Pharmacokinetics of Coadministered Guanfacine Extended Release and Lisdexamfetamine Dimesylate

Background

In clinical practice, α₂-adrenoceptor agonists have been adjunctively administered with psychostimulants for the treatment of attention-deficit/hyperactivity disorder (ADHD). Two studies have examined the adjunctive use of guanfacine extended release (GXR, Intuniv^®; Shire Development LLC, Wayne, PA, USA) with psychostimulants in children and adolescents with a suboptimal response to psychostimulant treatment. However, the potential for pharmacokinetic drug–drug interactions (DDIs) between GXR and lisdexamfetamine dimesylate (LDX, Vyvanse^®; Shire US LLC, Wayne, PA, USA) has not been thoroughly evaluated.

Objective

The primary objective of this study was to examine the pharmacokinetics of GXR 4 mg and LDX 50 mg given as single doses alone and in combination.

Study Design

This was an open-label, randomized, three-period crossover, DDI study.

Setting

The study was conducted in a single clinical research center.

Participants

Forty-two healthy adults were randomized in this study.

Interventions

Subjects were administered single oral doses of GXR 4 mg, LDX 50 mg, or GXR and LDX in combination.

Main Outcome Measures

Blood samples collected predose and up to 72 h postdose assessed guanfacine, LDX, and d-amphetamine levels. Bioequivalence was defined as the 90 % confidence intervals (CIs) of the geometric mean ratios of the area under the plasma concentration–time curve extrapolated to infinity (AUC_0–∞) and maximum plasma concentration (C_max) falling within the bioequivalence reference interval (0.80–1.25). Safety measures included adverse events, vital signs, and electrocardiograms (ECGs).

Results

Forty subjects completed the study. Following administration of LDX alone or in combination with GXR, the statistical comparisons of the AUC_0–∞ and C_max of d-amphetamine fell entirely within the reference interval. For guanfacine, the 90 % CI of the geometric mean ratio of AUC_∞ for the two treatments was within the bioequivalence criteria, but for C_max the upper bound of the 90 % CI exceeded the standard range for bioequivalence by 7 %. This relatively small change is unlikely to be clinically meaningful. Treatment-emergent adverse events (TEAEs) were reported by 42.9 % of subjects; the most commonly reported TEAEs included dizziness (5.0, 7.3, and 7.3 %) and headache (7.5, 4.9, and 7.3 %) following administration of GXR, LDX, and GXR and LDX in combination, respectively. Clinically significant ECG abnormalities occurred in one subject following administration of LDX and in one subject following coadministration of GXR and LDX.

Conclusions

In healthy adults, coadministration of GXR and LDX did not result in a clinically meaningful pharmacokinetic DDI compared with either treatment alone. No unique TEAEs were observed with coadministration of GXR and LDX compared with either treatment alone.     

The Safety of Besifloxacin Ophthalmic Suspension 0.6?% Used Three Times Daily for 7?Days in the Treatment of Bacterial Conjunctivitis

Background

Besifloxacin ophthalmic suspension 0.6 % (Besivance^®; Bausch & Lomb, Rochester, NY, USA) was approved by the FDA in 2009 for the treatment of bacterial conjunctivitis, with a recommended 7-day dosing regimen.

Objective

The objective of this study was to compare the safety of besifloxacin ophthalmic suspension 0.6 %, administered three times a day for 7 days, with that of its vehicle.

Methods

This randomized, multicenter, double-masked, vehicle-controlled, parallel-group study involved 518 patients ≥1 year of age with a clinical diagnosis of bacterial conjunctivitis. Patients were randomized 2:1 to treatment with besifloxacin 0.6 % ophthalmic suspension or vehicle, one drop in the infected eye(s) TID for 7 days. Main outcomes included the incidence and types of adverse events reported by the subject or observed by the investigator at each study visit.

Results

Thirty-one ocular treatment-emergent adverse events (TEAEs) were reported by 28 subjects in the study eye; 19 occurred in 17/344 (4.9 %) besifloxacin patients, and 12 occurred in 11/170 (6.5 %) vehicle patients (p = 0.5362). Only two ocular events (mild instillation site reaction, one case in each group) were considered “definitely related” to study treatment. One event of self-limited dysgeusia in the besifloxacin group was considered definitely related to treatment; there were no other nonocular TEAEs considered related to treatment. There were no serious adverse events, and other safety outcomes (visual acuity, biomicroscopy, ophthalmoscopy) were unremarkable.

