Beate Rohde

Amyloid Imaging with 18 F-Florbetaben in Alzheimer Disease and Other Dementias

Amyloid imaging with 18F-labeled radiotracers will allow widespread use, facilitating research, diagnosis, and therapeutic development for Alzheimer disease. The purpose of the study program was to compare cortical amyloid deposition using 18F-florbetaben and PET in controls and subjects with mild cognitive impairment (MCI), frontotemporal lobar degeneration (FTLD), dementia with Lewy bodies (DLB), vascular dementia (VaD), Parkinson disease (PD), and Alzheimer disease (AD). Methods: One hundred nine subjects in 3 clinical studies at Austin Health were reviewed: 32 controls, 20 subjects with MCI, and 30 patients with AD, 11 with FTLD, 7 with DLB, 5 with PD, and 4 with VaD underwent PET after intravenous injection of 300 MBq of 18F-florbetaben. Standardized uptake value ratios (SUVR) using the cerebellar cortex as a reference region were calculated between 90 and 110 min after injection. Results: When compared with the other groups, AD patients demonstrated significantly higher SUVRs (P < 0.0001) in neocortical areas. Most AD patients (96%) and 60% of MCI subjects showed diffuse cortical 18F-florbetaben retention. In contrast, only 9% of FTLD, 25% of VaD, 29% of DLB, and no PD patients and 16% of controls showed cortical binding. Although there was a correlation between Mini Mental State Examination and β-amyloid burden in the MCI group, no correlation was observed in controls, FTLD or AD. Conclusion: 18F-florbetaben had high sensitivity for AD, clearly distinguished patients with FTLD from AD, and provided results comparable to those reported with 11C-Pittsburgh Compound B in a variety of neurodegenerative diseases.

The safety and pharmacokinetics of rapid iloprost aerosol delivery via the BREELIB nebulizer in pulmonary arterial hypertension

The BREELIB nebulizer was developed for iloprost to reduce inhalation times for patients with pulmonary arterial hypertension (PAH). This multicenter, randomized, unblinded, four-part study compared inhalation time, pharmacokinetics, and acute tolerability of iloprost 5 µg at mouthpiece delivered via BREELIB versus the standard I-Neb nebulizer in 27 patients with PAH. The primary safety outcome was the proportion of patients with a maximum increase in heart rate (HR) ≥ 25% and/or a maximum decrease in systolic blood pressure ≥ 20% within 30 min after inhalation. Other safety outcomes included systolic, diastolic, and mean blood pressure, HR, oxygen saturation, and adverse events (AEs). Median inhalation times were considerably shorter with BREELIB versus I-Neb (2.6 versus 10.9 min; n = 24). Maximum iloprost plasma concentration and systemic exposure (area under the plasma concentration–time curve) were 77% and 42% higher, respectively, with BREELIB versus I-Neb. Five patients experienced a maximum systolic blood pressure decrease ≥ 20%, four with BREELIB (one mildly and transiently symptomatic), and one with I-Neb; none required medical intervention. AEs reported during the study were consistent with the known safety profile of iloprost. The BREELIB nebulizer offers reduced inhalation time, good tolerability, and may improve iloprost aerosol therapy convenience and thus compliance for patients with PAH.

Prediction of In Vivo Drug Interaction from In Vitro Systems Exemplified by Interaction Between Verapamil and Cimetidine Using Human Liver Microsomes and Primary Hepatocytes

