Pharmacokinetics and pharmacodynamics of conventional and slow release forms of nifedipine in essential hypertensive patients

Relationship between prolonged gestation and nifedipine pharmacokinetics in long-term tocolysis

In this study, we examined the pharmacokinetics of nifedipine and investigated the maternal and foetal background factors that prolong pregnancy in pregnant women undergoing long-term tocolysis. This prospective observational study included 38 pregnant women hospitalised for threatened preterm labour and treated with nifedipine extended-release tablets in combination with an intravenous ritodrine infusion. Maternal plasma nifedipine concentrations were determined using high-performance liquid chromatography. All patients were administered 20 or 40 mg/dose of nifedipine every 6 h at the time of blood sampling. The plasma trough concentration (Ctrough ) was 22.6 ± 17.3 ng/mL, the maximum plasma concentration (Cmax ) was 30.9 ± 15.3 ng/mL and the time to maximum concentration (Tmax ) was 1.70 ± 1.10 h, as determined using noncompartmental analysis (NCA). The area under the curve for drug concentration (AUCtau ) was 152.3 ± 91.8 mg/L・h, and oral clearance (CL/F) was 0.17 ± 0.08 L/h. Using logistic regression analyses, we identified the factors that predicted term delivery from 37 weeks to <42 weeks of gestation. Gestational age at admission and the AUCtau of nifedipine can predict term delivery. The AUCtau of nifedipine is a valuable regulatory predictor of term delivery in pregnant women undergoing long-term tocolysis.

Glycosuria medicated with ipragliflozin and nifedipine or ipragliflozin and candesartan: a case report

Introduction

Animal studies have reported that treatment with angiotensin II receptor blockers reduced kidney sodium-dependent glucose cotransporter expression. We therefore hypothesized that patients with hypertension treated with an angiotensin II receptor blocker (candesartan) would probably have an increased response to sodium-dependent glucose cotransporter inhibitor therapy (ipragliflozin) compared with patients treated with alternative hypertensive medications such as calcium channel blockers (nifedipine).

Although sodium-dependent glucose cotransporter inhibitor (ipragliflozin) is a new anti-diabetic medicine, the clinical efficacy in the Japanese population has not been fully evaluated. We compared the combined effect of angiotensin II receptor blocker candesartan plus ipragliflozin with nifedipine plus ipragliflozin therapy and found that the combination of candesartan plus ipragliflozin was more effective in increasing glycosuria and lowering plasma glucose.

Case presentation

A 57-year-old Japanese man with essential hypertension was treated with candesartan. Candesartan was switched to nifedipine for the initial 10 days of an observation period and 5 days later he was started on ipragliflozin (day 6 of nifedipine treatment) with nifedipine for the next 5 days. Thereafter (from day 11 to day 20), candesartan was started instead of nifedipine and ipragliflozin was continued. In the last 5 days ipragliflozin was stopped and he was treated with candesartan alone. Neither nifedipine alone (0.038+/-0.004) nor candesartan alone (0.048+/-0.006) produce any trace amount of glycosuria. However, the extent of glycosuria under ipragliflozin with candesartan treatment (37.5+/-8.45) was significantly greater than that of ipragliflozin with nifedipine (23.75+/-0.35; P<0.05).

Conclusion

Candesartan demonstrated additive actions with ipragliflozin to increase glycosuria compared to ipragliflozin with nifedipine treatment.

Utilizing in vitro and PBPK tools to link ADME characteristics to plasma profiles: case example nifedipine immediate release formulation

One of the most prominent food-drug interactions is the inhibition of intestinal cytochrome P450 (CYP) 3A enzymes by grapefruit juice ingredients, and, as many drugs are metabolized via CYP 3A, this interaction can be of clinical importance. Calcium channel-blocking agents of the dihydropyridine type, such as felodipine and nifedipine, are subject to extensive intestinal first pass metabolism via CYP 3A, thus resulting in significantly enhanced in vivo exposure of the drug when administered together with grapefruit juice. Physiologically based pharmacokinetic (PBPK) modeling was used to simulate pharmacokinetics of a nifedipine immediate release formulation following concomitant grapefruit juice ingestion, that is, after inhibition of small intestinal CYP 3A enzymes. For this purpose, detailed data about CYP 3A levels were collected from the literature and implemented into commercial PBPK software. As literature reports show that grapefruit juice (i) leads to a marked delay in gastric emptying, and (ii) rapidly lowers the levels of intestinal CYP 3A enzymes, inhibition of intestinal first pass metabolism following ingestion of grapefruit juice was simulated by altering the intestinal CYP 3A enzyme levels and simultaneously decelerating the gastric emptying rate. To estimate the in vivo dispersion and dissolution behavior of the formulation, dissolution tests in several media simulating both the fasted and fed state stomach and small intestine were conducted, and the results from the in vitro dissolution tests were used as input function to describe the in vivo dissolution of the drug. Plasma concentration-time profiles of the nifedipine immediate release formulation both with and without simultaneous CYP 3A inhibition were simulated, and the results were compared with data gathered from the literature. Using this approach, nifedipine plasma profiles could be simulated well both with and without enzyme inhibition. A reduction in small intestinal CYP 3A levels by 60% was found to yield the best results, with simulated nifedipine concentration-time profiles within 20% of the in vivo observed results. By additionally varying the dissolution input of the PBPK model, a link between the dissolution characteristics of the formulation and its in vivo performance could be established.