Conclusion

These findings indicate that besifloxacin ophthalmic suspension 0.6 % is safe in patients aged 1 year and older when used TID for 7 days.     

Pharmacokinetic interactions and safety evaluations of coadministered tafenoquine and chloroquine in healthy subjects

Aims

The long-acting 8-aminoquinoline tafenoquine (TQ) coadministered with chloroquine (CQ) may radically cure Plasmodium vivax malaria. Coadministration therapy was evaluated for a pharmacokinetic interaction and for pharmacodynamic, safety and tolerability characteristics.

Methods

Healthy subjects, 18–55 years old, without documented glucose-6-phosphate dehydrogenase deficiency, received CQ alone (days 1–2, 600 mg; and day 3, 300 mg), TQ alone (days 2 and 3, 450 mg) or coadministration therapy (day 1, CQ 600 mg; day 2, CQ 600 mg + TQ 450 mg; and day 3, CQ 300 mg + TQ 450 mg) in a randomized, double-blind, parallel-group study. Blood samples for pharmacokinetic and pharmacodynamic analyses and safety data, including electrocardiograms, were collected for 56 days.

Results

The coadministration of CQ + TQ had no effect on TQ AUC_0–t, AUC_0–∞, T_max or t_1/2. The 90% confidence intervals of CQ + TQ vs. TQ for AUC_0–t, AUC_0–∞ and t_1/2 indicated no drug interaction. On day 2 of CQ + TQ coadministration, TQ C_max and AUC_0–24 increased by 38% (90% confidence interval 1.27, 1.64) and 24% (90% confidence interval 1.04, 1.46), respectively. The pharmacokinetics of CQ and its primary metabolite desethylchloroquine were not affected by TQ. Coadministration had no clinically significant effect on QT intervals and was well tolerated.

Conclusions

No clinically significant safety or pharmacokinetic/pharmacodynamic interactions were observed with coadministered CQ and TQ in healthy subjects.     

Translational pharmacokinetic–pharmacodynamic modelling; application to cardiovascular safety data for PF-00821385, a novel HIV agent

AIM

To assess the translation of pharmacokinetic–pharmacodynamic (PK–PD) relationships for heart rate effects of PF-00821385 in dog and man.

METHODS

Cardiovascular telemetric parameters and concentration data were available for animals receiving active doses (0.5–120 mg kg⁻¹, n= 4) or vehicle. PF-00821385 was administered to 24 volunteers and pharmacokinetic and vital signs data were collected. PK–PD models were fitted using nonlinear mixed effects.

RESULTS

Compartmental models with linear absorption and clearance were used to describe pharmacokinetic disposition in animal and man. Diurnal variation in heart and pulse rate was best described with a single cosine function in both dog and man. Canine and human heart rate change were described by a linear model with free drug slope 1.76 bpm µM⁻¹[95% confidence interval (CI) 1.17, 2.35] in the dog and 0.76 bpm µM⁻¹ (95% CI 0.54, 1.14) in man.

CONCLUSIONS

The preclinical translational of concentration–response has been described and the potential for further interspecies extrapolation and optimization of clinical trial design is addressed.     

Serum Concentration of Lignocaine After Pertubation: An Observational Study

Objective

The objective of this study was to report the serum concentration of lignocaine after pertubation in patients with endometriosis.

Design

Prospective observational study.

Setting

The study was carried out at a gynaecological outpatient unit in Stockholm, Sweden.

Population

Eligible patients had endometriosis with a dysmenorrhoic pain score of >50 mm on a visual analogue scale, and patent fallopian tubes.

Methods

Patients with endometriosis (n = 25) were included in the study. The patients received pre-ovulatory pertubations with lignocaine hydrochloride 10 mg (n = 16) or ringer acetate (placebo, n = 9). The procedure comprised passing the study solution through the uterus and the fallopian tubes via an intra-cervical balloon catheter. Serum samples were collected at 0, 5, 15 and 30 min after pertubation.

Main Outcome Measures

The serum samples were analysed for the concentration of lignocaine with an LCMS-SIM method.

Results

Low levels of lignocaine were detected in the serum samples following pertubation of 10 mg lignocaine hydrochloride. The highest observed concentration was seen after 30 min (mean 0.050 μg/ml), with an individual maximum of 0.124 μg/ml. Maximum concentration (C_max) and time to C_max (T_max) could not be calculated, since the highest values were observed in the 30-min samples, which was the last sample obtained. Lignocaine was not detected after pertubation with placebo.

