The oral route of drug delivery is the most widespread and preferred route of administration, but it has several limitations, including variable pharmacokinetics (PK), reduced dissolution and absorption, and gastrointestinal irritation. Further, many compounds have low aqueous solubility, which also limits intestinal absorption. For this narrative review, we conducted a literature search of PubMed until August 2022, focusing on emulsions, microemulsions, nanoemulsions, and self-emulsifying drug delivery systems. The self-microemulsifying drug delivery system (SMEDDS) overcomes these limitations of hydrophobic compounds to enhance their bioavailability. A SMEDDS formulation is a clear, thermodynamically stable, oil-in-water emulsion of lipid, solubilized drug, and two surfactants, which spontaneously forms droplets < 100 nm in diameter. These components help deliver presolubilized drugs to the gastrointestinal tract, while protecting them from degradation in gastric acid or first-pass hepatic metabolism. SMEDDS formulations have improved oral drug delivery in the treatment of cancer (paclitaxel), viral infections (ritonavir), and migraine headache (ibuprofen and celecoxib oral solution). The American Headache Society recently updated their consensus statement for the acute treatment of migraine and included a selective cyclo-oxygenase-2 selective inhibitor formulated in SMEDDS, celecoxib oral solution. This SMEDDS formulation showed pronounced improvement in bioavailability compared with celecoxib capsules, allowing for a low dose of celecoxib in the oral solution to provide safe and effective acute migraine treatment. Here, we will focus on SMEDDS formulations, what differentiates them from other analogous emulsions as vehicles for poorly soluble drugs, and their clinical application in the acute treatment of migraine. Oral drugs reformulated in SMEDDS have shown accelerated times to peak plasma drug concentrations and increased maximum plasma concentrations, compared with capsules, tablets, or suspensions. SMEDDS technology increases both drug absorption and bioavailability of lipophilic drugs, compared with other formulations. Clinically, this allows the use of lower doses with improved PK profiles without compromising efficacy, as shown with celecoxib oral solution for the acute treatment of migraine.
Sarah M. Bobker declares no conflict of interest. Jenn Vallimont receives payment from the American Headache Society for her role as Managing Editor of Headache.
Purpose of Review Post-traumatic headache (PTH) consequent to mild traumatic brain injury (mTBI) is a complex, multidimensional, chronic neurological disorder. The purpose of this review is to evaluate the current neuroimaging studies on mTBI and PTH with a specific focus on brain networks and connectivity patterns. Recent Findings We present findings on PTH incidence and prevalence, as well as the latest neuroimaging research findings on mTBI and PTH. Additionally, we propose a new strategy in studying PTH following mTBI. The diversity and heterogeneity of pathophysiological mechanisms underlying mild traumatic brain injury pose unique challenges on how we interpret neuroimaging findings in PTH. Evaluating alterations in the intrinsic brain network connectivity patterns using novel imaging and analytical techniques may provide additional insights into PTH disease state and therefore inform effective treatment strategies.
Background The FOCUS study evaluated the efficacy of migraine preventive medications across different countries within the same patient population, particularly for patients with difficult-to-treat migraine. These prespecified subgroup analyses evaluated efficacy by country in the FOCUS study of fremanezumab in adults with episodic migraine or chronic migraine and documented inadequate response to 2 to 4 migraine preventive medication classes. Methods Overall, 838 participants were enrolled in the FOCUS study, a randomized, double-blind, placebo-controlled, parallel-group, phase 3b study performed at 104 sites. For 12 weeks of double-blind treatment, patients were randomized (1:1:1) to quarterly fremanezumab, monthly fremanezumab, or matched placebo. The primary efficacy endpoint was the mean change from baseline in monthly average migraine days over 12 weeks of double-blind treatment, evaluated by country in these subgroup analyses. Results Of 14 countries contributing data, the Czech Republic ( n = 188/838; 22%), the United States ( n = 120/838; 14%), and Finland ( n = 85/838; 10%) enrolled the most patients. Changes from baseline in monthly average migraine days over 12 weeks were significantly greater with fremanezumab versus placebo for patients in these countries: Czech Republic (least-squares mean difference versus placebo [95% confidence interval]: quarterly fremanezumab, − 1.9 [− 3.25, − 0.47]; P = 0.009; monthly fremanezumab, − 3.0 [− 4.39, − 1.59]; P < 0.001), the United States (quarterly fremanezumab, − 3.7 [− 5.77, − 1.58]; P < 0.001; monthly fremanezumab, − 4.2 [− 6.23, − 2.13]; P < 0.001), and Finland (quarterly fremanezumab, − 3.0 [− 5.32, − 0.63]; P = 0.014; monthly fremanezumab, − 3.9 [− 6.27, − 1.44]; P = 0.002). Results were comparable for the remaining 9 countries, with the least-squares mean difference versus placebo ranging from – 5.6 to – 2.4 with quarterly fremanezumab and from − 5.3 to − 1.5 with monthly fremanezumab. Incidences of serious adverse events and adverse events leading to discontinuation were low and comparable across countries and treatment groups. Conclusions Monthly and quarterly fremanezumab significantly reduced the monthly average number of migraine days versus placebo regardless of country and continent (North America versus Europe) in migraine patients with documented inadequate response to 2 to 4 migraine preventive medication classes. Trial registration ClinicalTrials.gov Identifier: NCT03308968 .
Objective To evaluate the association between the degree of response to placebo in migraine studies and the observed difference between drug and placebo across studies of preventative treatments for migraine. Methods A systematic review was performed using MEDLINE and the Cochrane Central Register of Controlled Clinical Trials from January 1988 to June 2019. Randomized, double-blind, parallel-group, placebo-controlled trials on oral or injection preventative treatments for migraine were included. Single- and multi-variable linear regression analyses were performed on the placebo-subtracted response rate (i.e. placebo responders subtracted from active responders), and the proportion of placebo responders. Fisher's exact tests were performed on the level of placebo response and the success in meeting the study's primary endpoint. Results After adjusting for route of administration and number of randomized subjects, there was a statistically significant association between the proportion of patients who were placebo responders and the placebo-subtracted response rate (b = -0.27,p = 0.02). There was a statistically significant difference in trial success rate (60%) between studies with <= 20% placebo responders and studies with > 30% placebo responders (p = 0.03). Conclusion Considering the detrimental impact that high placebo response can have on clinical trials, it is imperative to find effective solutions to decrease the placebo response and increase assay sensitivity.
