Calcium channel blocking action of franidipine hydrochloride (CV-4093.2HCl) in vitro and in vivo

Role of manidipine in the management of patients with hypertension

Manidipine is a third-generation dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. In clinical studies, manidipine has been shown to significantly lower office and 24-h blood pressure compared with placebo in patients with essential hypertension. The resulting reduction in blood pressure is maintained over 24 h, with preservation of the circadian blood pressure pattern; its blood pressure-lowering capacity appears to be similar to that of other calcium antagonists. In elderly patients with mild-to-moderate essential hypertension, manidipine is able to significantly decrease blood pressure compared with placebo for up to 3 years of treatment. The drug also significantly lowers blood pressure in patients with hypertension and concomitant Type 2 diabetes mellitus or renal impairment, and is devoid of adverse metabolic effects. It is well-tolerated with few untoward adverse effects related to vasodilation. In particular, manidipine appears to have less potential for pedal edema than other calcium channel blockers.

Manidipine: a review of its use in the management of hypertension

Manidipine is a lipophilic, third-generation dihydropyridine calcium channel antagonist with a high degree of selectivity for the vasculature, thereby inducing marked peripheral vasodilation with negligible cardiodepression. In addition, manidipine does not significantly affect norepinephrine levels, suggesting a lack of sympathetic activation. It has a gradual onset of action and a long duration of action enabling once daily administration. Furthermore, manidipine dilates both the efferent and the afferent renal arterioles and appears to have beneficial renal effects unrelated to its antihypertensive effect. Once-daily oral manidipine is an effective and generally well tolerated antihypertensive agent for younger and elderly adult patients with mild-to-moderate hypertension. In particular, in a large double-blind trial, the incidence of ankle oedema was significantly lower in manidipine than in amlodipine recipients. Manidipine is also effective in hypertensive patients with comorbidities, such as type 2 diabetes mellitus and/or renal impairment, and appears to improve insulin sensitivity without affecting metabolic function. Thus, manidipine represents a first-line treatment option for patients with essential mild-to-moderate hypertension.

Multivariate least squares regression applied to the spectrophotometric analysis of manidipine and its main photoproduct

The simultaneous quantitative assay of 1,4-dihydropyridine calcium antagonist manidipine and its main photodegradation by-product has been defined by using a multivariate calibration on UV spectra based on a classical least squares regression. Optimization of the procedure was achieved by means of a calibration model using suitable wavelength ranges singled out from a fractionation scheme thereat defined. Recovery values of 99 and 96% for the drug and the by-product, respectively, were found either in appropriately prepared mixtures and commercial formulations. Quantification limit for the photoproduct concentration was estimated as 1.0% for the reference samples.

Manidipine: a review of its use in hypertension

Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40 mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in noncomparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mglday) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or moderate essential hypertension. The BP-lowering effects of the drug in patients with hypertension and type 2 diabetes mellitus or impaired glucose tolerance were not associated with any adverse metabolic effects. The effects of manidipine on UAE in this patient group remain unclear. Manidipine provides an additional treatment option for patients for whom dihydropyridine calcium antagonists are appropriate. Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in non-comparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mg/day) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or mo

AE0047-mediated calcium channel blocking in vascular smooth muscles

1. This experiment was designed to pharmacologically characterize a novel calcium channel blocker, AE0047. 2. After 1-hr treatment with each drug (10(-6) M), K(+)-induced contraction in rat aortic strip was clearly depressed by nifedipine and manidipine and slightly depressed by AE0047. After a wash out of the preparation in drug-free medium, the inhibition of K(+)-induced contraction by nifedipine or manidipine was abolished or unchanged, respectively. In contrast, AE0047-produced inhibition was reinforced with time after removal of the drug. 3. A cell membrane depolarization-induced 45Ca uptake into tissue was depressed completely by nifedipine, but, if it was washed out, merely 20% inhibition of control remained. AE0047-produced inhibition became prominent after drug removal. Manidipine did not have the same inhibitory effect after wash out. 4. A receptor-binding study indicated that affinity of AE0047 and manidipine for the dihydropyridine-sensitive Ca channel receptor was lower than that of nifedipine. AE0047, unlike nifedipine and manidipine, inhibited [3H]PN200-110 binding more strongly when a 4-hr preincubation was used than without extended incubation. 5. The drug molecule of AE0047 was highly partitioned into the lipid bilayer of the synaptosome in canine cerebral cortices. In the synaptic membrane and liposomes, both prepared from canine cerebral cortices, the respective partition coefficients of the drug were 6997 +/- 2309 and 422 +/- 28 against 1395 +/- 161 and 24 +/- 2 of nitrendipine. 6. AE0047 showed slower onset of inhibition against K(+)-induced contraction and enhanced Ca influx compared with manidipine and nifedipine. These results may suggest that AE0047 requires a long period of time to occupy the dihydropyridine-sensitive sites within the Ca channel, which was detected by decreased specific [3H]PN200-110 binding, and to inhibit K(+)-induced Ca influx into rat aorta.