Conclusions

The serum levels of lignocaine following pertubation of 10 mg lignocaine hydrochloride are detectable but low. Lignocaine pertubated through the fallopian tubes reaches the peritoneal cavity and diffuses through the peritoneum into the blood circulation. Pertubation with lignocaine is safe and has no lignocaine-related adverse events.     

Pharmacokinetic tools for the dose adjustment of ciclosporin in haematopoietic stem cell transplant patients

Aims

Ciclosporin A (CsA) is used in the prophylaxis and treatment of acute and chronic graft vs. host disease after haematopoietic stem cell (HSCT) transplantation. Our objective was to build and compare three independent Bayesian estimators of CsA area under the curve (AUC) using a limited sampling strategy (LSS), to assist in dose adjustment.

Methods

The Bayesian estimators were developed using in parallel: two independent parametric modelling approaches (nonmem® and iterative two stage (ITS) Bayesian modelling) and the non-parametric adaptive grid method (Pmetrics®). Seventy-two full pharmacokinetic profiles (at pre-dose and 0.33, 0.66, 1, 2, 3, 4, 6, 8 and 12h after dosing) collected from 40 HSCT patients given CsA were used to build the pharmacokinetic models, while 15 other profiles (n = 7) were kept for validation. For each Bayesian estimator, AUCs estimated using the full profiles were compared with AUCs estimated using three samples.

Results

The pharmacokinetic profiles were well fitted using a two compartment model with first order elimination, combined with a gamma function for the absorption phase with ITS and Pmetrics or an Erlang distribution with nonmem. The derived Bayesian estimators based on a C0-C1 h-C4 h sampling schedule (best LSS) accurately estimated CsA AUC(0,12 h) in the validation group (n = 15; nonmem: bias (mean ± SD)/RMSE 2.05% ± 13.31%/13.02%; ITS: 4.61% ± 10.56%/11.20%; Pmetrics: 0.30% ± 10.12%/10.47%). The dose chosen confronting the three results led to a pertinent dose proposal.

Conclusions

The developed Bayesian estimators were all able to predict ciclosporin AUC(0,12 h) in HSCT patients using only three blood with minimal bias and may be combined to increase the reliability of CsA dose adjustment in routine.     

The effect of Echinacea purpurea on the pharmacokinetics of docetaxel

Aims

The herbal medicine Echinacea purpurea (E. purpurea) has been shown to induce cytochrome P450 3A4 (CYP3A4) both in vitro and in humans. This study explored whether E. purpurea affects the pharmacokinetics of the CYP3A4 substrate docetaxel in cancer patients.

Methods

Ten evaluable cancer patients received docetaxel (135 mg, 60 min IV infusion) before intake of a commercially available E. purpurea extract (20 oral drops three times daily) and 3 weeks later after a 14 day supplementation period with E. purpurea. In both cycles, pharmacokinetic parameters of docetaxel were determined.

Results

Before and after supplementation with E. purpurea, the mean area under the plasma concentration–time curve of docetaxel was 3278 ± 1086 and 3480 ± 1285 ng ml⁻¹ h, respectively. This result was statistically not significant. Nonsignificant alterations were also observed for the elimination half-life (from 30.8 ± 19.7 to 25.6 ± 5.9 h, P = 0.56) and maximum plasma concentration of docetaxel (from 2224 ± 609 to 2097 ± 925 ng ml⁻¹, P = 0.30).

Conclusions

The multiple treatment of E. purpurea did not significantly alter the pharmacokinetics of docetaxel in this study. The applied E. purpurea product at the recommended dose may be combined safely with docetaxel in cancer patients.     

Inhibition of oral midazolam clearance by boosting doses of ritonavir,and by 4,4-dimethyl-benziso-(2H)-selenazine (ALT-2074), an experimental catalytic mimic of glutathione oxidase

AIMS

We evaluated whether ‘boosting’ doses of ritonavir can serve as a positive control inhibitor for pharmacokinetic drug–drug interaction studies involving cytochrome P450 3A (CYP3A). The study also determined whether 4,4-dimethyl-benziso-(2H)-selenazine (ALT-2074), an investigational organoselenium compound that acts as a catalytic mimic of glutathione oxidase, inhibits CYP3A metabolism in vivo.

METHODS

Thirteen healthy volunteers received single 3-mg oral doses of midazolam on three occasions: in the control condition, during co-treatment with low-dose ritonavir (three oral doses of 100 mg over 24 h), and during co-treatment with ALT-2074 (three oral doses of 80 mg over 24 h).