Emphasis on drug safety is increasing as newly developed drugs become more potent. Interest in the prediction and description of drug interactions is growing accordingly. The study of potential interactions at a very early stage of drug development requires suitable in vitro models that describe drug interactions both qualitatively and quantitatively. The purpose of the work described here was to help assess the predictive value of in vitro drug interaction tests with liver microsomes and hepatocytes by means of the interaction between verapamil and cimetidine. The in vitro inhibition of verapamil metabolism by cimetidine observed during the studies was quantitatively similar to the results reported in published clinical studies after intravenous application. Studies using liver microsome fractions showed that the intrinsic clearances for the formation of various metabolites could be used to predict drug interactions. In addition, work with hepatocyte cultures revealed that an in vitro system covering both phase I and phase II reactions should be included in such studies to permit quantitative prediction of the various metabolic pathways. Both human hepatocyte cultures and human microsomes offer certain advantages for predicting the degree of drug metabolism and interactions in humans at the biotransformation level. Therefore, it seems likely that the simultaneous application of both systems will yield conclusions that most closely approximate the situation in humans.

Effect of the Novel Selective Progesterone Receptor Modulator Vilaprisan on Ovarian Activity in Healthy Women

This randomized, double‐blind, parallel‐group study in healthy young women investigated the effect of treatment with vilaprisan (0.5, 1, 2, or 4 mg/day for 12 weeks) on ovarian function by assessing the Hoogland score, which is based on the size of follicle‐like structures as determined by transvaginal ultrasound and on estradiol and progesterone serum concentrations. Ovulation inhibition (ie, Hoogland score <6 in treatment weeks 1‐4 and 8‐12) was observed in >80% of the subjects receiving vilaprisan ≥1 mg/day. The effect was dose dependent. With a Bayesian approach, the percentage of subjects with ovulation inhibition was estimated to increase from 37% in subjects receiving 0.5 mg/day vilaprisan to 76%, 86%, and 88% in subjects receiving 1, 2, and 4 mg/day, respectively. Follicle growth was not suppressed during treatment. The majority of subjects receiving ≥1 mg/day had a Hoogland score of 4 (active follicle‐like structures, ie, follicle diameter >13 mm, estradiol >27.2 pg/mL, no progesterone increase) both at beginning and end of treatment. Mean average estradiol as well as mean maximum progesterone concentrations were noticeably decreased during treatment with vilaprisan ≥1 mg/day compared to pretreatment, but estradiol concentrations remained >80 pg/mL. Both hormones returned to pretreatment levels after the end of treatment, indicating a rapid resumption of normal ovarian activity. Amenorrhea occurred in the majority of subjects during treatment at dosages ≥1 mg/day. The adverse events observed in this study confirm the known safety profile of vilaprisan. All in all, the results of this study support the development of vilaprisan for the long‐term treatment of uterine fibroids.

In Vivo Formation of Ethinylestradiol After Intramuscular Administration of Norethisterone Enantate

It is known that a small fraction of orally administered norethisterone is metabolically converted to ethinylestradiol. This exploratory, open‐label, nonrandomized study was conducted to investigate the systemic exposure to ethinylestradiol after intramuscular administration of norethisterone enantate in comparison with the exposure to ethinylestradiol after administration of a standard combined oral contraceptive. Sixteen healthy premenopausal women received an oral contraceptive (ethinylestradiol 30 μg/levonorgestrel 150 μg) once daily for 21 days and—after a 1‐week washout period—a single intramuscular dose of 200 mg norethisterone enantate. Blood samples to determine ethinylestradiol in serum were taken over 24 hours after the last dose of ethinylestradiol/levonorgestrel and over 8 weeks after administration of norethisterone enantate. Oral equivalent doses of ethinylestradiol were estimated based on area under the concentration–time curves. The ethinylestradiol serum concentrations observed after administration of norethisterone enantate were relatively low: The mean maximum concentration was only 32% of the maximum observed after ethinylestradiol/levonorgestrel (90% confidence interval, 22.5%–44.7%). The maximum oral equivalent dose of ethinylestradiol was markedly lower than 30 μg ethinylestradiol per day (20.3 μg/day; 90% confidence interval, 14.8–28.0 μg/day). The same applied to the average oral equivalent dose of ethinylestradiol for the 8‐week postdose interval (4.41 μg/day; 90% confidence interval, 3.57–5.46 μg/day). To conclude, the study results indicate that metabolic conversion of norethisterone to ethinylestradiol also occurs after intramuscular administration of 200 mg norethisterone enantate, but is associated with a lower exposure to ethinylestradiol than the use of a combined oral contraceptive containing 30 μg ethinylestradiol (plus 150 μg levonorgestrel).

