Roberta Razzetti

New Surfactant with SP-B and C Analogs Gives Survival Benefit after Inactivation in Preterm Lambs

Background Respiratory distress syndrome in preterm babies is caused by a pulmonary surfactant deficiency, but also by its inactivation due to various conditions, including plasma protein leakage. Surfactant replacement therapy is well established, but clinical observations and in vitro experiments suggested that its efficacy may be impaired by inactivation. A new synthetic surfactant (CHF 5633), containing synthetic surfactant protein B and C analogs, has shown comparable effects on oxygenation in ventilated preterm rabbits versus Poractant alfa, but superior resistance against inactivation in vitro. We hypothesized that CHF 5633 is also resistant to inactivation by serum albumin in vivo. Methodology/Principal Findings Nineteen preterm lambs of 127 days gestational age (term = 150 days) received CHF 5633 or Poractant alfa and were ventilated for 48 hours. Ninety minutes after birth, the animals received albumin with CHF 5633 or Poractant alfa. Animals received additional surfactant if PaO2 dropped below 100 mmHg. A pressure volume curve was done post mortem and markers of pulmonary inflammation, surfactant content and biophysiology, and lung histology were assessed. CHF 5633 treatment resulted in improved arterial pH, oxygenation and ventilation efficiency index. The survival rate was significantly higher after CHF 5633 treatment (5/7) than after Poractant alfa (1/8) after 48 hours of ventilation. Biophysical examination of the surfactant recovered from bronchoalveolar lavages revealed that films formed by CHF 5633-treated animals reached low surface tensions in a wider range of compression rates than films from Poractant alfa-treated animals. Conclusions For the first time a synthetic surfactant containing both surfactant protein B and C analogs showed significant benefit over animal derived surfactant in an in vivo model of surfactant inactivation in premature lambs.

Pharmacokinetic and pharmacologic properties of delapril, a lipophilic nonsulfhydryl angiotensin-converting enzyme inhibitor

Delapril is a carboxy-alkyl-dipeptide mainly converted in animals and humans to an active diacid derivative (M-I), which in turn is converted to an active 5-hydroxy-indane diacid (M-III). In humans these metabolites are excreted in the urine. The presence of the indanyl-glycine moiety gives delapril a high lipophilicity, greater than several other angiotensin-converting enzyme (ACE) inhibitors, such as captopril and enalapril. Due to its greater lipophilicity, delapril has been shown to exert a more effective inhibition of vascular ACE than captopril and enalapril, both in vitro and in vivo. The activity of delapril on tissue ACE also lasts longer than on the circulating enzyme. At doses ranging from 1-10 mg/kg orally, delapril exerts a marked and long-lasting antihypertensive action in various experimental models of hypertension. The blood pressure reduction has been shown to be accompanied by suppression of angiotensin II release from the vascular wall. In stroke-prone spontaneously hypertensive rats (SHR-SP) and in SHR with chronic renal failure, besides reducing hypertension, delapril significantly improves survival rate and prevents the development of stroke, cardiac hypertrophy, and renal sclerosis. The ability of delapril to reduce hypertrophy in vascular and cardiac tissue has been demonstrated in both in vitro and in vivo experiments.

Comparative efficacy of a DA2/α2 agonist and a β-blocker in reducing adrenergic drive and cardiac fibrosis in an experimental model of left ventricular dysfunction after coronary artery occlusion

Attenuation of neuroendocrine activation may be beneficial in congestive heart failure. Sympathetic nervous system overactivity can be reduced by receptors blockade or by reducing norepinephrine (NE) spillover. This study evaluated and compared the effects of a DA2-dopaminergic receptor/alpha2-adrenoceptor agonist (CHF-1024) and a beta1-adrenoreceptor antagonist in terms of hemodynamics, ventricular remodeling, beta-adrenergic drive, and cardiac fibrosis after myocardial infarction (MI) in rats. MI was induced by left coronary artery ligation in 213 rats, whereas 12 were left unoperated on. After 2 months, the operated-on animals were treated for 1 more month with CHF-1024 at either 0.33 mg/kg/day (low dose) or 1 mg/kg/day (high dose) or with metoprolol (10 mg/kg/day), delivered through implanted osmotic minipumps. Plasma concentration and urinary excretion of NE were measured before the rats were killed. Hemodynamic variables were measured and morphometric analysis was done on the diastole-arrested hearts to quantify left ventricular remodeling and interstitial collagen density. Metoprolol treatment tended to normalize LV end-diastolic pressure (LVEDP). CHF-1024 at either dose, and metoprolol, significantly reduced collagen deposition in LV of infarcted animals (from 8.8 +/- 0.5% LV area in vehicle-treated rats to 6.6 +/- 0.2% or 6.4 +/- 0.2% after the low or high dose of CHF-1024, respectively; p < 0.05). Similarly, CHF-1024 at either dose reduced the plasma concentration of NE (from 224 +/- 53 pg/ml to 60 +/- 7 pg/ml or 87 +/- 13 pg/ml; p < 0.05) and urinary excretion of NE in rats with MI, whereas beta-blockade did not affect these variables. In conclusion, CHF-1024 infused for 1 month to rats with LV dysfunction reduced heart rate, NE spillover, and collagen deposition, without unwanted effects, only appearing at the higher dose. Effective beta-blockade with metoprotol reduced LVEDP with no effects on heart function. Neither DA2/alpha2 stimulation nor beta-blockade altered LV remodeling after coronary artery ligation.

