[Effect of palonidipine hydrochloride (TC-81), a new dihydropyridine derivative, on various myocardial ischemic models].

The antianginal effects of palonidipine, a novel 1,4-dihydropyridine derivative, and nifedipine on various myocardial ischemic models were compared. (1) Palonidipine at 0.5 mg/kg, p.o. significantly inhibited vasopressin-induced ST depression of ECG in Donryu rats. This activity was about 5 times more potent than that of nifedipine and was long-lasting. (2) Palonidipine at 1 mg/kg, i.d. significantly inhibited ST depression induced by isoproterenol in Wistar rats. This activity of TC-81 was more potent than that of nifedipine. (3) Palonidipine at 3 micrograms/kg, i.v. produced an increase in regional myocardial tissue blood flow in the ischemic region of chronic coronary artery occluded dogs. (4) In isolated dog coronary artery, palonidipine at a concentration of 10(-10) M or greater inhibited the amplitude of 3,4-DAP-induced cyclic contractions in a concentration-dependent manner. This activity was 10-30 times more potent than that of nifedipine. (5) An intracoronary injection of endothelin (30 pmol/kg) reduced the coronary blood flow, subepicardial tissue blood flow, and subepicardial pH in anesthetized dogs. The ST elevation of ECG over 0.1 mV also occurred in 8 of 10 cases. In all the cases, ventricular extrasystoles were noted, and 9 out of 10 animals died. Pretreatment with palonidipine (3 micrograms/kg, i.v.) inhibited endothelin-induced ischemic changes, with a potency greater than that of nifedipine. These results suggest that palonidipine may be useful for the therapy of angina-pectoris.

[Effect of palonidipine hydrochloride (TC-81), a novel calcium antagonist, on the canine coronary artery].

The effects of palonidipine hydrochloride [TC-81: (+/-)-3-benzylmethylamino)-2,2-dimethylpropyl methyl 4-(2-fluoro-5-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate hydrochloride], a new calcium antagonist, on the coronary artery were studied in dogs. In the isolated canine coronary artery, TC-81 inhibited high K+ (60 mM)-induced contraction in a concentration-dependent manner. The relaxant activity of TC-81 was equal to that of nicardipine and more potent than those of nifedipine and diltiazem. TC-81 increased coronary blood flow in a dose-dependent manner after i.v.-administration in anesthetized open-chest dogs. The activity of TC-81 was equal to that of nifedipine or nicardipine, but the duration of its effect was longer than that of nifedipine or nicardipine. By oral administration in conscious dogs, TC-81 increased coronary blood flow at 0.1 mg/kg or more, and its activity was 10 times more potent than that of nifedipine. These results suggest that TC-81 increases coronary blood flow and is capable of improving the oxygen supply-demand relationship during angina pectoris.

[Inhibitory effects of palonidipine hydrochloride (TC-81) on contractions induced by various vasoconstrictors in rat aorta].

Inhibitions by palonidipine hydrochloride (TC-81), a new Ca entry blocker, of the contractile responses to norepinephrine (NE), serotonin (5-HT), prostaglandin F2 alpha (PGF2 alpha) and U-46619, a thromboxane A2 analog, were investigated in isolated rat aorta strips and compared with the inhibition of the high K+ response. TC-81 and nicardipine inhibited the contractile responses to NE, 5-HT, PGF2 alpha, and U-46619 in a concentration-dependent manner, but their relative inhibitions were less than 50% at 10(-8) M. In a Ca(2+)-free medium, 2-hr pretreatment with TC-81 or nicardipine did not inhibit the contractile responses to various vasoconstrictors, but it inhibited the responses to the addition of Ca. Their inhibitory potencies were less than the inhibition with high K+. Also, the treatment with TC-81 or nicardipine at 10(-7) M did not affect the tissue level of cyclic AMP. These results suggest that in isolated rat aorta, the inhibition by TC-81 of the contractile responses to NE, 5-HT, PGF2 alpha and U-46619 is not due to inhibition of intracellular Ca2+ release or an increase in cyclic AMP; rather, it is due to inhibition of the Ca2+ influx. This inhibitory effect was less than that seen on the high K+ response.

Differences in responses to TC-81 among various arteries in dogs.

