Elucidation of the pharmacokinetic (PK) properties of new drug candidates and understanding of the PK/pharmacodynamic (PD) relationship is a crucial part of the drug development. The power of an established PK-PD model is highly dependent on the data provided for modeling and thus requires clearly defined high quality bioanalytical data. Bioanalysis of therapeutic proteins is challenged by the potential presence of binding partners such as soluble targets, shedded receptors or the presence of anti-drug antibodies (ADA). As a result, the drug could be present in a sample in a complexed and thus neutralized form. Dependent on the required information, a bioanalytical strategy which clearly differentiates between the different drug forms might be required. From a bioanalytical perspective, these binding partners could be considered as potential “interferences”. Appropriate “interference-free” methods are required to generate correct “total drug” information. However, since free/active drug exposure is considered to be the most relevant information allowing for a meaningful understanding and interpretation of PK and PD data, active drug assays become increasingly important. In this case, the complex formation of drug and binding partners need to be considered during method development and poses specific technological obstacles. Consequently, the definition of the bioanalytical strategy requires a clear understanding of what form of the drug (e.g. free/active, total) needs to be monitored under careful consideration of the drug format and dose, the disease biology and its mode of action. The increasing complexity and potency of modern therapeutic proteins, e.g. multi-domain biologics, goes along with increasing challenges and requirements for the field of bioanalytical sciences. In this presentation, the aspects, which are important for the definition of the bioanalytical strategy and for technology selection (ligand binding assay or mass spectrometry based methods) will be discussed as well as the bioanalytical challenges of correct free/active and total drug quantification. Concepts to identify potential method limitations for appropriate method development and validation will be presented and illustrated by case examples.

Elucidation of the pharmacokinetic (PK) properties of new drug candidates and understanding of the PK/pharmacodynamic (PD) relationship is a crucial part of the drug development. The power of an established PK-PD model is highly dependent on the data provided for modeling and thus requires clearly defined high quality bioanalytical data. Bioanalysis of therapeutic proteins is challenged by the potential presence of binding partners such as soluble targets, shedded receptors or the presence of anti-drug antibodies (ADA). As a result, the drug could be present in a sample in a complexed and thus neutralized form. Dependent on the required information, a bioanalytical strategy which clearly differentiates between the different drug forms might be required. From a bioanalytical perspective, these binding partners could be considered as potential “interferences”. Appropriate “interference-free” methods are required to generate correct “total drug” information. However, since free/active drug exposure is considered to be the most relevant information allowing for a meaningful understanding and interpretation of PK and PD data, active drug assays become increasingly important. In this case, the complex formation of drug and binding partners need to be considered during method development and poses specific technological obstacles. Consequently, the definition of the bioanalytical strategy requires a clear understanding of what form of the drug (e.g. free/active, total) needs to be monitored under careful consideration of the drug format and dose, the disease biology and its mode of action. The increasing complexity and potency of modern therapeutic proteins, e.g. multi-domain biologics, goes along with increasing challenges and requirements for the field of bioanalytical sciences. In this presentation, the aspects, which are important for the definition of the bioanalytical strategy and for technology selection (ligand binding assay or mass spectrometry based methods) will be discussed as well as the bioanalytical challenges of correct free/active and total drug quantification. Concepts to identify potential method limitations for appropriate method development and validation will be presented and illustrated by case examples.

