Prediction of Plasma Drug Concentration Profiles and Pharmacokinetic Parameters of Nifedipine Commercial Tablets using the Convolution Method

The aim of this study was to predict the blood/plasma drug concentration profiles for five brand of nifedipine present on the Saudi Arabia market by using the numerical convolution method and to estimate the pharmacokinetic parameters (Cmax, Tmax, Ka, K and Vd) by the application of the residual method to the predicted plasma drug concentration profiles. Results showed that the higher Cmax was 118.95ng/ml for brand A2 and the lower Cmax was 72.29ng/ml for brand A3. The Tmax was ranged from 2.3 hr to 4.9 hr for brands A2 and A3 respectively. The total area under plasma drug concentration curve (AUCinf.) was in lower value equal to 585.59 ng x hr/ml for brand A2 and the higher value was for brand A5 equal to 743.52ng x hr/ml. The volume of distribution was also increased from 52.5 L for free nifidipine to 72 L for brand A1. The predicted first order elimination rate constant was decreased from 0.34 hr-1 for free nifedipine to 0.17 hr-1 for brand A3. The half-life of nifedapine was increased from 2 hours for free drug to 3.93 hours for brand A3. From this study it can be concluded that brands present in the market that shows similarity in accordance to the Dissimilarity factor f1 are not always guaranty that they will be bioequivalent in vivo and vice versa. Also, this study indicates that the method of convolution is a useful tool for prediction of bioequivalence of different brands present on the market.

ALTERATION OF PHARMACOKINETIC PARAMETERS OF PROTON PUMP INHIBITORS USING TRANSDERMAL DRUG DELIVERY SYSTEM

Objective: The present study was aimed to find out the effect of transdermal patches of proton pump inhibitors pantoprazole and esomeprazole on the alteration of pharmacokinetic parameters of these drugs. Methods: The transdermal patches were formulated by the solvent evaporation technique using polymers HPMC E5 with PVP K 30 and HPMC E5 with Eudragit L100 in different ratios. The best formulation from each of the drug pantoprazole and esomeprazole was selected and administered to rabbits and the plasma drug concentration was compared with the marketed formulation. The pharmacokinetic parameters such as maximum plasma concentration (Cmax), time to reach Cmax (tmax), area under the curve (AUC), area under first moment curve (AUMC), elimination rate constant (λz), biological half-life (t1/2), and mean residence time (MRT) were determined. Results: The plasma drug concentration vs time curve shows the extended-release of the drugs pantoprazole and esomeprazole when compared with the marketed formulation. The results show that there is no change in the peak plasma concentration, but a significant difference was observed in all the pharmacokinetic parameters. The AUC showed 6 fold increase for pantoprazole from 8.91 to 55.20 μg*h/ml and 3.5 fold increase for the drug esomeprazole from 7.86 to 28.53 μg*h/ml, and the mean residence time also showed 2 fold increase for the transdermal patches when compared with the marketed formulations. Conclusion: The increase in tmax, AUC, and MRT values of the formulated transdermal patches with the values of the marketed formulation of both the drugs, revealed that the transdermal patches can be used to deliver the drug for an extended period and also can alter the pharmacokinetics of pantoprazole and esomeprazole.

Lipid Based Drug Delivery System: A Review

Associated with the old/traditional of method of drug delivery are several limitation ranging from first-pass effect, low tolerance, minimal bioavailability, fluctuation of plasma drug concentration which result to less or no desired effect produced. This call for the demand for a more efficient drug administration technique. Lipid systems are biocompatible, inert and biodegradable, stable and deliver at the target with the desired effect. This paper attempt to describe several types of lipid particles used to deliver drug compounds and their applications as therapeutic agent in treating different clinical condition.

