance of an immunoassay based method for nevirapine measurements in human breast milk

BACKGROUND

Understanding the distribution of antiretro-virals in breastfeeding HIV-positive mothers is essential, both for prevention of mother-to-child HIV transmission and for research on the development of drug resistance. The ARK nevirapine (NVP)-test is an immunoassay method for nevirapine measurements, developed and validated for plasma use. In this study, the ARK NVP-test was evaluated for measurement of nevirapine concentrations in breast milk. High performance liquid chromatography (HPLC) is the method currently used to determine nevirapine in breast milk. This method, however, requires complicated extraction techniques. The ARK method employs an immunoassay technology and requires a small sample volume (40 μL) and no pre-treatment of the samples.

METHODS

Commercial enzyme and antibody were used and calibration standards and quality controls were prepared from pooled breast milk from HIV-uninfected women. Clinical samples from HIV-infected women receiving a single-dose of nevirapine were analyzed.

RESULTS

Precision and accuracy were evaluated with two concentrations of quality control materials analyzed in three replicates on four different days and was <4%, and between 96.5% and 104.6%, respectively. Clinical samples were analyzed and CVs ranged from 0.0% to 11.1%. The median nevirapine concentration in breast milk 1 week post-partum was 0.29 μg/mL (range 0.11-0.90 μg/mL) in women treated with a single-dose of nevirapine.

CONCLUSIONS

The ease of use and small sample volume makes the ARK assay an attractive alternative to HPLC analyses for determinations of nevirapine concentrations in breast milk.

Studies on antiretroviral drug concentrations in breast milk: validation of a liquid chromatography-tandem mass spectrometric method for the determination of 7 anti-human immunodeficiency virus medications

Studying the pharmacokinetics of antiretroviral drugs in breast milk has important implications for the health of both the mother and the infant, particularly in resource-poor countries. Breast milk is a highly complex biological matrix, yet it is necessary to develop and validate methods in this matrix, which simultaneously measure multiple analytes, as women may be taking any number of drug combinations to combat human immunodeficiency virus infection. Here, we report a novel extraction method coupled to high-performance liquid chromatography and tandem mass spectrometry for the accurate, precise, and specific measurement of 7 antiretroviral drugs currently prescribed to infected mothers. Using 200 microL of human breast milk, simultaneous quantification of lamivudine (3TC), stavudine (d4T), zidovudine (ZDV), nevirapine (NVP), nelfinavir (NFV), ritonavir, and lopinavir was validated over the range of 10-10,000 ng/mL. Intraday accuracy and precision for all analytes were 99.3% and 5.0 %, respectively. Interday accuracy and precision were 99.4 % and 7.8%, respectively. Cross-assay validation with UV detection was performed using clinical breast milk samples, and the results of the 2 assays were in good agreement (P = 0.0001, r = 0.97). Breast milk to plasma concentration ratios for the different antiretroviral drugs were determined as follows: 3TC = 2.96, d4T = 1.73, ZDV = 1.17, NVP = 0.82, and NFV = 0.21.

Addition of 7 days of zidovudine plus lamivudine to peripartum single-dose nevirapine effectively reduces nevirapine resistance postpartum in HIV-infected mothers in Malawi

BACKGROUND

We assessed whether 7 days of zidovudine + lamivudine postpartum with single-dose nevirapine at labor decreases nevirapine resistance in HIV-infected women in Malawi.

METHODS

HIV-infected pregnant women receiving intrapartum single-dose nevirapine and 7 days of zidovudine + lamivudine (n = 132) and women receiving intrapartum single-dose nevirapine alone (n = 66) were followed from an antenatal visit through 6 weeks postpartum. Plasma specimens at 2 and 6 weeks postpartum were tested for genotypic resistance to nevirapine by population sequencing and sensitive real-time polymerase chain reaction. Poisson regression was used to determine predictors of postpartum nevirapine resistance.

RESULTS

Median HIV RNA was similar at entry (4.27 log vs. 4.35 log, P = 0.87), differed at 2 weeks postpartum (2.67 log vs. 3.58 log, P < 0.0001) but not at 6 weeks postpartum (4.49 log vs. 4.40 log, P = 0.79), between single-dose nevirapine/zidovudine + lamivudine and single-dose nevirapine groups, respectively. Nevirapine resistance, measured by population sequencing and sensitive real-time polymerase chain reaction, was significantly less common in those receiving single-dose nevirapine/zidovudine + lamivudine compared with single-dose nevirapine, respectively, at 2 weeks [10% (4 of 40) vs. 74% (31 of 42), P < 0.0001] and 6 weeks postpartum [10% (11 of 115) vs. 64% (41 of 64), P < 0.0001; adjusted relative risk = 0.18, 95% confidence interval (0.10 to 0.34)].

CONCLUSIONS

The significant decrease in nevirapine resistance conferred by 1 week of zidovudine + lamivudine should help policymakers optimize peripartum HIV prophylaxis recommendations.

The current role of liquid chromatography-tandem mass spectrometry in therapeutic drug monitoring of immunosuppressant and antiretroviral drugs

Therapeutic drug monitoring of critical dose immunosuppressant drugs is established clinical practice and there are similar good reasons to monitor antiretrovirals. The aim of this article is to review the recent literature (last five years), with particular reference to the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). LC-MS/MS offers many potential advantages. The superior selectivity of LC-MS/MS over immunoassays for immunosuppressant drugs has been widely reported. Simultaneous measurement of a number of drugs can be performed. It is currently routine practice for the four major immunosuppressants (cyclosporin, tacrolimus, sirolimus and everolimus) to be simultaneously measured in whole blood. While up to 17 antiretroviral drugs have been simultaneously measured in plasma. The exquisite sensitivity of LC-MS/MS also provides the opportunity to measure these drugs in alternative matrices, such as dried blood spots, saliva, peripheral blood mononuclear cells and tissue. However, the clinical utility of measuring these classes of drugs in alternative matrices is still to be determined.