The vasodilation induced by TC-81 was investigated in vitro and in vivo. In helical strips of dog arteries precontracted with 65.4 mM KCl, TC-81, nicardipine, nifedipine, diltiazem, and papaverine produced concentration-dependent relaxation. The potencies of TC-81 were in the following order: basilar > coronary > femoral > renal > mesenteric arteries. The other drugs also showed a similar property of greater response in basilar and coronary arteries than in renal and mesenteric arteries. However, the difference in reactivity to TC-81 was greater. On the other hand, TC-81, nicardipine, and papaverine dose-dependently increased the blood flow in vertebral, coronary, and femoral arteries in anesthetized dogs. However, the blood flow in renal and mesenteric arteries was not changed or decreased. The decreases in vessel resistance induced by TC-81 were in the following order: vertebral > coronary > femoral > renal = mesenteric arteries, agreeing with the experimental results in vitro. These results suggest that Ca2+ antagonists have the pharmacological property of vasodilating cerebral and heart blood vessels more selectively than other arteries, and this property of TC-81 might be an advantage compared with other drugs.

Relationship between tissue content of TC-81 and relaxation of rat aorta.

This study dealt with the relationship between the relaxant action of TC-81, a new Ca2+ antagonist, and its distribution in rat aorta depolarized by high K+ (65.4 mM). The inhibitory effect by TC-81 on K(+)-induced contraction and 45Ca2+ uptake was strongly time-dependent. TC-81 and nicardipine, each 10(-9) M, produced gradual relaxation of high-K(+)-induced contraction. The tissue contents of TC-81 and nicardipine increased with time courses that reflected decreasing tension. Both the maximum tissue content of TC-81 and the maximum relaxation were significantly greater than those for nicardipine. Also, the relaxations produced by TC-81 and nicardipine were correlated with the logarithm of the content of each drug in muscle tissues. However, the dissociation of TC-81 from the tissues was slower than that of nicardipine. The data suggest that the action of TC-81 is closely related to a gradual distribution of drug into muscle tissue, resulting in a slow onset of action. Also, the saturation time of TC-81 was longer than that of nicardipine, thereby accounting for the greater relaxation with TC-81.

Synthesis and antihypertensive activity of 1,4-dihydropyridine derivatives with a 4-(disubstituted phenyl) ring and an aminoalkyl ester group: highly potent and long-lasting calcium antagonists.

New 1,4-dihydropyridine derivatives bearing a 4-(disubstituted phenyl) ring and an aminoethyl ester or an amino-2,2-dimethyl-propyl ester were synthesized and their antihypertensive activities were examined in normotensive rats and spontaneously hypertensive rats. The effects of phenyl substituents and ester groups on the antihypertensive activity are discussed. Several compounds showed a more potent antihypertensive activity than nicardipine and most compounds had a longer duration of action. Among them, 7B.HCl (TC-81) showed highly potent and long-lasting activity and was selected as a candidate for further pharmacological investigations.

The preclinical safety evaluation of human monoclonal antibody against cytomegalovirus.

The human monoclonal antibody against cytomegalovirus (Mab C23) was examined pharmacokinetically and toxicologically as part of the preclinical studies prior to approval for human use. Rats given repeated intravenous administrations of Mab C23 produced no antibodies against Mab C23 and maintained a blood Mab C23 level in a dose-dependent manner. However, pregnant rabbits produced antibodies against Mab C23. The half-life of Mab C23 in plasma was 15.9 days in rats, which was similar to that of normal human serum gamma-globulin (NHSG). Neither behavioral effects nor circulatory disturbance was found in mice, rats, and dogs even after a single intravenous injection of 100 or 200 mg/kg, which corresponds to 50 or 100 times the intended clinical dosage. The repeated doses of 2, 10, or 20 mg/kg of Mab C23 on six occasions with 1- or 2-week intervals elicited a transient decrease in leukocyte counts in rats given 10 or 20 mg/kg, but no adverse effects in cynomolgus monkeys. Mab C23 did not cause any reproductive or developmental toxicity when administered to rats and rabbits at dose levels of 20 mg/kg or less. However, pregnant animals showed lower plasma levels of Mab C23 than non-pregnant animals. The chromosomal aberration test disclosed no clastogenicity in human lymphocytes. An immunostaining for Mab C23 revealed no localizations in several tissues of cynomolgus monkeys given intravenous doses of Mab C23.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive effect of the new dihydropyridine calcium antagonist (+-)-3-(benzylmethylamino)-2,2-dimethylpropyl methyl 4-(2-fluoro-5-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedica rbo xylate hydrochloride in dogs.