RESULTS

Ritonavir increased mean (±SE) total area under the curve (AUC) for midazolam by a factor of 28.4 ± 4.2 (P < 0.001), and reduced oral clearance to 4.2 ± 0.5% of control (P < 0.001). In contrast, ALT-2074 increased midazolam AUC by 1.25 ± 0.11 (P < 0.05), and reduced oral clearance to 88 ± 8% of control.

CONCLUSIONS

Low-dose ritonavir produces extensive CYP3A inhibition exceeding that of ketoconazole (typically 10- to 15-fold midazolam AUC enhancement), and is a suitable positive control index inhibitor for drug–drug interaction studies. ALT-2074 inhibits CYP3A metabolism to a small degree that is of uncertain clinical importance.     

Sustained-Release Fampridine (4-Aminopyridine) in Multiple Sclerosis: Efficacy and Impact on Motor Function

Objective

The aim of this study was to determine the efficacy of sustained-release fampridine (4-aminopyridine) in veterans with multiple sclerosis (MS) with limited ambulatory ability, and its impact on motor function in an outpatient setting.

Design

Retrospective.

Setting

Tertiary referral center [Veterans Affairs (VA) Medical Center].

Participants

Veterans; 20 MS patients were prescribed dalfampridine (10 mg twice daily) due to their difficulty with walking based on patient and caregiver report and clinician impression of change in the ability to ambulate based on prior 10-meter (10M) and 2-minute walk tests (2MWTs).

Intervention

Not applicable.

Main Outcome Measures

The primary outcome measures were mean changes in walking speed (10M walk test), walking distance (2MWT), and Total Functional Independence Measure (TFIM). Improvement of >20 % in walking speed was indicated as a clinically meaningful change.

Results

Treatment with dalfampridine resulted in significant improvement in walking speed and endurance (p < 0.05). Walking speed increased by 33 % and walking endurance by 31 %, representing clinically meaningful improvement. This change was not influenced by change in muscle tone. This improvement in mobility was associated with a clinically significant change in motor function. Adverse effects, including insomnia, dizziness, and headache, were experienced by five patients who discontinued the medication after a minimum of 4 weeks.

Conclusion

Treatment with dalfampridine resulted in clinically relevant improvements in walking speed and endurance in MS patients with limited ambulation and helped improve their motor function.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-013-0020-x) contains supplementary material, which is available to authorized users.     

Pharmacokinetic optimization of four soluble epoxide hydrolase inhibitors for use in a murine model of inflammation

Background and purpose:

Early soluble epoxide hydrolase inhibitors (sEHIs) such as 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA) are effective anti-hypertensive and anti-inflammatory agents in various animal models. However, their poor metabolic stability and limited water solubility make them difficult to use pharmacologically. Here we present the evaluation of four sEHIs for improved pharmacokinetic properties and the anti-inflammatory effects of one sEHI.

Experimental approach:

The pharmacokinetic profiles of inhibitors were determined following p.o. (oral) administration and serial bleeding in mice. Subsequently the pharmacokinetics of trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), the most promising inhibitor, was further studied following s.c. (subcutaneous), i.v. (intravenous) injections and administration in drinking water. Finally, the anti-inflammatory effect of t-AUCB was evaluated by using a lipopolysaccharide (LPS)-treated murine model.

Key“ results:

Better pharmacokinetic parameters (higher C_max, longer t_1/2 and greater AUC) were obtained from the tested inhibitors, compared with AUDA. Oral bioavailability of t-AUCB (0.1 mg·kg⁻¹) was 68 ± 22% (n = 4), and giving t-AUCB in drinking water is recommended as a feasible, effective and easy route of administration for chronic studies. Finally, t-AUCB (p.o.) reversed the decrease in plasma ratio of lipid epoxides to corresponding diols (a biomarker of soluble epoxide hydrolase inhibition) in lipopolysaccharide-treated mice. The in vivo potency of 1 mg·kg⁻¹ of t-AUCB (p.o.) was better in this inflammatory model than that of 10 mg·kg⁻¹ of AUDA-butyl ester (p.o) at 6 h after treatment.

Conclusions and implications:

t-AUCB is a potent sEHI with improved pharmacokinetic properties. This compound will be a useful tool for pharmacological research and a promising starting point for drug development.     

