Safety, pharmacokinetics and pharmacodynamics of the anti-hepcidin Spiegelmer lexaptepid pegol in healthy subjects

Background and Purpose

Anaemia of chronic disease is characterized by impaired erythropoiesis due to functional iron deficiency, often caused by excessive hepcidin. Lexaptepid pegol, a pegylated structured l‐oligoribonucleotide, binds and inactivates hepcidin.

Experimental Approach

We conducted a placebo‐controlled study on the safety, pharmacokinetics and pharmacodynamics of lexaptepid after single and repeated i.v. and s.c. administration to 64 healthy subjects at doses from 0.3 to 4.8 mg·kg⁻¹.

Key Results

After treatment with lexaptepid, serum iron concentration and transferrin increased dose‐dependently. Iron increased from approximately 20 μmol·L⁻¹ at baseline by 67% at 8 h after i.v. infusion of 1.2 mg·kg⁻¹ lexaptepid. The pharmacokinetics showed dose‐proportional increases in peak plasma concentrations and moderately over‐proportional increases in systemic exposure. Lexaptepid had no effect on hepcidin production or anti‐drug antibodies. Treatment with lexaptepid was generally safe and well tolerated, with mild and transient transaminase increases at doses ≥2.4 mg·kg⁻¹ and with local injection site reactions after s.c. but not after i.v. administration.

Conclusions and Implications

Lexaptepid pegol inhibited hepcidin and dose‐dependently raised serum iron and transferrin saturation. The compound is being further developed to treat anaemia of chronic disease.

Commonly used L-amino acid decarboxylase inhibitors block monoamine oxidase activity in the rat

The effects of the peripheral aromatic amino acid decarboxylase (AADC) inhibitors, carbidopa and benserazide, and the central AADC inhibitor, 3-hydroxybenzylhydrazine (NSD-1015) on peripheral and brain monoamine oxidase (MAO) A and B activity were investigated in the rat. In vitro, carbidopa, benserazide and NSD-1015 all potently inhibited hepatic MAO A and B activity (IC(50) 10-50 micro M). In ex vivo studies following systemic drug administration, NSD-1015 (100 mg/kg ip) produced 88% and 96% inhibition of hepatic and striatal MAO A and B activity respectively. Carbidopa (12.5 mg/kg i.p.) and benserazide (50 mg/kg i.p.) had no effect on striatal MAO A activity or hepatic MAO B activity. However, they inhibited striatal MAO B activity by 45 +/- 10% and 36 +/- 10% respectively. In conclusion, carbidopa and benserazide may not only protect L-DOPA from peripheral decarboxylation, but also increase striatal dopamine content through MAO inhibition. NSD-1015 should not be used to investigate the neuromodulatory role of L-DOPA as it potently inhibits rat striatal MAO.

Ionization behaviour and tautomerism-dependent lipophilicity of pyridine-2(1H)-one cardiotonic agents

The acid-base properties of pyridine-2(1H)-one derivatives, analogues of the cardiotonic agent milrinone, were studied by capillary zone electrophoresis (CZE). Electrophoretic mobility and pH data were fitted to equilibrium expressions and apparent dissociation constants (pKa) calculated by non-linear regression. Compared with the ultraviolet (UV) spectrophotometric method and potentiometric titrations, the CZE technique showed advantages, such as rapidity and applicability to compounds that are sparingly soluble in water. Based on the pKa values, intramolecular electronic interactions were assessed. The lipophilicity of a number of derivatives was also examined, by determining their n-octanol/water distribution coefficients over a wide pH range, and found to be significantly affected by 2-pyridone/2-hydroxypyridine tautomerism. As revealed by a comparison between experimental and calculated log P values, electron withdrawing substituents, especially at the C(6) position of 2-pyridone, favour the less polar hydroxypyridine tautomers both in water and octanol. Our results indicate that the positive inotropism of milrinone-related compounds could be explained taking ionization and tautomerism into account.

Pyrrolo[3,2-c]pyridine derivatives as inhibitors of platelet aggregation

A series of pyrrolo[3,2-c]pyridines, isosteres of the antithrombotic drug ticlopidine, has been synthesized and evaluated in vitro for the ability to inhibit aggregation of human platelet-rich plasma induced by adenosin 5'-diphosphate (ADP). Structure-activity relationships showed their antiplatelet effects to be related to the lipophilicity.

Inhibition of monoamine oxidase-B by condensed pyridazines and pyrimidines: effects of lipophilicity and structure-activity relationships

A number of condensed pyridazines and pyrimidines were synthesized and tested for their monoamine oxidase-A (MAO-A) and MAO-B inhibitory activity. Their lipophilicity was examined by measuring partition coefficients and RP-HPLC capacity factors, revealing some peculiar electronic and conformational effects. Further insights were obtained by X-ray crystallography and a thermodynamic study of RP-HPLC retention. Structure-activity relations highlighted the main factors determining both selectivity and inhibitory potency. Thus, while most of the condensed pyridazines were reversible inhibitors of MAO-B with little or no MAO-A effects, the pyrimidine derivatives proved to be reversible and selective MAO-A inhibitors. Substituents on the diazine nucleus modulated enzyme inhibition. A QSAR analysis of X-substituted 3-X-phenyl-5H-indeno[1,2-c]pyridazin-5-ones showed lipophilicity to increase MAO-B and not MAO-A inhibitory activity.