The antihypertensive effect of TC-81 ((+-)-3-(benzylmethylamino)-2,2-dimethylpropyl methyl 4-(2-fluoro-5-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridine dicarboxylate hydrochloride, CAS 96515-74-1), a new calcium antagonist, was investigated in normotensive dogs (NTD) and renal hypertensive dogs (RHD). By oral administration, the antihypertensive activity of TC-81 (ED20% was 0.09 mg/kg p.o.) was about 18 times more potent in conscious RHD in comparison with nicardipine (ED20% was 1.65 mg/kg p.o.). Duration of the antihypertensive effect of TC-81 was about 2 times longer than that of nicardipine, and the response was elicited more slowly than that of nicardipine at equipotent dose. Similar results were observed more clearly by intravenous injection, but the potency of TC-81 was only 3 times higher than that of nicardipine in anesthetized dogs. Tolerance of the antihypertensive effect of TC-81 in daily dosing for 2 weeks and the rebound phenomena after discontinuance of the treatment were not observed in RHD. TC-81 at a concentration of 10(10)-3 x 10(-9) mol/l inhibited the KCl- or norepinephrine-induced contraction of isolated dog femoral artery. From these observations, TC-81 can be characterized as having a strong, long-lasting, and slow-onset antihypertensive activity, especially by oral administration. Therefore, this new calcium antagonist may be useful for long-term antihypertensive therapy.

Antihypertensive effect of the new calcium antagonist (+-)-3-(benzylmethylamino)-2,2-dimethylpropyl-methyl-4-(2-fluoro-5- nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate hydrochloride in rats.

The antihypertensive effect of TC-81 ((+-)-3-(benzylmethylamino)-2,2-dimethylpropyl-methyl-4-(2-f luoro-5- nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate hydrochloride), a new calcium antagonist, was investigated in normotensive and hypertensive rats. By oral administration, the antihypertensive activity of TC-81 (ED20% in spontaneous hypertensive rats (SHR), DOCA-salt hypertensive rats and renal hypertensive rats were 0.37, 0.32, and 0.38 mg/kg p.o., respectively) was 7-14 times more potent in conscious hypertensive rats in comparison with nicardipine. Duration of the antihypertensive effect of TC-81 was about 2 times longer than that of nicardipine, and the response was elicited more slowly than that of nicardipine at an equipotent dose. Similar results were observed by intravenous injection, but the potency of TC-81 was only 3 times higher than that of nicardipine in anesthetized rats. Tolerance of the antihypertensive effect of TC-81 in long-term daily dosing and the rebound phenomenon after discontinuance of the treatment were not observed in hypertensive rats. TC-81, at a concentration of 10(-10)-3 x 10(-9) mol/l, inhibited the KCl-induced contraction of isolated rat vascular preparations. Moreover, TC-81 inhibited the norepinephrine-induced contraction of isolated SHR aorta preparation, but in isolated normotensive rat aorta, TC-81 inhibited the norepinephrine-induced contraction very little. From these observations, TC-81 can be characterized as having a strong, long-lasting, and slow-onset antihypertensive activity, especially by oral administration. Therefore, this new calcium antagonist may be useful for long-term antihypertensive therapy.

Effect of clenbuterol on contractile response in periurethral striated muscle of rabbits.

The effect of clenbuterol, a selective beta 2-adrenoceptor agonist, on isolated periurethral striated muscle preparations from rabbits has been investigated. The periurethral striated muscle produced a contraction in response to field stimulation. An application of clenbuterol resulted in a dose-dependent potentiation of the field stimulation-induced contraction. This potentiation was antagonized by propranolol and was greater than that of isoproterenol, suggesting a beta 2-agonistic action.

Effect of TC-81, a new dihydropyridine derivative, on K(+)-induced contraction in rat aorta.

TC-81 (3-(N-benzyl-N-methylamino)-2,2-dimethylpropyl methyl-2,6-dimethyl-4-(2-fluoro-5-nitrophenyl)-1,4-dihydro-pyridine- 3,5-dicarboxylate hydrochloride) is a new dihydropyridine derivative. The effects of TC-81 (10(-10)-10(-8) M) on high K(+)-induced contractions were investigated in isolated rat aorta, and the results were compared with those obtained with nicardipine, nifedipine, diltiazem and papaverine. All drugs produced concentration-dependent relaxation of K(+)-induced contractions. The rate of relaxation induced by TC-81 was slower than that induced by the other drugs at concentrations producing the same final inhibition. However, the relaxing activity of TC-81 was 2.2, 16.7, 550 or 44,000 times more potent than that of nicardipine, nifedipine, diltiazem or papaverine, respectively. The inhibitory effect of TC-81 was dependent on the duration of exposure to the agent and was antagonized when the external Ca2+ concentration was raised. TC-81 concentration dependently inhibited La(3+)-resistant 45Ca2+ uptake in high K+ solution. The data thus show that TC-81 produces a concentration-dependent and time-dependent Ca2+ antagonistic action and that it is more potent than the other drugs tested.

