Nanostructured lipid carriers loaded with Halobetasol propionate for topical treatment of inflammation: Development, characterization, biopharmaceutical behavior and therapeutic efficacy of gel dosage forms.

The aim of this research was the development and characterization of three gel dosage forms of Halobetasol propionate loaded lipid nanoparticles (HB-NLC) for the treatment of inflammatory skin diseases. A Pluronic gel (Pl-HB-NLC), a Carbopol gel (Cb-HB-NLC) and a Cremigel (Cg-HB-NLC), were characterized for stability, swelling, degradation, porosity and rheology. The biopharmaceutical behavior of in vitro release and ex vivo permeation, along with microbiological stability were also evaluated. Tolerance and therapeutic efficacy were determined in vivo. The gels proved to have eudermic pH and to be effective to improve HB-NLC stability for more than 6 months. In vitro drug release profiles were adjusted to a first order (Pl-HB-NLC, Cg-HB-NLC) and hyperbola (Cb-HB-NLC) kinetic models, revealing sustained drug release. Ex vivo biopharmaceutical behavior showed slow drug penetration through skin, delaying the drug entrance into systemic circulation. The formulations were effective in reducing inflammation with a lower drug dose in comparison with existing treatments, obtaining the fastest effect when using Pl-HB-NLC. After application of the formulations in volunteers, no irritation, redness or edema reactions were detected, plus, an enhancement of the biomechanical properties of the skin was evidenciated. Therefore, the results indicate that these formulations are a suitable alternative to current treatments.

2-Aminomethyl piperidines as novel urotensin-II receptor antagonists.

A series of 2-aminomethyl piperidines has been discovered as novel urotensin-II receptor antagonists. The synthesis, initial structure-activity relationships, and optimization of the initial hit that resulted in the identification of potent, cross-species active, and functional urotensin-II receptor antagonists such as 1a and 11a are described.

Analogues of neurohypophyseal hormones, oxytocin and arginine vasopressin, conformationally restricted in the N-terminal part of the molecule.

It is generally accepted that the conformation of the N-terminal part of neurohypophyseal hormones analogues is important for their pharmacological activity. In this work, we decided to investigate how the substitution of positions 2 and 3 with the ethylene-bridged dipeptide would alter the pharmacological properties of OT, [Mpa1]OT, and [Cpa1]OT (OT=oxytocin; Mpa=3-mercaptopropionic acid; Cpa=1-mercaptocyclohexaneacetic acid) and to investigate how a bulky 3,3-diphenyl-L-alanine residue incorporated in position 2 of AVP, [Mpa1]AVP, and [Cpa1]AVP (AVP=arginine vasopressin) would change the pharmacological profile of the compounds. The next analogues, [Val4]AVP, [Mpa1,Val4]AVP, and [Cpa1,Val4]AVP, had N-benzyl-L-alanine introduced at position 3. The last peptide was designed by Cys1 substitution in AVP by its sterically restricted bulky counterpart, alpha-hydroxymethylcysteine. All the peptides were tested for their in vitro uterotonic, pressor, and antidiuretic activities in the rat. The results of these assays showed that the reduction of conformational freedom of the N-terminal part of the molecule had a significant impact on pharmacological activities.

Influence of enantiomers of 1-naphthylalanine in position 2 of VAVP and dVAVP on their pharmacological properties.

In this study, we described the synthesis and some pharmacological properties of four new analogues of arginine vasopressin (AVP). Two peptides are substituted in position 2 with L-1-naphthylalanine (L-1-Nal) or its D-enantiomer and in position 4 with valine. In the further two compounds, we combined the above modifications with placement into position 1 of 3-mercaptopropionic acid residue (Mpa). All new peptides were tested for vasopressor and antidiuretic activities. We also estimated the uterotonic activities of these compounds in vitro. Urine samples prior and after peptide administration were analyzed for electrolytes excretion. All analogues are potent oxytocin antagonists. One of them, namely [L-1-Nal2,Val4]AVP, which appears practically not to interact with V1a and V2 receptors, is exceptionally selective. Our results open new possibilities for the design of very potent and selective oxytocin antagonists in vitro.

Identification of novel adrenomedullin in mammals: a potent cardiovascular and renal regulator.

We have identified cDNA encoding a new member of the adrenomedullin (AM) family, AM2, for the first time in mammals (mouse, rat and human). The predicted precursor carried mature AM2 in the C-terminus, which had an intramolecular ring formed by an S-S bond and a possibly amidated C-terminus. Phylogenetic analyses clustered AM2 and AM into two distinct but closely related groups. Similarity of exon-intron structure and synteny of neighboring genes showed that mammalian AM2 is an ortholog of pufferfish AM2 and a paralog of mammalian AM. AM2 mRNA was expressed in submaxillary gland, kidney, stomach, ovary, lymphoid tissues and pancreas of mice, but not in adrenal and testis. Intravenous injection of synthetic mature AM2 decreased arterial pressure more potently than AM, and induced antidiuresis and antinatriuresis in mice. These results show that at least two peptides, AM and AM2, comprise an adrenomedullin family in mammals, and that AM2 may play pivotal roles in cardiovascular and body fluid regulation.