Comparative pharmacokinetics of cefuroxime lysine after single intravenous,intraperitoneal, and intramuscular administration to rats

Aim:

To compare the pharmacokinetic parameters of cefuroxime lysine, a new second-generation of cephalosporin antibiotics, after intravenous (IV), intraperitoneal (IP), or intramuscular (IM) administration.

Methods:

Twelve male and 12 virgin female Sprague-Dawley rats, weighing from 200 to 250 g, were divided into three groups (n=4 for each gender in each group). The rats were administered a single dose (67.5 mg/kg) of cefuroxime lysine via IV bolus or IP or IM injection. Blood samples were collected and analyzed with a validated UFLC-MS/MS method. The concentration-time data were then calculated by compartmental and non-compartmental pharmacokinetic methods using DAS software.

Results:

After IV, IP or IM administration, the plasma cefuroxime lysine disposition was best described by a tri-compartmental, bi-compartmental or mono-compartmental open model, respectively, with first-order elimination. The plasma concentration profiles were similar through the 3 administration routes. The distribution process was rapid after IV administration [t_1/2(d), 0.10±0.11 h vs 1.36±0.65 and 1.25±1.01 h]. The AUMC_0–∞ is markedly larger, and mean residence time (MRT) is greatly longer after IP administration than that in IV, or IM routes (AUMC_0–∞: 55.33±20.34 vs 16.84±4.85 and 36.17±13.24 mg·h²/L; MRT: 0.93±0.10 h vs 0.37±0.07 h and 0.65±0.05 h). The C_max after IM injection was significantly higher than that in IP injection (73.51±12.46 vs 49.09±7.06 mg/L). The AUC_0–∞ in male rats were significantly higher than that in female rats after IM administration (66.38±16.5 vs 44.23±6.37 mg·h/L). There was no significantly sex-related difference in other pharmacokinetic parameters of cefuroxime lysine between male and female rats.

Conclusion:

Cefuroxime lysine shows quick absorption after IV injection, a long retension after IP injection, and a high C_max after IM injection. After IM administration the AUC_0–∞ in male rats was significantly larger than that in female rats.     

α-Lipoic Acid and Superoxide Dismutase in the Management of Chronic Neck Pain: A Prospective Randomized Study

Background and Objective

Since oxidative stress plays a pathogenetic role in chronic neck pain (CNP), we investigated whether a combination of α-lipoic acid (ALA) and superoxide dismutase (SOD) might improve pain control and the efficacy of physiotherapy (“multimodal therapy”) in patients with CNP.

Setting

This study was conducted in the Rehabilitation Unit of the Department of Surgical and Oncological Sciences at the University Policlinic in Palermo, Italy.

Design and Patients

This was a prospective, randomized, open study in outpatients.

Intervention

Patients randomly received either physiotherapy alone (group 2; n = 45) or a combination of ALA 600 mg and SOD 140 IU daily in addition to physiotherapy (group 1; n = 51), for 60 days. Pain was assessed by a visual analogue scale (VAS) and a modified Neck Pain Questionnaire (mNPQ). Treatment compliance and safety were also evaluated.

Results

Both groups experienced a significant reduction in the VAS and mNPQ scores after 1 month; however, while no further improvement was observed in group 2 at 60 days, group 1 showed a further VAS reduction (p < 0.001). In addition, in the mNPQ at 60 days, more patients in group 1 than in group 2 reported that their neck pain was improved (p < 0.01), and they showed greater compliance with prescribed physiotherapy (p = 0.048). No drug reaction was observed.

Conclusion

Use of ALA/SOD in combination with physiotherapy may be a useful approach to CNP, being antioxidants that act on nerve inflammation and disease progression.

Clinical Rehabilitation Impact

These preliminary observations suggest that some interesting goals (better pain control and physical wellbeing) can be achieved by multimodal therapy in CNP patients.     

Ibuprofen Sodium Is Absorbed Faster than Standard Ibuprofen Tablets: Results of Two Open-Label,Randomized, Crossover Pharmacokinetic Studies

Background

A novel ibuprofen (IBU) formulation, Advil^® Film-Coated Tablets (IBU_Na), was developed.

Objective

Pharmacokinetic comparison of IBU_Na versus other IBU formulations.

Study Design

Two randomized, single-dose, open-label, five-way crossover pharmacokinetic studies.

Setting

Inpatient research clinic.

Subjects

Seventy-one healthy adult volunteers.