Effects of clenbuterol on resting tension and contractile response in vesicourethral smooth muscle of rabbits.

The effects of clenbuterol, a selective beta 2-agonist, on isolated smooth muscle preparations from the rabbit bladder body, bladder base and proximal urethra have been investigated. The inhibitory effects on resting tension and acetylcholine- and field stimulation-induced contractions in the bladder body were compared with those of flavoxate, atropine, and verapamil. Clenbuterol (10(-10)-10(-7) M) had a strong, concentration-dependent relaxant effect on resting tension of the bladder body, and the relaxant effect was antagonized by propranolol. However, clenbuterol had little effect on the bladder base or proximal urethra. Isoproterenol, a non-selective beta agonist, gave a similar result, but was less potent than clenbuterol. Flavoxate failed to reduce the resting tension, but rather enhanced the spontaneous rhythmic contraction in a concentration-dependent manner. Atropine had little effect. Verapamil produced a concentration-dependent relaxation in the bladder body. Acetylcholine-induced contraction in the bladder body was completely inhibited by pretreatment with atropine (10(-7) M). Clenbuterol, flavoxate, and verapamil concentration-dependently inhibited acetylcholine-induced contraction. Field stimulation-induced contraction in the bladder body was not completely inhibited by atropine. However, the residual contraction was completely inhibited by tetrodotoxin. Clenbuterol, flavoxate, and verapamil concentration-dependently inhibited field stimulation-induced contraction. The inhibitory effects of clenbuterol and verapamil were antagonized by an application of propranolol and an increase in external Ca, respectively. The data suggest that the selective relaxant effect of clenbuterol on the bladder body is due to beta 2-antagonistic action, resulting in the inhibition of the contractile response to acetylcholine or field stimulation. Also, its response was different from that of the other drugs used.

Abnormality of the delayed type hypersensitivity (DTH) response to Bordetella pertussis in spontaneously hypertensive rats (SHR).

The delayed type hypersensitivity (DTH) response of spontaneously hypertensive rats (SHR) was compared with that of Wistar Kyoto rats (WKY), a normotensive strain. SHR showed a lower DTH response to Bordetella pertussis than WKY, especially 48 to 72 hr after antigenic challenge. These results were observed before appearance of abnormality of antibody formation or blood pressure. The reduced DTH responses of SHR were partially restored by either transfer of WKY thymocytes or treatment with levamisole. Conversely, the transfer of SHR thymocytes into WKY rats tended to diminish the DTH response. These findings suggest that SHR have a disfunction of T lymphocytes involved in DTH response (e.g., increase of suppressor cells and/or decrease of helper cells).

Aggregation of platelets induced by novel synthetic secoprostaglandins.

Two series of 8-acetly-12-hydroxyalkadienoic acids and 14-hydroxy-9-oxoalkadienoic acid which can be regarded as 11,12- and 8,12- secoprostaglandin E2 were synthesized and evaluated for their biological properties. Key members of each series, 11,12-(8Ac-HAD) and 8, 12-seco-11-norprostaglandin E2 (14H-OAD), were found to induce platelet aggregation which were inhibited by preincubation of platelet rich plasma with prostaglandin I2 but not inhibited by indomethacin, 8Ac-HAD produced dose-dependent potent contraction of rabbit aorta. Injection of 8Ac-HAD (1 mg/kg) into vein of rat induced sudden death of the animal. Both compounds were stable and platelet aggregating activity did not decrease at least for four hours at 0 degree C. Structure-activity relationship study of the series were carried out. Reduction of the acetyl carbonyl and methoxime formation of 8Ac-HAD lowered platelet aggregating activity, and 8-propionyl substituent and 12-deoxy derivative of 8Ac-HAD showed no activity. 12 (R)-Isomer and dl 12-methyl derivative of 8Ac-HAD retained the platelet aggregating activity. Modification of omega-chain did not cause any essential effect on the activity. Unlike 8Ac-HAD, several modification of 14H-OAD failed to maintain the aggregating activity.

[Studies on biopharmacological actitivy of active vitamin D3 analogues (VII) Effect of 1 alpha-hydroxycholecalciferol on renal function in rats and Beagle dogs (author's transl].

