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Analytical Sciences : the International... 2017In order to overcome deficiencies for simultaneously determining felodipine (FDP) and metoprolol (MPL) with low recovery and low sensitivity, a new online SPE coupled...
In order to overcome deficiencies for simultaneously determining felodipine (FDP) and metoprolol (MPL) with low recovery and low sensitivity, a new online SPE coupled with the liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) method for the simultaneous quantitative determination of FDP and MPL in beagle dog plasma was established. The SPE extraction of FDP and MPL was performed on a Retain PEP Javelin column (10 × 2.1 mm, 5 μm), while the chromatographic separation was achieved on a ZORBAX SB-C18 (50 × 2.1 mm, 3.5 μm) analytical column. Multiple reaction monitoring operated in the positive ion mode was adopted in MS detection, and the precursors to the product ion transition values of m/z 384/338.1, 268/74.2 and 436.2/207.1 were used to measure FDP, MPL and the internal standard (valsartan). The high throughput, accurate and sensitive method for FDP and MPL was validated and applied to the bioavailability research of FDP and MPL in beagle dogs.
Topics: Animals; Chromatography, Liquid; Dogs; Felodipine; Internet; Male; Metoprolol; Solid Phase Extraction; Tandem Mass Spectrometry
PubMed: 28690250
DOI: 10.2116/analsci.33.755 -
European Journal of Pharmaceutics and... Dec 2023Intestinal drug solubility is a key parameter controlling absorption after the administration of a solid oral dosage form. The ability to measure fed state solubility in...
Intestinal drug solubility is a key parameter controlling absorption after the administration of a solid oral dosage form. The ability to measure fed state solubility in vitro is limited and multiple simulated intestinal fluid recipes have been developed but with no consensus which is optimal. This study has utilised nine bioequivalent simulated fed intestinal media recipes that cover over 90% of the compositional variability of sampled fed human intestinal fluid. The solubility of 24 drugs (Acidic; furosemide, ibuprofen, indomethacin, mefenamic acid, naproxen, phenytoin, piroxicam, valsartan, zafirlukast: Basic; aprepitant, atazanavir, bromocriptine, carvedilol, dipyridamole, posaconazole, tadalafil: Neutral; acyclovir, carbamazepine, felodipine, fenofibrate, griseofulvin, itraconazole, paracetamol, probucol) has been assessed to determine if structured solubility behaviour is present. The measured solubility behaviour can be split into four categories and is consistent with drug physicochemical properties and previous solubility studies. For acidic drugs (category 1) solubility is controlled by media pH and the lowest and highest pH media identify the lowest and highest solubility in 90% of cases. For weakly acidic, basic and neutral drugs (category 2) solubility is controlled by media pH and total amphiphile concentration (TAC), a consistent solubility pattern is evident with variation related to individual drug media component interactions. The lowest and highest pH × TAC media identify the lowest and highest solubility in 70% and 90% of cases respectively. Four drugs, which are non-ionised in the media systems (category 3), have been identified with a very narrow solubility range, indicating minimal impact of the simulated media on solubility. Three drugs exhibit solubility behaviour that is not consistent with the remainder (category 4). The results indicate that the use of two bioequivalent fed intestinal media from the original nine will identify in vitro the maximum and minimum solubility values for the majority of drugs and due to the media derivation this is probably applicable in vivo. When combined with a previous fasted study, this introduces interesting possibilities to measure a solubility range in vitro that can provide Quality by Design based decisions to rationalise drug and formulation development. Overall this indicates that the multi-dimensional media system is worthy of further investigation as in vitro tool to assess fed intestinal solubility.
Topics: Humans; Solubility; Hydrogen-Ion Concentration; Intestines; Pharmaceutical Preparations; Indomethacin; Intestinal Absorption
PubMed: 37890541
DOI: 10.1016/j.ejpb.2023.10.017 -
CPT: Pharmacometrics & Systems... Jun 2023In celiac disease (CeD), gastrointestinal CYP3A4 abundance and morphology is affected by the severity of disease. Therefore, exposure to CYP3A4 substrates and extent of...