Evaluation of changes in sympathetic nerve activity and heart rate in essential hypertensive patients induced by amlodipine and nifedipine

OBJECTIVE

To compare the effects of amlodipine and nifedipine on heart rate and parameters of sympathetic nerve activity during the acute and chronic treatment periods in order to elucidate their influence on cardiovascular outcome.

DESIGN

A randomized and single-blind study.

METHODS

We performed 24 h ambulatory electrocardiography and blood pressure monitoring of 45 essential hypertensive inpatients. Plasma and urinary catecholamine levels were measured during the control (pretreatment) period, on the first day (acute period) and after 4 weeks (chronic period) of administration of amlodipine and of short-acting nifedipine or its slow-releasing formulation. The low-frequency and high-frequency power spectral densities and low-frequency: high-frequency ratio were obtained by heart rate power spectral analysis.

RESULTS

Blood pressure was significantly and similarly reduced by administrations of amlodipine, short-acting nifedipine and slow-releasing nifedipine during the chronic period. The total QRS count per 24 h, which remained constant during the chronic period of administration of slow-releasing nifedipine and was increased by administration of nifedipine, was decreased by 2.8% by administration of amlodipine. Administration of amlodipine decreased the plasma and urinary norepinephrine levels during the chronic period, whereas the levels were significantly increased by administration of short-acting nifedipine and not changed by administration of slow-release nifedipine. Although low-frequency: high-frequency ratio was increased significantly by administration of short-acting nifedipine and slightly by administration of slow-releasing nifedipine, administration of amlodipine reduced it during the acute and chronic periods.

CONCLUSIONS

Administration of amlodipine did not induce an increase in sympathetic nerve activity in essential hypertensive patients during the chronic period, suggesting that beneficial effects on essential hypertension can be expected after its long-term administration. Administration of slow-releasing nifedipine induces milder reflex sympathetic activation than does that of short-acting nifedipine.

Analysis of nifedipine and its pyridine metabolite dehydronifedipine in blood and plasma: review and improved high-performance liquid chromatographic methodology

A reversed-phase HPLC method is described for the simultaneous determination of nifedipine and its primary pyridine metabolite dehydronifedipine in blood and plasma, that involves UV detection and neutral (blood) or alkaline (plasma) extraction. The limit of reliable determination is found to be 3 ng ml-1 with an inter-assay RSD of below 11%. In the presence of haemoglobin, nifedipine is unstable at pH greater than 10, necessitating neutral extraction for the measurement of nifedipine in haemolysed blood. Published methods for analysis of nifedipine are reviewed, emphasizing the lack of specificity and sensitivity which render many of them unsuitable for the investigation of nifedipine disposition in man.

Influence of age on the nocturnal fall of blood pressure and its modulation by long-acting calcium antagonists

The clinical significance of the nocturnal fall of blood pressure (BP) was examined. BP was monitored every 5 min for 24 hrs by means of a finger volume oscillometric device. The nocturnal fall was observed in all age groups (young: less than 40, n = 49; adult: 40 less than or equal to less than 60, n = 110; old: 60 less than or equal to, n = 33). The amplitude of nocturnal fall of BP (averaged daytime blood pressure--averaged nighttime blood pressure) in old patients (systolic = 13 +/- 11, diastolic = 10 +/- 8 mmHg, mean +/- SD) was similar to that in the young patients (systolic = 11 +/- 8, diastolic = 10 +/- 8 mmHg). These 192 subjects were also classified according to mean BP level (MBP) averaged for daytime in the ambulatory blood pressure monitoring records [MBP less than 85 (mmHg), n = 31; 85 less than or equal to MBP less than 100, n = 72; 100 less than or equal to MBP less than 115, n = 49; 115 less than or equal to MBP, n = 25]. BP level did not affect the pattern of circadian variation in the normal subjects or in the essential hypertensive patients at WHO stage I or II. The amplitude of the nocturnal fall in systolic BP increased with the increase in BP level, but this was not the case with diastolic BP (mean daytime BP less than 85 mmHg: systolic = 11 +/- 8, diastolic = 8 +/- 6 mmHg; 85 less than or equal to less than 100: systolic = 14 +/- 8, diastolic = 11 +/- 6 mmHg; 100 less than or equal to less than 115: systolic = 17 +/- 9, diastolic = 11 +/- 8; 115 less than or equal to: systolic 17 +/- 8, diastolic = 11 +/- 6 mmHg). Nitrendipine (8.6 +/- 5.6 mg, 22.5 +/- 11.4 days, n = 14) and nisoldipine (9.3 +/- 6.2 mg, 21.5 +/- 11.4 days, n = 15) administered once daily in the morning or nifedipine slow release tablet, 20 mg twice daily (n = 15, 17.7 +/- 5.2 days) induced a significant downward shift in the circadian BP pattern, in other words, the hypotensive effect was also observed during the night when the BP had already been low. Taken together, the information on the nocturnal behavior of BP would be valuable, especially in treating aged patients with essential hypertension with a long-acting antihypertensive drug.

The treatment of chilblains with nifedipine: the results of a pilot study, a double-blind placebo-controlled randomized study and a long-term open trial

A pilot study, a double-blind placebo-controlled randomised study and a long term open trial have indicated that nifedipine is effective in the treatment of perniosis. At a dose of 20 mg to 60 mg daily, nifedipine significantly reduced the time to clearance of existing lesions and prevented the development of new chilblains. Nifedipine also reduced the pain, soreness and irritation of the lesions. A comparison of the pre- and post-treatment skin biopsies showed resolution of the dermal oedema and diminution of the perivascular infiltrate. An increase in cutaneous blood flow following administration of nifedipine suggests that the vasodilator action of this drug may be important in its action.