Nonsteroidal cardiotonics. 2. The inotropic activity of linear, tricyclic 5-6-5 fused heterocycles.

We previously reported the structure-activity relationships (SAR) of adibendan (1), a potent and long-acting cardiotonic. This paper describes the synthesis of a novel series of linear, tricyclic fused heterocycles of the 5-6-5 type. The compounds were evaluated for positive inotropic activity in anesthetized rats, cats, and dogs. Changes in left ventricular dP/dt were measured as an index of cardiac contractility. The increase in contractility was not mediated via stimulation of beta-adrenergic receptors. The data revealed the intrinsic positive inotropic activity of the parent compound of this series, 5,7-dihydro-7,7-dimethylpyrrolo[2,3-f]benzimidazol-6(1H)-one (2). The structural features that impart optimal inotropic activity are presented and compared with those of the 4,5-dihydro-3(2H)-pyridazinone series. The most potent compounds were evaluated orally in conscious dogs with implanted Konigsberg pressure transducers to measure ventricular pressures, and their effect on left ventricular dP/dt was compared with that of 1, pimobendan, and indolidan. After administration of 1 mg/kg, 1, 3, 7, 19, 22, 24, 31, 54, pimobendan, and indolidan were equipotent, but only with 1, 31, pimobendan, and indolidan, durations of action exceeded 6 h.

alpha-Adrenergic agents. 2. Synthesis and alpha 1-agonist activity of 2-aminotetralins.

Substituted 2-aminotetralins are potent, selective, direct-acting agonists at postjunctional alpha 1 receptors. Within this series, substituent alterations on the ring, as well as on the nitrogen, change the potency of compounds by over three orders of magnitude (EC50 = 12 to greater than 10 000 nM). It has been demonstrated experimentally that substitution at both the 5 and 8 positions of the aromatic ring produces optimum agonist potency. Removal of either substituent results in a loss of potency and efficacy relative to norepinephrine. Substitution at positions 6 and/or 7 is generally detrimental to activity. Methyl, ethyl, or dimethyl substitution on nitrogen is compatible with high agonist potency, while substitution with larger groups is not. The most potent agonist in this series is 5-(thiomethyl)-8-methoxy-2-aminotetralin, which has an EC50 of 12 nM.

Novel cyclic analogs of angiotensin II with cyclization between positions 5 and 7: conformational and biological implications.

To study the conformational features of molecular recognition of angiotensin II (Asp1-Arg2-Val3-Tyr4-Val/IIe5-His6-Pro7-Phe8, AII), the synthesis and biological testing of several cyclic analogs of AII cyclized between positions 5 and 7 have been performed. The synthesized analogs were Sar1-Arg2-Val3-Tyr4-cyclo(Cys5-His6-Pen7)-Phe8 (3), Sar1-Arg2-Val3-Tyr4-cyclo(Asp5-His6-Apt7)-Phe8 (4), Sar1-Arg2-Val3-Tyr4-cyclo(Glu5-His6-Apt7)-Phe8 (5), Sar1-Arg2-Val3-Tyr4-cyclo-(Cys5-His6-Mpt7)-Phe8 (6), Sar1-Arg2-Val3-Tyr4-cyclo(Cys5-His6-Mpc7)-Phe8 (7), Sar1-Arg2-Val3-Tyr4-cyclo(Hcy5-His6-Mpt7)-Phe8 (8), and Sar1-Arg2-Val3-Tyr4-cyclo(Hcy5-His6-Mpc7)-Phe8 (9), where Apt stands for 4-amino-trans-proline, and Mpt and Mpc for 4-mercapto-trans- and -cis-prolines, respectively. Compound (9) showed good affinity at AT-1 receptors, namely a KD = 20 nM. In functional assays, it showed the characteristics of a weak partial agonist with a relative affinity of 0.26% of that for AII and an intrinsic efficacy, alpha E, of 0.42. Molecular modeling suggested a possible explanation for this finding: the relatively strong binding and the weak partial agonistic activity of compound 9 are due to interaction with AT-1 receptor of only two functionally important groups, namely, the side chains of the His6 and Phe8 residues.

Substituted pyrazolo corticoids as topical antiinflammatory agents.

The synthesis of a series of substituted pyrazolo corticoids is described. Of these 11beta,17alpha,21-trihydroxy-6,16alpha-dimethyl-4,6-pregnadieno[3,2-c]-2'-(4-pyridly)pyrazole (21) shows an excellent separation of systemic to local activity in the model animal test. Compound 21 exhibits high vasoconstriction activity in human volunteers and is clinically effective in the treatment of psoriasis.

Prepartion of 16alpha-alkoxy and 16alpha-acyloxy derivatives of 21-chloro-17-acyloxy corticosteroids and determination of their vasoconstrictor activities in humans.

A number of number of 16alpha-alkoxy and 16alpha-acyloxy derivatives of 21-chloro-17-acyloxy corticosteroids have been prepared. The synthetic routes used were (a) reaction of the 16alpha,17-disubstituted 21-mesylate with lithium chloride and (b) reaction of the 16alpha-substituted 17,21-cyclic ortho ester with triphenylmethyl chloride. The vasoconstrictor activities in humans exhibited by these compounds were significantly lower than that of a 16beta-methyl analogue.