In male Wistar rats, 1 alpha-HCC and 1 alpha, 25-DHCC induced diuretic effects in doses of 2.5 and 25 micrograms/kg p.o., while no such effects of 1 alpha-HCC were seen with a dose of 0.25 microgram/kg p.o. Effect of 1 alpha-HCC appeared later than that of 1 alpha, 25-DHCC, but at 24 hr, the difference disappeared. Similar results were obtained with urinary concentrations of calcium (increase) and phosphorus (decrease). Glomerular filtration rate (GFR) and tubular reabsorption of phosphate (TRP) were remarkably elevated by 1 alpha, 25-DHCC, and effects of 1 alpha-HCC were rather weak and apparently not dose dependent. In light of these results and the finding that there was no difference between the effects of 1 alpha-HCC and 1 alpha, 25-DHCC on serum calcium and phosphorus at 24 hr, the mechanism of action of these sterols on the renal function seems to differ. In male Beagle dogs, 0.25 microgram/kg/day p.o. of 1 alpha-HCC or 1 alpha, 25-DHCC induced a severe hypercalcemia and GFR was decreased in the 1 alpha, 25-DHCC treated group. A gradual recovery occurred with cessation of the administration. Thus decrease in GFR was considered to be due to calcification of the kidney.

[Biological activity of 1alpha-hydroxycholecalciferol (II). Effect on the metabolism of calcium and phosphorus in rats (author's transl)].

Effect of 1alpha-hydroxycholecalciferol on the metabolism of calcium and phosphorus was studied using Ca-labelled and non-labelled rats. With an oral daily dose of 2.5 or 12.5 microgram/kg of 1alpha-hydroxycholecalciferol, serum calcium, urine volume, urinary calcium excretion, urinary calcium concentration and water consumption increased, while fecal concentration, urinary phosphorus concentration and food consumption decreased. There was a lag time (1 or 2 days) between the increase of serum calcium and that of specific activity of serum calcium, and bone resorption was stimulated later than was intestinal calcium transport. After 10 days treatment, calcium concentration in the femur decreased, while a remarkable calcification was noted in soft tissues such as kidney, intestine, aorta, heart and muscle, although these effects were reduced with lower doses of the drug. With a smaller oral daily dose (0.1 or 0.5 microgram/kg), for 6 months, bone calcium and phosphorus concentration increased without soft tissue calcification. Thus, 1alpha-hydroxycholecalciferol may be an effective drug for patients with metabolic bone diseases.

[Biological activity of 1alpha-hydroxycholecalciferol (1). Effect on intestine and bone in rats (author's transl)].

Biological activity of 1alpha-hydroxycholecalciferol was studied in rats. 1alpha-Hydroxycholecalciferol was found to be more potent and rapidly active than vitamin D in stimulating intestinal calcium transport and calcium mobilization from bone both in normal and vitamin D deficient rats. 1alpha-Hydroxycholecalciferol was also active in nephrectomized and/or thyroparathyroidectomized rats both in intestine and bone. Although it is well known that 1alpha-hydroxycholecalciferol is metabolized to 1alpha, 25-dihydroxycholecalciferol in the liver, there is the possibility that the former is active without further metabolism. In rats in which hepatitis was induced by CCl4, 1alpha-hydroxycholecalciferol was active both in the intestine and in the bone, while it was inactive in hepatectomized rats. These data clearly demonstrate that 1alpha-hydroxycholecalciferol is not active by itself and must be metabolized in the liver. This idea also shows the lag time in response of rats to 1alpha-hydroxycholecalciferol has more potent antirachitic activity than vitamin D and does not lose its activity with chronic oral administration. In view of these findings, 1alpha-hydroxycholecalciferol appears to have a good potential for clinical application in cases of renal failure and metabolic bone diseases.

[Antiallergic asthma effect of ipatropium bromide (Sch 1000) in dogs (author's transl)].

Antiasthmatic effect of ipratropium bromide (Sch 1000) which is a quarternary ammonium derivative of atropine was investigated in comparison with atropine in anesthetized dogs. Asthmatic responses were provoked with inhalation of Ascaris suum antigen. Sch 1000 (0.1 approximately 0.3%) and atropine (0.1 approximately 0.3%) were given by inhalation for 10 min prior to or after the antigen inhalation. Pretreatment of Sch 1000 and atropine inhibited the increase in respiratory resistance (Rrs) induced by antigen by 55 approximately 75% and 25 approximately 50%, respectively. After treatment with each drug, the enhanced Rrs was reduced by 40 approximately 55% and 35 approximately 40%, respectively. The activity of Sch 1000 was three fold stronger than that of atropine. Sch 1000 and atropine also effectively inhibited the increase in airway secretion produced by antigen, while both drugs in 0.3% solution had no effect on the normal bronchial tone and secretion. The findings suggest that vagal activity is involved in allergy related asthma and inhalations of anticholinergic drugs such as Sch 1000 show promise in the treatment of bronchial asthma.