Cardiovascular effects of nicardipine in anesthetized open-chest dogs in the absence and presence of β-adrenergic receptor blockade: a comparison with nifedipine and verapamil

Summary: Nicardipine, a new 1,4-dihydropyridine calcium-entry blocker, was assessed for cardiovascular effects against nifedipine and verapamil in anesthetized open-chest beagle dogs, in the absence and presence of β-adrenoceptor blockade (propranolol 1 mg/kg i.v.). In control conditions, intravenous nicardipine and nifedipine (30 nmol/kg) produced decreases in blood pressure of similar magnitude without evidence of cardiodepression. An equihypotensive dose of verapamil (300 nmol/kg), by contrast, induced long-lasting negative chronotropic and inotropic effects, which, when combined with the effects of propranolol, were so marked as to cause the death of two of five dogs (atrioventricular block). Dihydropyridine derivatives at higher doses (100 nmol/kg) produced different responses: nifedipine depressed cardiac performance significantly more than nicardipine and, in the presence of β-adrenergic blockade, caused the death of three of six dogs due to cardiovascular failure. In the nicardipine group, on the contrary, cardiac function was adequately preserved even in the presence of β-blocker, and no animals died. The results of the present study confirm a previous in vitro observation: nicardipine is a calcium-entry blocker devoid of remarkable cardiodepressant effects and particularly selective for the vascular smooth muscle.

The involvement of the release of nitric oxide in the pharmacological activity of the new furoxan derivative CHF 2363

1 The mechanism of action and the pharmacological effects of the new furoxan derivative, CHF 2363 (4‐ethoxy‐3‐phenylsulphonylfuroxan), were investigated. 2 Pre‐incubation of CHF 2363 with human platelet‐rich plasma produced a concentration‐dependent inhibition of the platelet aggregation induced by collagen, adenosine diphosphate (ADP) and platelet activating factor (PAF). The test compound was about 5 times more potent than sodium nitroprusside. 3‐Isobutyl‐1‐methyl‐xanthine (IBMX) potentiated the antiaggregating effect of CHF 2363. 3 CHF 2363 was a potent inhibitor of rubbed endothelium rabbit aortic ring contraction induced by noradrenaline. Comparison of IC50 values showed that CHF 2363 was as potent as glyceryl trinitrate (GTN). 4 Increasing concentrations of CHF 2363 elevated platelet guanosine 3′:5′‐cyclic monophosphate (cyclic GMP) levels. Adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) levels were unaffected. 5 Oxyhaemoglobin reduced all the pharmacological actions of the test compound. Moreover, CHF 2363 concentration‐dependently released nitric oxide (NO) in platelet‐rich plasma. The NO release was correlated to its ability to increase platelet cyclic GMP levels. 6 After exposure of rat aortic strips to supramaximal concentrations of GTN (550 μm), the vasorelaxant activity of CHF 2363 did not change, although that of GTN decreased about 55 fold. 7 It has been concluded that the new furoxan derivative CHF 2363 exerts a potent antiaggregating and vasorelaxant activity via NO release and increase of cyclic GMP levels. No in vitro cross tolerance between GTN and CHF 2363 was observed.

Bronchodilator Activity of (3R)-3-[[[(3-fluorophenyl)[(3,4,5-trifluorophenyl)methyl]amino] carbonyl]oxy]-1-[2-oxo-2-(2-thienyl)ethyl]-1-azoniabicyclo[2.2.2]octane bromide (CHF5407), a Potent, Long-Acting, and Selective Muscarinic M3 Receptor Antagonist