Intervention

Study 1: In three periods, fasted subjects received 400-mg IBU dose equivalents as IBU_Na 2 × 256 mg, Advil^® Liqui-Gels^® (IBU_LG) 2 × 200 mg, and Motrin^® IB (IBU_Mot) 2 × 200 mg tablets. In two periods following a high-fat breakfast, subjects received 400-mg IBU dose equivalents as IBU_Na 2 × 256 mg and IBU_LG 2 × 200 mg. Study 2: In five study periods, fasted subjects received 400-mg IBU dose equivalents as IBU_Na 2 × 256 mg, Advil^® FastGel^® (IBU_FG) 2 × 200 mg, Nurofen^® (IBU_Nur) 2 × 200 mg, Advil^® (IBU_Adv) 2 × 200 mg, and Nurofen^® Express containing IBU lysinate (IBU_Lys) 2 × 342 mg.

Main Outcome Measure

Log-transformed area under the plasma concentration versus time curve to last observable concentration (AUC_L) and maximum plasma concentration (C_max) were the primary pharmacokinetic parameters; time to maximum measured plasma concentration (T_max) was analyzed post hoc.

Results

IBU_Na was bioequivalent to IBU_LG (fasted and fed) and IBU_FG and IBU_Lys (fasted) for rate (C_max) and extent (AUC_L) of IBU absorption. After fasting, AUC_L was bioequivalent for IBU_Na and IBU_Mot, IBU_Adv, and IBU_Nur, but C_max occurred significantly earlier with IBU_Na. After fasting, median IBU_NaT_max was comparable to that for IBU_LG, IBU_FG, and IBU_Lys, but was much shorter than that for IBU_Mot, IBU_Nur, and IBU_Adv. Food slowed absorption of IBU_Na and IBU_LG similarly. All treatments were tolerated similarly.

Conclusion

IBU_Na is absorbed faster but to a similar extent as standard IBU formulations.     

Inhaler Competence and Patient Satisfaction with Easyhaler?: Results of Two Real-Life Multicentre Studies in Asthma and COPD

Objective

The aim of this study was to investigate patients’ inhaler competence and satisfaction with the Easyhaler^® dry powder inhaler.

Design

Two open, uncontrolled, non-randomised studies.

Setting

Real life based on patients attending 56 respiratory clinics in Hungary.

Participants

Patients with asthma or chronic obstructive pulmonary disease (COPD) (n = 1016).

Intervention

In a 3-month study, adult patients (age range 18–88 years; n = 797) received twice-daily inhalations of formoterol via Easyhaler^®, and in a consequential study (from one visit to another, with 3–12 months in-between) children and adolescents (age range 4–17 years; n = 219) received salbutamol via Easyhaler^® as needed.

Main Outcome Measures

Control of six Easyhaler^® handling steps and patients’ satisfaction with Easyhaler^® based on questionnaires.

Results

Correct performances (minimum and maximum of the six steps) were noticed after one demonstration in 92–98 % of the adults, 87–99 % of the elderly, 81–96 % of the children and 83–99 % of the adolescents. These figures had markedly increased at the last visit. Repeat instructions were necessary in 26 % of the cases. Investigators found Easyhaler^® easy to teach in 87 % of the patients and difficult in only 0.5 %. Patients found Easyhaler^® easy to learn and use, and the patients’ (and parents’) satisfaction with the inhaler was very high. Lung function values [forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), peak expiratory flow (PEF)] improved statistically significantly during the studies, indicating good inhaler competence and treatment adherence.

Conclusion

Investigators found Easyhaler^® easy to teach and patients found it easy to use, and their satisfaction with the device was high.     

Population pharmacokinetics of oseltamivir in non-pregnant and pregnant women

Aims

Physiological changes in pregnancy are expected to alter the pharmacokinetics of various drugs. The objective of this study was to evaluate systematically the pharmacokinetics of oseltamivir (OS), a drug used in the treatment of influenza during pregnancy.

Methods

A multicentre steady-state pharmacokinetic study of OS was performed in 35 non-pregnant and 29 pregnant women. Plasma concentration–time profiles were analyzed using both non-compartmental and population pharmacokinetic modelling (pop PK) and simulation approaches. A one compartment population pharmacokinetic model with first order absorption and elimination adequately described the pharmacokinetics of OS.

Results

The systemic exposure of oseltamivir carboxylate (OC, active metabolite of OS) was reduced approximately 30 (19–36)% (P < 0.001) in pregnant women. Pregnancy significantly (P < 0.001) influenced the clearance (CL/F) and volume of distribution (V/F) of OC. Both non-compartmental and population pharmacokinetic approaches documented approximately 45 (23–62)% increase in clearance (CL/F) of OC during pregnancy.