Slow association of positively charged Ca2+ channel antagonist amlodipine to dihydropyridine receptor sites in rat brain membranes

1. No significant differences were observed in Kd and Bmax values between pH 7.2 (0.16 +/- 0.01 nM and 155.36 +/- 16.07 fmol/mg protein) and pH 10.0 (0.15 +/- 0.01 nM and 158.63 +/- 13.80 fmol/mg protein) in rat brain membranes. 2. The IC50 ratios at 0- and 270-min preincubations of amlodipine and manidipine at pH 7.2 were 23.09 and 10.25, respectively, whereas these ratios for these two drugs at pH 10.0 were 2.63 and 1.34, respectively. 3. In contrast, on treatment with nisoldipine, benidipine, SM-6586 and nifedipine, no significant differences were observed in the IC50 ratios between 0- and 270-min preincubations at pH 7.2 and 10.0.

Protective effects of manidipine on spermatogenesis in stroke-prone spontaneously hypertensive rats

1. We evaluated the protective effects of manidipine on spermatogenic damage induced by the hypertensive vascular changes in stroke-prone spontaneously hypertensive rats (SHRSP). 2. Blood pressure reached more than 250 mmHg in SHRSP at 15 weeks of age, and thereafter the hypertensive changes in testicular arterioles developed. Manidipine reduced both the blood pressure and the hypertensive vascular changes. 3. Although immature and mature spermatids greatly diminished in SHRSP at 23 weeks of age, manidipine could preserve almost normal spermatogenesis even at 23 weeks of age. Transferrin concentration in testicular cytosol, which was considered to be indicative of the Sertoli cell function, in SHRSP with manidipine administration was significantly higher than that in SHRSP with no treatment at 23 weeks of age. 4. In conclusion, manidipine could prevent the development of the hypertensive changes in intratesticular arterioles and maintain normal Sertoli cell function. As a result, manidipine protected spermatogenic damage in SHRSP.

Renal effects of manidipine hydrochloride. A new calcium antagonist in hypertensive patients

The renal effects of manidipine hydrochloride were investigated in ten hospitalised patients with mild-to-moderate essential hypertension. After a one-week placebo period, manidipine was given for 1 week in a dose rising from 5 mg to 10 mg or 20 mg daily to normalise the mean blood pressure measured after 2 h. Blood pressure had decreased from 171/101 to 147/86 mm Hg at the end of manidipine treatment. The pulse rate was unaltered. Renal vascular resistance decreased from 1.90 to 1.33 dyn.s.cm-5/1.48 m2 x 10(4), and renal blood flow and glomerular filtration rate increased from 522 to 662 ml.min-1 x 1.48 m-2 and from 81 to 93 ml.min-1 x 1.48 m-2, respectively, in spite of a fall in renal perfusion pressure. Manidipine reduced the filtration fraction from 0.260 to 0.243, suggesting a preferential reduction in efferent arteriolar resistance. The fractional excretion of sodium and potassium did not change. Manidipine did not produce any significant alteration in plasma renin activity or in the plasma aldosterone concentration. The results indicate that manidipine has favourable renal effects and a concomitant hypotensive action in patients with mild-to-moderate essential hypertension.