The novel quaternary ammonium salt (3R)-3-[[[(3-fluorophenyl)[(3,4,5-trifluorophenyl)methyl]amino]carbonyl]oxy]-1-[2-oxo-2-(2-thienyl)ethyl]-1-azoniabicyclo[2.2.2]octane bromide (CHF5407) showed subnanomolar affinities for human muscarinic M1 (hM1), M2 (hM2), and M3 (hM3) receptors and dissociated very slowly from hM3 receptors (t½ = 166 min) with a large part of the receptorial complex (54%) remaining undissociated at 32 h from radioligand washout. In contrast, [3H]CHF5407 dissociated quickly from hM2 receptors (t½ = 31 min), whereas [3H]tiotropium dissociated slowly from both hM3 (t½ = 163 min) and hM2 receptor (t½ = 297 min). In the guinea pig isolated trachea and human isolated bronchus, CHF5407 produced a potent (pIC50 = 9.0–9.6) and long-lasting (up to 24 h) inhibition of M3 receptor-mediated contractile responses to carbachol. In the guinea pig electrically driven left atrium, the M2 receptor-mediated inhibitory response to carbachol was recovered more quickly in CHF5407-pretreated than in tiotropium-pretreated preparations. CHF5407, administered intratracheally to anesthetized guinea pigs, potently inhibited acetylcholine (Ach)-induced bronchoconstriction with an ED50 value of 0.15 nmol/kg. The effect was sustained over a period of 24 h, with a residual 57% inhibition 48 h after antagonist administration at 1 nmol/kg. In conscious guinea pigs, inhaled CHF5407 inhibited Ach-induced bronchoconstriction for at least 24 h as did tiotropium at similar dosages. Cardiovascular parameters in anesthetized guinea pigs were not significantly changed by CHF5407, up to 100 nmol/kg i.v. and up to 1000 nmol/kg i.t. In conclusion, CHF5407 shows a prolonged antibronchospastic activity both in vitro and in vivo, caused by a very slow dissociation from M3 receptors. In contrast, CHF5407 is markedly short-acting at M2 receptors, a behavior not shared by tiotropium.

Effects of a DA2/α2 agonist and a β1-blocker in combination with an ACE inhibitor on adrenergic activity and left ventricular remodeling in an experimental model of left ventricular dysfunction after coronary artery occlusion

Renin-angiotensin-aldosterone and sympathetic nervous systems overactivity play a major role in worsening the extent of heart failure. Attenuation of neurohumoral activation with angiotensin-converting enzyme (ACE) inhibitors and beta-blockers has proven beneficial in congestive heart failure. Because ACE inhibition is a recommended treatment for heart failure, this study was designed to test the effects on neurohumoral activation, hemodynamics, and left ventricular (LV) volume of the combination of an ACE inhibitor (delapril) with a DA2-dopaminergic receptor/alpha2-adrenoceptor agonist (CHF-1024) or a beta1-adrenoceptor antagonist (metoprolol) after a moderate to large myocardial infarction (MI) in rats. MI was induced by left coronary artery ligation in 134 rats, and six were not operated on. After 2 months, the animals with ECG evidence of MI were treated for 1 more month with CHF- 1024, 0.33 mg/kg/day or with metoprolol (10 mg/kg/day), delivered through implanted osmotic minipumps, in addition to delapril (6 mg/kg/day) in the drinking water. Daily urinary excretion of norepinephrine (NE) and circulating concentration were measured. Hemodynamic variables were measured, and three-dimensional morphometric analysis was done on the diastole-arrested hearts to quantify infarct size and LV geometry. In conscious animals, delapril alone or with CHF-1024 or metropolol did not modify heart rate or systolic blood pressure. Both combination treatments, however, significantly reduced heart rate in anesthetized animals compared with the group receiving vehicle. Infarct size was not different between treatments, averaging 20-22% of LV volume. The threefold increase of LV chamber volume in infarcted rats was significantly attenuated by delapril alone or with CHF-1024 or metoprolol (-37 to -44%, p<0.05). Treatment with a combination of the ACEi and CHF-1024 tended to normalize the shape of the LV cavity. Urinary NE excretion was unaffected by delapril alone but was reduced by the addition of CHF-1024 or metoprolol. In conclusion, 1 month of treatment with doses of delapril having no hemodynamic effect, reduced LV volume in a model of chronic heart failure. When CHF-1024 or metoprolol was given with delapril, sympathetic activation decreased with no unwanted effects, such as excessive hypotension.