Conclusion

Based on the decrease in exposure of the active metabolite, the currently recommended doses of OS may need to be increased modestly in pregnant women in order to achieve comparable exposure with that of non-pregnant women.     

Population pharmacokinetics of ciclosporin in Chinese children with aplastic anemia: effects of weight,renal function and stanozolol administration

Aim:

To develop a population pharmacokinetic model for the immunosuppressant ciclosporin in Chinese children with aplastic anemia and to identify covariates influencing ciclosporin pharmacokinetics.

Methods:

A total of 102 children with either acquired or congenital aplastic anemia aged 8.8±3.6 years (range 0.9–17.6 years) were included. Therapeutic drug monitoring (TDM) data for ciclosporin were collected. The population pharmacokinetic model of ciclosporin was described using the nonlinear mixed-effects modeling (NONMEM) VI software. The final model was validated using bootstrap and normalized prediction distribution errors.

Results:

A one-compartment model with first-order absorption and elimination was developed. The estimated CL/F was 15.1, which was lower than those of children receiving stem cell or kidney transplant reported in the West (16.9–29.3). The weight normalized CL/F was 0.45 (range: 0.27–0.70) Lh⁻¹·kg⁻¹. The covariate analysis identified body weight, serum creatinine and concomitant administration of the anabolic steroid stanozolol as individual factors influencing the CL/F of ciclosporin.

Conclusion:

Our model could be used to optimize the ciclosporin dosing regimen in Chinese children with aplastic anemia.     

Pharmacokinetics of Cefozopran by Single and Multiple Intravenous Infusions in Healthy Chinese Volunteers

Background and Objectives

Cefozopran is a parenteral cephalosporin with a broad spectrum of activity against Gram-positive and Gram-negative bacteria. The objective of this study was to evaluate the pharmacokinetics of cefozopran after single- and multiple-dose intravenous administration in healthy subjects, to provide clinical guidance in its application.

Methods

This was a single-center, open-label, randomized, two-phase study conducted in 12 subjects. In the single-dose phase, subjects were randomly assigned to receive single doses of 0.5, 1.0 and 2.0 g of injected cefozopran hydrochloride in a three-way crossover design with a 5-day washout period between administrations. In the multiple-dose phase, subjects received 2.0 g every 12 h for 4 days. Plasma and urine pharmacokinetic samples were assayed by a validated high-performance liquid chromatography–tandem mass spectrometry method. Pharmacokinetic parameters were calculated and analyzed statistically. Safety assessments were conducted throughout the study.

Results

Twelve healthy volunteers (six males and six females) were enrolled and completed the study. Following a single 1-h intravenous infusion of 0.5, 1.0 or 2.0 g cefozopran, maximum plasma concentration (C_max) and area under the plasma concentration–time curve from time zero to the time of the last measurable concentration (AUC_last) increased in a dose-proportional manner. The mean half-life in plasma (t_½) was in the range of 1.20–2.80 h. Cefozopran was mainly excreted in its unchanged form, with no tendency for accumulation, via the kidney, and varied from 65.99 to 73.33 %. No appreciable accumulation of either drug occurred with multiple intravenous doses of cefozopran, and pharmacokinetic parameters for cefozopran were similar on days 1 and 4. No serious adverse events were reported. Adverse events were generally mild.

Conclusion

Cefozopran was safe and well tolerated in the volunteers and displayed linear increases in the C_max and AUC_last values.     

Release of ATP from rat urinary bladder mucosa: role of acid,vanilloids and stretch

Background and purpose:

ATP, released from urothelial cells, modulates afferent nerve firing from the urinary bladder. Here, we have characterized ATP release from the rat bladder mucosa in response to acid, capsaicin, electrical field stimulation (EFS) and stretch, using agonists and antagonists at transient receptor potential vanilloid receptor 1 (TRPV1) and acid-sensing ion channels (ASICs).

Experimental approach:

Rat mucosal strips (containing urothelium and lamina propria) in Perspex microbaths were superfused with Krebs solution. ATP was measured after exposure of matched strips to acid (pH 6.6–5.0), capsaicin (0.1–10 µM), EFS or stretch (150% of original length).