In celiac disease (CeD), gastrointestinal CYP3A4 abundance and morphology is affected by the severity of disease. Therefore, exposure to CYP3A4 substrates and extent of drug interactions is altered. A physiologically-based pharmacokinetic (PBPK) population for different severities of CeD was developed. Gastrointestinal physiology parameters, such as luminal pH, transit times, morphology, P-gp, and CYP3A4 expression were included in development of the CeD population. Data on physiological difference between healthy and CeD subjects were incorporated into the model as the ratio of celiac to healthy. A PBPK model was developed and verified for felodipine extended-release tablet in healthy volunteers (HVs) and then utilized to verify the CeD populations. Plasma concentration-time profile and PK parameters were predicted and compared against those observed in both groups. Sensitivity analysis was carried out on key system parameters in CeD to understand their impact on drug exposure. For felodipine, the predicted mean concentration-time profiles and 5th and 95th percentile intervals captured the observed profile and variability in the HV and CeD populations. Predicted and observed clearance was 56.9 versus 56.1 (L/h) in HVs. Predicted versus observed mean ± SD area under the curve for extended release felodipine in different severities of CeD were values of 14.5 ± 9.6 versus 14.4 ± 2.1, 14.6 ± 9.0 versus 17.2 ± 2.8, and 28.1 ± 13.5 versus 25.7 ± 5.0 (ng.h/mL), respectively. Accounting for physiology differences in a CeD population accurately predicted the PK of felodipine. The developed CeD population can be applied for determining the drug concentration of CYP3A substrates in the gut as well as for systemic levels, and for application in drug-drug interaction studies.
Topics: Humans; Felodipine; Cytochrome P-450 CYP3A; Celiac Disease; Drug Interactions; Cytochrome P-450 CYP3A Inhibitors; Models, Biological
PubMed: 36855819
DOI: 10.1002/psp4.12954 -
Effects of some antihypertensive drugs on the metabolism and pharmacokinetics of indapamide in rats.Journal of Pharmacy & Pharmaceutical... 2012Indapamide, a non-thiazide antihypertensive diuretic agent, has been widely coadministered with other classes of antihypertensive agents to reach target systolic blood...
PURPOSE
Indapamide, a non-thiazide antihypertensive diuretic agent, has been widely coadministered with other classes of antihypertensive agents to reach target systolic blood pressure. Indapamide is extensively metabolized by cytochromes P450. Interaction of indapamide and other antihypertensive drugs are unknown. We investigated the effects of other antihypertensive drugs on the metabolism and pharmacokinetics of indapamide in vitro and in vivo.
METHODS
Indapamide metabolism was studies in vitro using human liver microsomes pretreated with or without different concentrations of CYP-selective inhibitors and seven major antihypertensive drugs, felodipine, nifedipine, nitrendipine, telmisartan, irbesartan, valsartan and puerarin. Furthermore, the pharmacokinetics of indapamide was determined by HPLC-MS/MS to evaluate the effects of felodipine coadministered on the bioavailability of indapamide in rats in vivo.
RESULTS
The Km and Vmax of indapamide metabolism were 114.35 ± 3.47 μM and 23.13 ± 6.61 μmol/g/min. The metabolites of indapamide, hydroxyl-indapamide and dehydrogen-indapamide, were followed. CYP3A4 and CYP2C19 were involved in indapamide metabolism in human live microsomes. In addition, felodipine, nifedipine and nitrendipine significantly inhibited indapamide metabolism with the maximum inhibitory rates of 82.6%, 72% and 95%, respectively. Felodipine significantly elevated indapamide plasma concentration and prolonged its half-life.
CONCLUSIONS
Combination therapy of indapamide and felodipine might lead to the alteration of indapamide metabolism and pharmacokinetics. The consequence of such an interaction that may include increased effectiveness and side effect needs to be tudeis in human.