Caution in Using the Activated Partial Thromboplastin Time to Monitor Argatroban in COVID-19 and Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT)

Introduction Argatroban is licensed for patients with heparin-induced thrombocytopenia and is conventionally monitored by activated partial thromboplastin time (APTT) ratio. The target range is 1.5 to 3.0 times the patients’ baseline APTT and not exceeding 100 s, however this baseline is not always known. APTT is known to plateau at higher levels of argatroban, and is influenced by coagulopathies, lupus anticoagulant and raised FVIII levels. It has been used as a treatment for COVID-19 and Vaccine-induced Immune Thrombocytopenia and Thrombosis (VITT). Some recent publications have favored the use of anti-IIa methods to determine the plasma drug concentration of argatroban. Methods Plasma of 60 samples from 3 COVID-19 patients and 54 samples from 5 VITT patients were tested by APTT ratio and anti-IIa method (dilute thrombin time dTT). Actin FS APTT ratios were derived from the baseline APTT of the patient and the mean normal APTT. Results Mean APTT ratio derived from baseline was 1.71 (COVID-19), 1.33 (VITT) compared to APTT ratio by mean normal 1.65 (COVID-19), 1.48 (VITT). dTT mean concentration was 0.64 µg/ml (COVID-19) 0.53 µg/ml (VITT) with poor correlations to COVID-19 baseline APTT ratio r2 = 0.1526 p <0.0001, mean normal r2 = 0.2188 p < 0.0001; VITT baseline APTT ratio r2 = 0.04 p < 0.001, VITT mean normal r2 = 0.0064 p < 0.001. Conclusions We believe that dTT is a superior method to monitor the concentration of argatroban, we have demonstrated significant differences between APTT ratios and dTT levels, which could have clinical impact. This is especially so in COVID-19 and VITT.

Benefits of Therapeutic Drug Monitoring of First Line Antituberculosis Drugs

Tuberculosis is an airborne infectious disease that remains a huge global health-related issue nowadays. Despite constant approvals of newly developed drugs, the use of first-line antituberculosis medicines seems reasonable in drug-susceptible Mycobacterium tuberculosis strains. Therapeutic drug monitoring presents a useful technique for the determination of plasma drug concentration to adjust appropriate dose regimes. In tuberculosis treatment, therapeutic drug monitoring is aiding clinicians in selecting an optimal therapeutic level, which is essential for the personalisation of therapy. This review is aimed at clarifying the use of therapeutic drug monitoring of the first-line antituberculosis drugs in routine clinical practice.

Prospective observational study on the pharmacokinetic properties of the Irrua ribavirin regimen used in routine clinical practice in patients with Lassa fever in Nigeria

IntroductionLassa fever (LF) is a severe and often fatal systemic disease in humans and affects a large number of countries in West Africa. Treatment options are limited to supportive care and the broad-spectrum antiviral agent ribavirin. However, evidence for ribavirin efficacy in patients with LF is poor and pharmacokinetic (PK) data are not available.Irrua Specialist Teaching Hospital (ISTH) developed an intravenous ribavirin regimen different to the WHO recommendation. Apart from a lower total daily dose the drug is usually administered once per day which reduces the exposure of personnel to patients with LF. The aim of this study is to characterise the PK of the Irrua ribavirin regimen.Methods and analysisThis prospective, observational clinical study will assess PK properties of the Irrua ribavirin regimen on routinely ribavirin-treated patients with LF at ISTH, a referral hospital serving 19 local governmental areas in a LF endemic zone in Nigeria. Participants will be adults with PCR-confirmed LF. The primary objective is to describe classical PK parameters for ribavirin (maximum plasma drug concentration, time to maximum plasma drug concentration, area under the plasma drug concentration vs time curve, half-life time T1/2, volume of distribution). Blood samples will be collected at 0.5, 1, 3, 5, 8, 12 and 24 hours after doses on day 1, day 4 and day 10 of ribavirin treatment. Ribavirin plasma concentrations will be determined using liquid chromatography coupled to tandem mass spectrometry.Ethics and disseminationThe study will be conducted in compliance with the protocol, the Declaration of Helsinki, Good Clinical Practice (GCP) and the Nigerian National Code for Health Research Ethics. The protocol has received approval by the Health Research Ethics Committee of ISTH. Results will be made available to LF survivors, their caregivers, the funders, LF research society and other researchers.Registration detailsISRCTN11104750

Evaluation of the pharmacokinetic interaction and safety of ubrogepant coadministered with acetaminophen or nonsteroidal anti-inflammatory drugs: A randomized trial