Monoclonal Antibody Against Prolactin Receptor: A Randomized Placebo-Controlled Study Evaluating Safety, Tolerability, and Pharmacokinetics of Repeated Subcutaneous Administrations in Postmenopausal Women

BAY 1158061 is a potent monoclonal prolactin (PRL) receptor antibody, blocking PRL receptor (PRLR)-mediated signaling in a noncompetitive manner, which was tested in a randomized, placebo-controlled multiple dose study in postmenopausal women. The objective was to investigate safety, tolerability, pharmacokinetic characteristics, and effects of BAY 1158061 on serum PRL level. The study consisted of 4 parallel groups receiving up to 3 subcutaneous (sc) administrations of BAY 1158061 or placebo in 2 different dosing regimens. Twenty-nine healthy postmenopausal women were randomized and treated with BAY 1158061 or placebo: 30 mg at 14-day interval (7 participants), 60 mg at 28-day interval (8 participants), 90 mg at 14-day interval (7 participants), and placebo (7 participants). To keep the blinding, all randomized participants received sc injections biweekly (14-day interval) on 3 occasions in the lower abdomen. The PRLR antibody showed a favorable safety and tolerability profile in postmenopausal women with no distinct differences in occurrence of adverse events in BAY 1158061 or placebo-treated participants. BAY 1158061 displayed low immunogenicity with low titers of antidrug antibodies and absence of neutralizing antidrug antibodies. Pharmacokinetics were characterized by slow absorption after sc administration with median peak plasma concentrations 7 to 11 days after first dose and about 2-fold accumulation after repeated dosing every 2 weeks. The apparent mean elimination half-life was 9 to 16 days. The PRL concentration–time profiles over 24 hours showed no differences between verum- and placebo-treated participants. Based on the data obtained, BAY 1158061 is considered a good candidate for further development in endometriosis or other PRL-mediated disease conditions.

Topical administration of regorafenib eye drops: phase I dose‐escalation study in healthy volunteers

Aim Regorafenib is a multikinase inhibitor under investigation for use in neovascular age‐related macular degeneration. In this phase I study, regorafenib eye drops were administered to healthy volunteers to provide information on safety, tolerability and systemic exposure. Methods This was a single‐centre, randomized, double‐masked, parallel‐group, dose‐escalation, placebo‐controlled study. Subjects received regorafenib eye drops (30 mg ml−1, 25 μl) as a 0.75 mg single dose (Cohort 1), 0.75 mg twice daily (bid) or thrice daily (tid) over 14 days (Cohorts 2 and 3, respectively), 1.5 mg tid unilaterally for 3 days, then bilaterally for up to 14 days (Cohort 4), or placebo. Plasma samples were taken to estimate systemic exposure. Safety and functional assessments were performed throughout the study. Results Thirty‐six subjects received regorafenib and 12 received placebo. Regorafenib was safe and well tolerated over the dose range. No pathological changes occurred in the anterior, vitreous or posterior eye compartments. Mild eyelid redness, oedema and conjunctival hyperaemia were observed across all regorafenib cohorts; these were comparable with the effects seen with placebo. Predominant symptoms were blurred vision in the active and placebo groups. Systemic safety evaluations showed no clinically relevant findings. Absolute systemic exposure after multiple administrations of regorafenib eye drops at a dose of 0.75 mg was 600–700‐fold lower than after multiple oral administration of 160 mg day−1, the dose approved in cancer indications. Conclusion These results indicate a favourable safety and tolerability profile of regorafenib eye drops up to 30 mg ml−1 tid for use in clinical studies.