Topics: Animals; Antihypertensive Agents; Cytochrome P-450 Enzyme Inhibitors; Diuretics; Drug Interactions; Enzyme Inhibitors; Humans; Indapamide; Male; Microsomes, Liver; Rats; Rats, Sprague-Dawley
PubMed: 22579001
DOI: 10.18433/j3sk5v -
The Chinese herb Styrax triggers pharmacokinetic herb-drug interactions inhibiting intestinal CYP3A.Frontiers in Pharmacology 2022Human cytochrome P450 3A4 (hCYP3A4) is a predominant enzyme to trigger clinically relevant drug/herb-drug interactions (DDIs or HDIs). Although a number of herbal...
Human cytochrome P450 3A4 (hCYP3A4) is a predominant enzyme to trigger clinically relevant drug/herb-drug interactions (DDIs or HDIs). Although a number of herbal medicines have been found with strong anti-hCYP3A4 effects , the modulatory effects of herbal medicines on hCYP3A4 and their potential risks to trigger HDIs are rarely investigated. Herein, we demonstrate a case study to efficiently find the herbal medicine(s) with potent hCYP3A4 inhibition and to accurately assess the potential HDIs risk Following screening over 100 herbal medicines, the Chinese herb Styrax was found with the most potent hCYP3A4 inhibition in HLMs. assays demonstrated that Styrax could potently inhibit mammalian CYP3A in liver and intestinal microsomes from both humans and rats. pharmacokinetic assays showed that Styrax (i.g., 100 mg/kg) significantly elevated the plasma exposure of two CYP3A-substrate drugs (midazolam and felodipine) when midazolam or felodipine was administered orally. By contrast, the plasma exposure of either midazolam or felodipine was hardly affected by Styrax (i.g.) when the victim drug was administered intravenously. Further investigations demonstrated that seven pentacyclic triterpenoid acids (PTAs) in Styrax were key substances responsible for CYP3A inhibition, while these PTAs could be exposed to intestinal tract at relatively high exposure levels but their exposure levels in rat plasma and liver were extremely low. These findings well explained why Styrax (i.g.) could elevate the plasma exposure of victim drugs only when these agents were orally administrated. Collectively, our findings demonstrate that Styrax can modulate the pharmacokinetic behavior of CYP3A-substrate drugs inhibiting intestinal CYP3A, which is very helpful for the clinical pharmacologists to better assess the HDIs triggered by Styrax or Styrax-related herbal products.
PubMed: 36110541
DOI: 10.3389/fphar.2022.974578 -
Current Therapeutic Research, Clinical... Jul 2003In the past decade, many studies have indicated that the combination of low doses of different classes of antihypertensive agents may be more efficacious than...
BACKGROUND
In the past decade, many studies have indicated that the combination of low doses of different classes of antihypertensive agents may be more efficacious than monotherapy while minimizing the likelihood of dose-dependent adverse effects (AEs).
OBJECTIVE
The aim of this study was to determine whether combination therapy with lower doses of candesartan and a calcium antagonist, felodipine, would be more effective and tolerable in controlling mild to moderate hypertension compared with either drug used alone.
METHODS
In this 18-week, single-center, double-blind, crossover study, patients with mild to moderate essential hypertension were randomized to 1 of 2 treatment groups after a 2-week placebo washout period. Patients in group 1 received candesartan 16 mg once daily and patients in group 2 received felodipine 5 mg once daily, for 6 weeks. All patients then received half-dose combination therapy (candesartan 8 mg plus felodipine 2.5 mg, once daily) for 6 weeks. Finally, patients received 6 weeks of monotherapy with the alternate medication (group 1 received felodipine 5 mg once daily and group 2 received candesartan 16 mg once daily).