Background: Ubrogepant is a novel, oral calcitonin gene–related peptide receptor antagonist approved by the US Food and Drug Administration for acute treatment of migraine with or without aura in adults. Objectives: To assess potential pharmacokinetic (PK) drug–drug interactions in healthy participants and inform the safety and tolerability of ubrogepant alone and in combination with acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) in healthy participants and participants with migraine. Methods: Two phase 1, three-way crossover studies randomized healthy adults to 100 mg ubrogepant alone, 1000 mg acetaminophen or 500 mg naproxen alone, and 100 mg ubrogepant plus 1000 mg acetaminophen or 500 mg naproxen. Geometric mean ratios (GMRs) and 90% confidence intervals were calculated based on statistical comparison of maximum plasma drug concentration ( C max) and area under the plasma drug concentration–time curve (AUC) for treatment in combination versus alone. Two phase 3 randomized trials included adults with migraine. Treatment-emergent adverse events (TEAEs) were evaluated. Results: Time to C max and terminal elimination half-life for all treatments were unchanged when coadministered. Ubrogepant C max and AUC increased by approximately 40% when coadministered with acetaminophen. Acetaminophen C max decreased by 24% (GMR = 0.76) when coadministered with ubrogepant. There were no significant PK interactions between ubrogepant and naproxen. TEAE rates in the acetaminophen and NSAID rescue medication groups were similar to ubrogepant alone. Conclusions: Coadministration of ubrogepant and acetaminophen resulted in a statistically significant increase in ubrogepant exposure and a decrease in acetaminophen C max; however, these changes were not clinically relevant. No statistically or clinically relevant changes in PK were associated with ubrogepant and naproxen coadministration. No safety concerns were identified for ubrogepant alone or in combination with acetaminophen or NSAIDs.

Evaluation of Pharmacokinetic Interaction of Cilostazol with Metoclopramide after Oral Administration in Human

Background: Metoclopramide is mainly metabolized by CYP2D6, CYP3A4, CYP2C19, and CYP1A2 enzymes, while cilostazol is also metabolized by CYP3A4, CYP2C19, and CYP1A2 enzymes. Aim: This study evaluates the effect of cilostazol on the pharmacokinetics of oral metoclopramide. Methods: This was a randomized, two-phase cross-over pharmacokinetic study separated by a 4-week wash-out time period, 12 healthy non-smoking volunteers received metoclopramide 20 mg as a single oral dose and after 4 weeks, cilostazol 100 mg twice daily for 4 days then with metoclopramide 20 mg on test day. Serial blood samples were analyzed by using a validated high-performance liquid chromatography-ultraviolet method to determine maximum plasma drug concentration (Cmax), time to reach (Tmax), and area under the curve (AUC0-∞) of metoclopramide. Results: Cilostazol increased the mean Cmax, AUC0-∞ and half-life (T1/2) of metoclopramide by 6%, 27% and by 0.79 %, respectively. In addition, Tmax of metoclopramide was delayed by cilostazol. Conclusion: The results showed delayed Tmax of metoclopramide by cilostazol, which could lead to the conclusion that cilostazol affects the absorption of metoclopramide. Both drugs when necessary to administer together must not be administered at the same time especially when given in gastroparesis patients.

ALTERATION OF PHARMACOKINETIC PARAMETERS OF PENTOXIFYLLINE USING NATURAL MUCOADHESIVE POLYMERS

Objective: The present study was aimed to alter the pharmacokinetic parameters of the drug pentoxifylline using a novel natural mucoadhesive polymer from two different plants, Manilkara zapotta Linn and Ocimum basilicum Linn. Methods: The polymer was isolated and six batches of mucoadhesive tablets of pentoxifylline was formulated with 3 different concentrations of each polymer. The best formulation from each of the polymer was selected and administered to rabbits and the plasma drug concentration was compared with the marketed formulation. The pharmacokinetic parameters such as such as Cmax, tmax, AUC, AUMC, λz, t1/2, and MRT were determined. Results: The plasma drug concentration vs time curve shows the extended-release of pentoxifylline when compared with the conventional marketed formulation. The results show that there is no change in the peak plasma concentration, but the significant difference was observed in t½, which showed approximately 2.5 fold increase from 2.44 to 6.87 h and the AUC showed five-fold increase from 22.40 to 117.19 μg*h/ml, and other pharmacokinetic parameters, when compared with the marketed formulation. Conclusion: The isolated polymer from the plants Manilkara zapotta Linn. and Ocimum basilicum Linn can be used as a carrier for developing mucoadhesive formulations and it alter the pharmacokinetic of pentoxifylline positively.