Key results:

Median basal ATP release was 3.46 nmol·g⁻¹. The mucosal strips responded to stimuli with potency order (median, IQR): acid (pH 5.6–6.0) 286 (103–555) > 10 µM capsaicin 188 (117–431) > 10 Hz EFS 63.0 (13.3–96.4) > stretch 24.4 (6.73–55.1) nmol ATP g⁻¹. ATP release in response to acid was pH dependent (P < 0.05). Responses to capsaicin did not desensitize nor were they concentration dependent. TRPV1 antagonist, capsazepine (10 µM) abolished capsaicin-evoked ATP release, and reduced acid-evoked (pH 6.5) release to 30% (P < 0.001). The ASIC channel antagonists gadolinium (0.1 mM) and amiloride (0.3 µM) reduced (P < 0.05) the acid-evoked (pH 6.5) release to 40 and 6.5% respectively. ASIC (ASIC1, ASIC2a, ASIC2b, ASIC3) and two TRPV1 gene products were detected in mucosal and detrusor extracts.

Conclusions and implications:

Capsaicin (at TRPV1) and acid (at both TRPV1 and ASIC) induce ATP release from the rat bladder mucosa. This ATP appears to be principally of urothelial origin. This study highlights the importance of ATP and acid as signalling molecules in modulating bladder function.     

Saudi young patient understanding of information about side effects: Verbal versus numerical expression

Objective

To determine the effect of providing different formats about side effect information (verbal versus numerical) to acne patients in Saudi Arabia that are newly prescribed Roaccutane.

Design

A prospective study assessing patients’ degree of estimation about side effect information.

Participants

One hundred and forty-one acne patients newly prescribed Roaccutane.

Settings

Four dermatology clinics in Riyadh. Two in tertiary hospitals and the other two in private clinics.

Intervention

Each patient received information about two different side effects for Roaccutane. The side effect provided was supplemented with the probability of occurrence, which was written either in words or in numbers. (Dry eye “very common” or “30%”; Loss of hair “rare” or “0.01%”).

Main outcome measures

Patient’s estimation of side effect occurrence. Other outcomes were the likelihood of experiencing the side effect, the severity of the side effect, their perception of risk of the side effects to their general health, their satisfaction with the information provided and, whether the information provided will influence their decision to take the medicine.

Result

The mean estimate for side effect occurrence for the dry eyes was 46% in the verbal group and 41% in the numerical group (p = 0.5); for loss of hair it was 50% in the verbal group and 39% in the numerical group (p = 0.03). There are no significant differences between verbal and numerical groups regarding the remaining measures.

Conclusion

Patients overestimate the probability of occurrence of side effect. Verbal format of probability of occurrence is associated with higher estimation than the numerical format.     

Pharmacokinetic comparison of inhaled fixed combination vs. the free combination of beclomethasone and formoterol pMDIs in asthmatic children

Aim

The fixed combination of beclomethasone (BDP) and formoterol pressurized metered dose inhaler (pMDI) (Foster®, Chiesi Farmaceutici) is being developed in the lower strength (BDP/formoterol: 50/6 μg) to provide an appropriate dosage for children with asthma. The aim of this work was to investigate the systemic bioavailability of beclomethasone-17-monoproprionate (B17MP, the active metabolite of BDP) and formoterol after single inhalation of Foster® pMDI 50/6 μg vs. the free combination of BDP and formoterol pMDIs in asthmatic children.

Methods

Children aged 5–11 years old inhaled BDP 200 μg and formoterol 24 μg as fixed vs. free combination in an open label, randomized, two way crossover single dose study. Blood was collected pre-dose up to 8 h post-dose for pharmacokinetic evaluation (AUC(0,t), AUC(0,∞), AUC(0,0.5 h, C_max, t_max, t_1/2). Pharmacodynamics included heart rate, plasma potassium, urinary glucose and cortisol excretion. Peak expiratory flow and adverse events were monitored.

Results

Twenty subjects were evaluable. The systemic exposure of B17MP and formoterol administered as fixed combination did not exceed the free combination: B17MP AUC(0,t) (pg ml⁻¹ h) ratio test : reference (90% CI), 0.81 (0.697, 0.948) and formoterol AUC(0,t) (pg ml⁻¹ h) ratio test : reference 0.97 (0.85, 1.10). All pharmacokinetic and pharmacodynamic end points showed non-superiority in favour of the test drug. One adverse event (vertigo) occurred but was not considered treatment-related.

Conclusion

BDP and formoterol pharmacokinetic and pharmacodynamic effects are non-superior after administration of the two actives as fixed vs. the free combination in 5–11-year-old asthmatic children.