CHF-1024, A DA2/α2 Agonist, Blunts Norepinephrine Excretion and Cardiac Fibrosis in Pressure Overload

We compared the effects of an ACE inhibitor, captopril, with those of a DA2-dopaminergic/α2-adrenergic receptor agonist (CHF-1024) on neuroendocrine activation and cardiac fibrosis in a model of pressure-overload hypertrophy. Interrenal aortic stenosis was performed in 89 rats, treated with CHF-1024 (0.33, 2 or 6 mg kg−1 day−1), or captopril (1 g/L). Hemodynamic variables were recorded. Cardiac and renal weights, plasma aldosterone, renin activity and urinary catecholamine excretion were measured, as well as cardiac collagen. Blood pressure was lower in stenotic animals treated with CHF-1024 compared to vehicle (161 ± 10 vs 219 ± 10 mmHg, p < 0.01), but LV weight was similar. CHF-1024 elicited a marked dose-dependent attenuation of urinary norepinephrine excretion (1.80 ± 0.18 in controls compared to 0.40 ± 0.14 μg/24 h at the highest dose, p < 0.01) and of LV perivascular fibrosis. Captopril provoked a marked hypotension, reduced cardiac and body weights, plasma aldosterone concentration, dopamine excretion and perivascular collagen. The DA2/α2 agonist CHF-1024 effectively blunts adrenergic drive and cardiac fibrosis in a rat model of pressure overload.

β2-Adrenoceptor blockade is the basis of guinea-pig bronchial hyper-responsiveness to leukotriene C4 and other agonists

1 Four β‐adrenoceptor antagonists, namely (−)‐propranolol, (+)‐propranolol, ICI‐118551 and (±)‐practolol, were investigated for their effects on leukotriene C4 (LTC4)‐induced bronchoconstriction in the anaesthetized guinea‐pig. (−)‐Propranolol was also investigated for its effects on acetylcholine and histamine bronchospasm in the anaesthetized guinea‐pig, and on LTC4‐induced contractions of guinea‐pig isolated trachea and lung parenchyma. 2 The various β‐adrenoceptor antagonists potentiated, dose‐dependently, the bronchoconstriction induced by threshold doses of LTC4 and the intensity of the potentiation correlated with the β2‐blocking capacity possessed by the drugs. 3 (−)‐Propranolol potentiated the bronchospasm induced by threshold doses of acetylcholine and histamine but to a lesser degree than the LTC4‐induced bronchospasm. 4 The airway hyper‐responsiveness induced by (−)‐propranolol was unaffected by pretreatment with mepyramine, cyproheptadine, phenoxybenzamine, atropine or indomethacin. 5 The airway hyper‐responsiveness induced by (−)‐propranolol persisted even in adrenalectomized or reserpine‐treated guinea‐pigs, although adrenalectomy induced some increase in airway responsiveness. 6 (−)‐Propranolol had no effect on LTC4, histamine and acetylcholine‐induced contractions of isolated trachea and lung parenchyma. 7 The results show that the airway hyper‐responsiveness induced by β‐adrenoceptor antagonists generally correlates with their β2‐blocking activity. The possibility remains that some other unknown mechanism(s) may also be implicated.

Positive interaction of the β2-agonist CHF 4226.01 with budesonide in the control of bronchoconstriction induced by acetaldehyde in the guinea-pigs

1 Pretreatment of anaesthetized guinea‐pigs with either CHF 4226.01 (8‐hydroxy‐5‐[(1R)‐1‐hydroxy‐2‐[N‐[(1R)‐2‐(p‐methoxyphenyl)‐1‐methylethyl]amino]ethyl] carbostyril hydrochloride), formoterol or budesonide reduced acetaldehyde (AcCHO)‐evoked responses in the lungs with a rank order of potency CHF 4226.01 (ED50 values, from 1.88 to 3.31 pmol) > formoterol (ED50 values, from 3.03 to 5.51 pmol) ≫ budesonide (ED50 values, from 335 to 458 nmol). The duration of action of CHF 4226.01 in antagonizing the airway obstruction elicited by AcCHO was also substantially longer than formoterol (area under the curve) at 10 pmol, 763±58 and 480±34, respectively; P<0.01). 2 Continuous infusion of a subthreshold dose of AcCHO enhanced the intratracheal pressure (ITP) increases caused by subsequent challenges with substance P (from 9.7±0.8 to 27.5±1.6 cm H2O as a peak, P<0.001). Pretreatment with either CHF 4226.01 or formoterol prevented the sensitizing effect of AcCHO on substance P responses (ED50 values, 2.85 and 6.11 pmol, respectively; P<0.01). 3 The ED50 value of budesonide (396 nmol) in preventing AcCHO‐evoked ITP increase was reduced when this glucocorticoid was combined with 0.1 pmol CHF 4226.01 (ED50 76 nmol; P<0.001). CHF 4226.01/budesonide was two‐fold more effective (P<0.01) than the formoterol/budesonide combination. 4 These results suggest that CHF 4226.01/budesonide, by optimizing each others beneficial potential in the control of pulmonary changes caused by AcCHO in the guinea‐pigs, may represent a new fixed combination in asthma.