Repurposing of H1-receptor antagonists (levo)cetirizine, (des)loratadine, and fexofenadine as a case study for systematic analysis of trials on clinicaltrials.gov using semi-automated processes with custom-coded software

To gain a comprehensive overview of the landscape of clinical trials for the H1-receptor antagonists (H1R antagonists) cetirizine, levocetirizine, loratadine, desloratadine, and fexofenadine and their potential use cases in drug repurposing (the use of well-known drugs outside the scope of the original medical indication), we analyzed trials from clincialtrials.gov using novel custom-coded software, which itself is also a key emphasis of this paper. To automate data acquisition from clincialtrials.gov via its API, data processing, and storage, we created custom software by leveraging a variety of open-source tools. Data were stored in a relational database and annotated facilitating a specially adapted web application. Through the data analysis, we identified use cases for repurposing and reviewed backgrounds and results in the scientific literature. Even though we found very few trials with published results for repurpose indications, extended literature research revealed some prominent use cases: Cetirizine seems promising in mitigating infusion-associated reactions and is also more effective than placebo in the treatment of androgenetic alopecia. Loratadine may be beneficial in the prophylaxis of G-CSF-related bone pain. In COVID-19, H1R antagonists may be helpful, but placebo-controlled scientific evidence is needed. For asthma, the effect of H1R antagonists only seems to be secondary by alleviating allergy symptoms. Our novel method to find potential use cases for repurposing of H1R antagonists allows for high automation, reduces human error, and was successful in revealing potential areas of interest. The software could be used for similar research questions and analyses in the future.

OCTN1: A Widely Studied but Still Enigmatic Organic Cation Transporter Linked to Human Pathology and Drug Interactions

The Novel Organic Cation Transporter, OCTN1, is the first member of the OCTN subfamily; it belongs to the wider Solute Carrier family SLC22, which counts many members including cation and anion organic transporters. The tertiary structure has not been resolved for any cation organic transporter. The functional role of OCNT1 is still not well assessed despite the many functional studies so far conducted. The lack of a definitive identification of OCTN1 function can be attributed to the different experimental systems and methodologies adopted for studying each of the proposed ligands. Apart from the contradictory data, the international scientific community agrees on a role of OCTN1 in protecting cells and tissues from oxidative and/or inflammatory damage. Moreover, the involvement of this transporter in drug interactions and delivery has been well clarified, even though the exact profile of the transported/interacting molecules is still somehow confusing. Therefore, OCTN1 continues to be a hot topic in terms of its functional role and structure. This review focuses on the most recent advances on OCTN1 in terms of functional aspects, physiological roles, substrate specificity, drug interactions, tissue expression, and relationships with pathology.

Substrates and Inhibitors of Organic Cation Transporters (OCTs) and Plasma Membrane Monoamine Transporter (PMAT) and Therapeutic Implications

The gene products of the SLC22A gene family (hOCT1, hOCT2, and hOCT3) and of the SLC29A4 gene (hPMAT or hENT4) are all polyspecific organic cation transporters. Human OCTs (including hPMAT) are expressed in peripheral tissues such as small intestine, liver, and kidney involved in the pharmacokinetics of drugs. In the human brain, all four transporters are expressed at the blood-brain barrier (BBB), hOCT2 is additionally expressed in neurons, and hOCT3 and hPMAT in glia. More than 40% of the presently used drugs are organic cations. This chapter lists and discusses all known drugs acting as substrates or inhibitors of these four organic cation transporters, independently of whether the transporter is expressed in the central nervous system (CNS) or in peripheral tissues. Of interest is their involvement in drug absorption, distribution, and excretion as well as potential OCT-associated drug-drug interactions (DDIs), with a focus on drugs that act in the CNS.

Population pharmacokinetics of gabapentin in patients with neuropathic pain: Lack of effect of diabetes or glycaemic control

AIMS

Gabapentin (GBP) is widely used to treat neuropathic pain, including diabetic neuropathic pain. Our objective was to evaluate the role of diabetes and glycaemic control on GBP population pharmacokinetics.

METHODS

A clinical trial was conducted in patients with neuropathic pain (n = 29) due to type 2 diabetes (n = 19) or lumbar/cervical disc herniation (n = 10). All participants were treated with a single oral dose GBP. Blood was sampled up to 24 hours after GBP administration. Data were analysed with a population approach using the stochastic approximation expectation maximization algorithm. Weight, body mass index, sex, biomarkers of renal function and diabetes, and genotypes for the main genetic polymorphisms of SLC22A2 (rs316019) and SLC22A4 (rs1050152), the genes encoding the transporters for organic cations OCT2 and OCTN1, were tested as potential covariates.

RESULTS

GBP drug disposition was described by a 1-compartment model with lag-time, first-order absorption and linear elimination. The total clearance was dependent on estimated glomerular filtration rate. Population estimates (between-subject variability in percentage) for lag time, first-order absorption rate, apparent volume of distribution and total clearance were 0.316 h (10.6%), 1.12 h^-1 (10.7%), 140 L (7.7%) and 14.7 L/h (6.97%), respectively. No significant association was observed with hyperglycaemia, glycated haemoglobin, diabetes diagnosis, age, sex, weight, body mass index, SLC22A2 or SLC22A4 genotypes.

CONCLUSION

This population pharmacokinetics model accurately estimated GBP concentrations in patients with neuropathic pain, using estimated glomerular filtrationrate as a covariate for total clearance. The distribution and excretion processes of GBP were not affected by hyperglycaemia or diabetes.