RESULTS
Thirty patients (18 men, 12 women; mean [SD] age, 54.0 [4.9] years; range, 39-62 years) were included in the study. During both monotherapy periods, candesartan and felodipine significantly reduced blood pressure (BP) (both P<0.001). BP further decreased with combination therapy (P<0.001 in both groups). Overall, 90.0% (27/30) of the patients achieved the target BP at the end of combination therapy. The incidence of AEs was similar with combination therapy compared with either monotherapy.
CONCLUSIONS
In this study population, candesartan and felodipine had additive effects when used in combination, even at low doses, in the treatment of hypertension. Therefore, the combination of candesartan and felodipine is an effective alternative to that of candesartan and hydrochlorothiazide.
PubMed: 24944389
DOI: 10.1016/S0011-393X(03)00128-0 -
British Journal of Pharmacology Aug 19941. The ability of two dihydropyridine calcium channel antagonists, felodipine and nitrendipine both to displace [3H]-isradipine binding in CNS tissue measured ex vivo...
1. The ability of two dihydropyridine calcium channel antagonists, felodipine and nitrendipine both to displace [3H]-isradipine binding in CNS tissue measured ex vivo and to protect against the ethanol withdrawal syndrome has been investigated. 2. Mice were injected with various doses of felodipine or nitrendipine and [3H]-isradipine binding measured in brain homogenates prepared 0.5, 3 or 5 h later. Inhibition versus dose curves were sigmoid and the dose required to produce 50% inhibition increased linearly with time after administration. Felodipine was approximately 10 times more potent than nitrendipine. 3. Nitrendipine (50 mg kg-1, i.p.) and felodipine (10 mg kg-1, i.p.) produced around a 75% inhibition of [3H]-isradipine binding 3 h later. Binding of [3H]-nitrendipine to cerebral tissues measured after in vivo injection of the ligand was decreased by nitrendipine (50 mg kg-1) and felodipine (10 mg kg-1) to a similar extent. 4. Nitrendipine (50 mg kg-1) prevented the behavioural signs of ethanol withdrawal as measured by handling induced convulsions, but felodipine (10 mg kg-1 or 2 mg kg-1) did not provide any protection against this effect of ethanol withdrawal. Felodipine (10 mg kg-1, twice daily) during the course of ethanol treatment also failed to attenuate the withdrawal syndrome. 5. The convulsive response to a mild audiogenic stimulus during ethanol withdrawal was increased following one dose of felodipine (5 mg kg-1, i.p.) but unaffected by nitrendipine. 6. Injection of Bay K 8644 (60 microgram, i.c.v.) produced a significant increase in handling-induced convulsive behaviour. Felodipine (10 mg kg-1, i.p.) reduced this behaviour both 60 and 120 min later, while nitrendipine (50 mg kg-1) showed a modest reduction only at 120 min.7. In contrast, nitrendipine (50mg kg-1) and felodipine (10 mg kg-1) produced similar effects on the hyperexcitability produced by handling following administration of bicuculline. Hexamethonium(8 mg kg-1) had no effect on this response.8. No change was found in [3H]-isradipine or [125I]-w-conotoxin binding to cerebral tissue prepared from ethanol-dependent mice.9. These results demonstrate that while felodipine and nitrendipine have similar actions on some CNS-mediated effects (raising seizure thresholds to several convulsant drugs), felodipine, in contrast to nitrendipine, has no effect on the ethanol withdrawal syndrome. Suggested explanations for the results include the possibility that nitrendipine may protect against the ethanol withdrawal syndrome via sites other than dihydropyridine receptors: that felodipine has partial agonist actions at dihydropyridine receptors in the CNS or that felodipine has actions which mask its protective effect in ethanol withdrawal.
Topics: 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; Animals; Bicuculline; Binding Sites; Brain; Ethanol; Felodipine; Isradipine; Male; Mice; Nitrendipine; Substance Withdrawal Syndrome
PubMed: 7524989
DOI: 10.1111/j.1476-5381.1994.tb13184.x -
Pharmaceutics Feb 2023Dihydropyridine drugs are well known as photodegradable pharmaceuticals. Herein, we evaluate the photostability of felodipine (FL) medicine (Splendil (SPL) tablets) and...