Elucidation of the pharmacokinetic (PK) properties of new drug candidates and understanding of the PK/pharmacodynamic (PD) relationship is a crucial part of the drug development. The power of an established PK-PD model is highly dependent on the data provided for modeling and thus requires clearly defined high quality bioanalytical data. Bioanalysis of therapeutic proteins is challenged by the potential presence of binding partners such as soluble targets, shedded receptors or the presence of anti-drug antibodies (ADA). As a result, the drug could be present in a sample in a complexed and thus neutralized form. Dependent on the required information, a bioanalytical strategy which clearly differentiates between the different drug forms might be required. From a bioanalytical perspective, these binding partners could be considered as potential “interferences”. Appropriate “interference-free” methods are required to generate correct “total drug” information. However, since free/active drug exposure is considered to be the most relevant information allowing for a meaningful understanding and interpretation of PK and PD data, active drug assays become increasingly important. In this case, the complex formation of drug and binding partners need to be considered during method development and poses specific technological obstacles. Consequently, the definition of the bioanalytical strategy requires a clear understanding of what form of the drug (e.g. free/active, total) needs to be monitored under careful consideration of the drug format and dose, the disease biology and its mode of action. The increasing complexity and potency of modern therapeutic proteins, e.g. multi-domain biologics, goes along with increasing challenges and requirements for the field of bioanalytical sciences. In this presentation, the aspects, which are important for the definition of the bioanalytical strategy and for technology selection (ligand binding assay or mass spectrometry based methods) will be discussed as well as the bioanalytical challenges of correct free/active and total drug quantification. Concepts to identify potential method limitations for appropriate method development and validation will be presented and illustrated by case examples.

The continuously increasing number of new psychoactive substances (NPS) available on the drugs of abuse market poses a challenge for clinical and forensic toxicologists. These NPS belong to various chemical classes such as synthetic cannabinoids, phenethylamines, opioids, or benzodiazepines. Only very limited data concerning their safety and toxicokinetic properties are available once they appear on the market. Similar to other xenobiotics, NPS undergo absorption, distribution, metabolism, and excretion processes after consumption. Therefore, the inclusion of metabolites in mass spectral libraries is crucial, especially for urine screening purposes [1]. Authentic human samples may represent the gold standard for identification of metabolites but are often not available and clinical studies cannot be performed due to ethical concerns. However, numerous alternative in vitro and in vivo models are available [2-4]. The talk will give an overview on selected models, discuss current studies, and highlight recent developments.

The continuously increasing number of new psychoactive substances (NPS) available on the drugs of abuse market poses a challenge for clinical and forensic toxicologists. These NPS belong to various chemical classes such as synthetic cannabinoids, phenethylamines, opioids, or benzodiazepines. Only very limited data concerning their safety and toxicokinetic properties are available once they appear on the market. Similar to other xenobiotics, NPS undergo absorption, distribution, metabolism, and excretion processes after consumption. Therefore, the inclusion of metabolites in mass spectral libraries is crucial, especially for urine screening purposes [1]. Authentic human samples may represent the gold standard for identification of metabolites but are often not available and clinical studies cannot be performed due to ethical concerns. However, numerous alternative in vitro and in vivo models are available [2-4]. The talk will give an overview on selected models, discuss current studies, and highlight recent developments.

The continuously increasing number of new psychoactive substances (NPS) available on the drugs of abuse market poses a challenge for clinical and forensic toxicologists. These NPS belong to various chemical classes such as synthetic cannabinoids, phenethylamines, opioids, or benzodiazepines. Only very limited data concerning their safety and toxicokinetic properties are available once they appear on the market. Similar to other xenobiotics, NPS undergo absorption, distribution, metabolism, and excretion processes after consumption. Therefore, the inclusion of metabolites in mass spectral libraries is crucial, especially for urine screening purposes [1]. Authentic human samples may represent the gold standard for identification of metabolites but are often not available and clinical studies cannot be performed due to ethical concerns. However, numerous alternative in vitro and in vivo models are available [2-4]. The talk will give an overview on selected models, discuss current studies, and highlight recent developments.