Effects of MPC-1304, a novel Ca2+ entry blocker, on alpha-adrenoceptor-mediated pressor responses in pithed rats

MPC-1304 is a novel Ca2+ entry blocker of the 1,4-dihydropyridine type. In the present study, the effect of oral administration of MPC-1304 on alpha-adrenoceptor-mediated pressor responses was examined in pithed rats and compared with that of nifedipine. Drugs were administered orally to conscious animals before pithing. MPC-1304 (0.3-3 mg/kg) and nifedipine (1-10 mg/kg) inhibited pressor responses to norepinephrine, phenylephrine (alpha 1-adrenoceptor agonist), UK-14304 (alpha 2-adrenoceptor agonist), and sympathetic nerve (spinal cord segments) stimulation. MPC-1304 was roughly 3 times more potent than nifedipine in inhibiting these responses. The inhibitory effect of MPC-1304 (3 mg/kg) on the pressor response to UK-14304 lasted longer than that of nifedipine (3 mg/kg). At the same time, plasma concentrations of MPC-1304 were lower than those of nifedipine. These results suggest that MPC-1304 has a great ability to inhibit pressor responses to norepinephrine and peripheral sympathetic stimulation after its oral administration, and that this effect of MPC-1304 is closely correlated with its potent antihypertensive activity.

Studies on the glomerular microcirculatory actions of manidipine and its modulation of the systemic and renal effects of endothelin

We examined the actions of intravenously administered manidipine on systemic and renal microcirculatory hemodynamics and its efficacy in antagonizing endothelin-1 (ET-1)-evoked responses. Manidipine was a potent vasodilator with preferential activity in the renal vasculature. Its administration in optimal doses resulted in decreases in systemic arterial pressures accompanied by increases in renal perfusion and filtration rates. Its primary sites of action in the kidney were at both pre- and postglomerular arteriolar sites. Manidipine was capable of near-total reversal of the sustained elevations in arterial pressure and the progressive reductions in renal blood flow and glomerular filtration rates induced by intravenously administered ET-1. In the presence of prolonged calcium channel blockade, subsequent administration of ET-1 led to paradoxic hypotensive responses, which could be profound and blocked by an inhibitor of nitric oxide synthesis. These unexpected vasorelaxant actions of ET-1 in the presence of manidipine were likely caused by the dual effects of antagonism of its own intrinsic vasoconstrictor action (through calcium channel blockade), as well as ET-1-evoked release of the endothelium-derived relaxing factor, nitric oxide.

Pharmacologic characteristics of a new calcium antagonist, manidipine: beneficial effects on renal circulation and vascular changes

The calcium antagonist, manidipine, was developed on the basis of the hypothesis that antihypertensive drugs that act to improve renal hemodynamic alterations will be therapeutically beneficial in hypertensive patients. Manidipine shows long-lasting calcium channel-blocking action in vascular smooth muscle cells and antihypertensive actions in various types of hypertensive models. The drug has high selectivity for resistance vessels, dilates renal vasculature, and inhibits renal vascular constrictions induced by norepinephrine and angiotensin II in spontaneously hypertensive rats. It increases renal blood flow and has a prominent natriuretic action without changing glomerular filtration rate. The coronary dilating effect of the drug is similar to that of nifedipine, but its cardiodepressant effects are less potent than those of other dihydropyridines. Furthermore, manidipine prevents the development of cerebrovascular lesions and inhibits the progression of vascular damage in the brain and kidneys of stroke-prone spontaneously hypertensive rats. The drug also inhibits a proliferative response of the intima to balloon catheter-induced injury in the carotid arteries of spontaneously diabetic rats without affecting plasma lipids or blood pressure. These results suggest that manidipine may be useful for the treatment of hypertensive patients with or without vascular complications.

New synthetic ligands for L-type voltage-gated calcium channels

The pharmacology of the L-type Ca2+ channel has been the subject of considerable basic and clinical investigation over the past two decades primarily because of the clinical activities of nifedipine, verapamil and diltiazem. However, it is quite clear that this Ca2+ channel is, in common with other pharmacologic receptors, a multiple drug receptor. There are probably as many as six or more discrete drug binding sites associated with this Ca2+ channel. Continued investigation of these sites may yield both new therapeutic agents, structural clues to ligands active at other classes of Ca2+ channel and structures active at other classes of ion channel.