Dihydropyridine drugs are well known as photodegradable pharmaceuticals. Herein, we evaluate the photostability of felodipine (FL) medicine (Splendil (SPL) tablets) and its altered forms (powders and suspensions). FL is a type of dihydropyridine drug, but its photochemical behavior is unknown. FL contents after ultraviolet light (UV) irradiation for 24 h were monitored using high-performance liquid chromatography (HPLC). Values of the residual amounts of FL in UV-irradiated SPL powders and suspensions were 32.76 ± 4.88% and 0.79 ± 0.74%, respectively, with the generation of two photoproducts (FL photoproduct 1 and 2). To identify the chemical structures of these photoproducts, electrospray ionization liquid chromatography mass spectrometry (ESI-LC/MS/MS) analysis was performed. Based on their mass-to-charge ratio values and fragment patterns, it was proposed that FL photoproduct 1 was a pyridine derivative and FL photoproduct 2 was an FL dimer. Interestingly, generation rates of FL photoproduct 1 and 2 were dependent on the presence of the aqueous media. The photodimerization of FL was induced in UV-irradiated SPL suspensions. This is the first report evaluating the photostability of SPL tablets and its altered forms and estimating FL photoproducts induced by UV irradiation in the formulation of SPL.
PubMed: 36840019
DOI: 10.3390/pharmaceutics15020697 -
British Journal of Clinical Pharmacology Jan 19911. The pharmacokinetics of felodipine was studied after continuous oral administration of 5 or 10 mg conventional tablets to a population of 140 male and female...
1. The pharmacokinetics of felodipine was studied after continuous oral administration of 5 or 10 mg conventional tablets to a population of 140 male and female Caucasian subjects, of which 67 were hypertensive patients and 73 were healthy volunteers. In addition, 42 of these individuals received felodipine intravenously. 2. With increasing age the area under the felodipine plasma concentration vs time curve (AUC), the maximum plasma concentration (Cmax), and the terminal elimination half-life of felodipine increased, while the plasma clearance of felodipine decreased. The bioavailability and steady state volume of distribution and the time to Cmax were not consistently influenced by age. 3. The ratio of the AUC of the primary pyridine metabolite of felodipine and that of unchanged drug decreased with increasing age. 4. Neither Cmax, AUC nor the half-life of felodipine were related to body mass index. 5. The distribution of AUC for felodipine, as well as the ratio of the AUC of this first metabolite to that of unchanged felodipine, was unimodal. Thus, the presence of a sizable group of individuals, with a clinically significant different metabolism of 1,4-dihydropyridine due to genetic factors is unlikely. 6. The pharmacokinetics of felodipine did not seem to differ between hypertensive patients and healthy volunteers, when adjusted for age. Neither was there a difference between patients taking beta-adrenoceptor antagonists and those who did not. 7. As a group the elderly had higher total concentrations of unchanged felodipine in plasma compared with younger individuals. The variation in plasma concentrations of felodipine between individuals is, however, only partially explained by age. In clinical practice this emphasizes the need for dose titration of felodipine.
Topics: Adult; Aged; Aged, 80 and over; Aging; Antihypertensive Agents; Body Weight; Drug Interactions; Felodipine; Female; Half-Life; Humans; Male; Middle Aged; Polymorphism, Genetic; Sex Factors
PubMed: 2015166
DOI: 10.1111/j.1365-2125.1991.tb03852.x -
Journal of Clinical Hypertension... Jan 2006
Topics: Aged; Antihypertensive Agents; Blood Pressure Determination; Clonidine; Felodipine; Female; Humans; Hypertension; Male
PubMed: 16407692
DOI: 10.1111/j.1524-6175.2005.05145.x