Dried blood spots (DBS) and exhaled breath are two specimens qualifying for being minimally invasive microsamples. Development of bioanalytical technologies has resulted in the possibility of using alternative sampling procedures to venous blood and urine for toxicological investigations. The use of DBS for bioanalytical investigations is well established. The challenge has been to develop a solution for the need of the specimen with a known and exact volume of the dried blood. One approach has been to compensate for the hematocrit value since that is critical for the spreading of blood over the surface of the filter paper. However, another approach has been to use microfluidics to control the size of the blood before sampling. Several such solutions are available. Another obstacle in the field is that capillary finger-prick blood cannot be considered as identical to venous blood. In addition, for measurement of therapeutic drug concentrations serum and plasma are the most used specimens. This problem has been addressed by development of a technique to produce a dried plasma spot by filtering the blood. Exhaled breath carries aerosol particles from the lung that are formed from the airway lining fluid during the normal breathing maneuver. The airway lining fluid in turn gets contaminated by inhaled substances and from components in the circulation. It was originally discovered 10 years ago that an exhaled breath specimen can be used to detect intake of amphetamine. Following this discovery, the exhaled breath has been demonstrated to be useful for detection intake of large number of misused and therapeutic drugs. In recent time an improved device for collecting exhaled aerosol particles has been developed. The easiness of collecting this specimen provides a possibility of sampling at roadside and when studying drug use in society. The technologies and applications will be discussed.

Dried blood spots (DBS) and exhaled breath are two specimens qualifying for being minimally invasive microsamples. Development of bioanalytical technologies has resulted in the possibility of using alternative sampling procedures to venous blood and urine for toxicological investigations. The use of DBS for bioanalytical investigations is well established. The challenge has been to develop a solution for the need of the specimen with a known and exact volume of the dried blood. One approach has been to compensate for the hematocrit value since that is critical for the spreading of blood over the surface of the filter paper. However, another approach has been to use microfluidics to control the size of the blood before sampling. Several such solutions are available. Another obstacle in the field is that capillary finger-prick blood cannot be considered as identical to venous blood. In addition, for measurement of therapeutic drug concentrations serum and plasma are the most used specimens. This problem has been addressed by development of a technique to produce a dried plasma spot by filtering the blood. Exhaled breath carries aerosol particles from the lung that are formed from the airway lining fluid during the normal breathing maneuver. The airway lining fluid in turn gets contaminated by inhaled substances and from components in the circulation. It was originally discovered 10 years ago that an exhaled breath specimen can be used to detect intake of amphetamine. Following this discovery, the exhaled breath has been demonstrated to be useful for detection intake of large number of misused and therapeutic drugs. In recent time an improved device for collecting exhaled aerosol particles has been developed. The easiness of collecting this specimen provides a possibility of sampling at roadside and when studying drug use in society. The technologies and applications will be discussed.

Dried blood spots (DBS) and exhaled breath are two specimens qualifying for being minimally invasive microsamples. Development of bioanalytical technologies has resulted in the possibility of using alternative sampling procedures to venous blood and urine for toxicological investigations. The use of DBS for bioanalytical investigations is well established. The challenge has been to develop a solution for the need of the specimen with a known and exact volume of the dried blood. One approach has been to compensate for the hematocrit value since that is critical for the spreading of blood over the surface of the filter paper. However, another approach has been to use microfluidics to control the size of the blood before sampling. Several such solutions are available. Another obstacle in the field is that capillary finger-prick blood cannot be considered as identical to venous blood. In addition, for measurement of therapeutic drug concentrations serum and plasma are the most used specimens. This problem has been addressed by development of a technique to produce a dried plasma spot by filtering the blood. Exhaled breath carries aerosol particles from the lung that are formed from the airway lining fluid during the normal breathing maneuver. The airway lining fluid in turn gets contaminated by inhaled substances and from components in the circulation. It was originally discovered 10 years ago that an exhaled breath specimen can be used to detect intake of amphetamine. Following this discovery, the exhaled breath has been demonstrated to be useful for detection intake of large number of misused and therapeutic drugs. In recent time an improved device for collecting exhaled aerosol particles has been developed. The easiness of collecting this specimen provides a possibility of sampling at roadside and when studying drug use in society. The technologies and applications will be discussed.