Pharmacokinetics of Roflumilast Cream in Chronic Plaque Psoriasis: Data from Phase I to Phase III Studies

BACKGROUND

Most patients with chronic plaque psoriasis receive topical treatment; however, available options lack a balance of efficacy with long-term safety and tolerability. Roflumilast cream 0.3% is a highly potent phosphodiesterase 4 (PDE4) inhibitor approved by the US FDA for treatment of psoriasis.

OBJECTIVE

The aim of this study was to define the pharmacokinetic (PK) profile of roflumilast delivered topically from a phase I maximal usage study and data from phase II and phase III studies.

METHODS

PK data for roflumilast and the active metabolite, roflumilast N-oxide, were determined from a phase I PK and safety maximal usage study of roflumilast cream 0.3% applied once daily for 14 days in patients with plaque psoriasis affecting body surface area (BSA) ≥20% (N = 26). Serial plasma samples were obtained on Days 1 and 15 to determine maximum plasma concentration (C_max) and area under the concentration-time curve (AUC). Plasma concentrations were also assessed at Weeks 3, 4, and 5 for terminal half-life (t_½). Concentrations of roflumilast and roflumilast N-oxide in skin were assessed at Day 28 for 14 patients with psoriasis in a phase I/IIa study of once-daily roflumilast cream 0.5% and 0.15% for 28 days. Systemic exposure (C_trough and AUC) of roflumilast and roflumilast N-oxide in two phase III trials (DERMIS-1, n = 245; DERMIS-2, n = 250) of roflumilast cream 0.3% for 8 weeks was assessed at Weeks 4 and 8.

RESULTS

Bioavailability of roflumilast cream 0.3% after topical administration was 1.5%. Unlike after oral dosing, the plasma concentration-time curve was flat, with a peak-to-trough ratio of 1.2. Roflumilast N-oxide concentrations were eightfold higher than roflumilast concentrations. The t_½ in adult patients was 4.0 days for roflumilast and 4.6 days for roflumilast N-oxide following the last dose administered. Steady state was reached by Day 15. Concentrations of roflumilast in skin were, on average, 126- and 61.8-fold higher than corresponding mean plasma C_trough following administration of roflumilast cream 0.15% and 0.5% daily for 28 days. Roflumilast N-oxide was quantifiable in only one skin sample (N = 27). Following 8 weeks of treatment in DERMIS-1, mean plasma C_trough of roflumilast was 1.78 ng/mL, and 9.86 ng/mL for roflumilast N-oxide. In DERMIS-2, mean plasma C_trough was 1.72 ng/mL and 10.2 ng/mL, respectively. In the maximal usage study (mean BSA: 27.5%), eight patients (30.8%) experienced adverse events (AEs) and all were mild or moderate, with no reports of diarrhea, headache, insomnia, or application-site pain; no patients discontinued treatment due to an AE.

CONCLUSION

Topical administration of roflumilast cream 0.3% results in concentrations in skin 126- and 61.8-fold higher relative to plasma, which are much higher than expected to be achievable with oral dosing. PDE4 inhibition in the skin is likely due to roflumilast as compared with its active metabolite, as there is no significant conversion to roflumilast N-oxide in the skin. Consistent with reservoir formation and retention of drug in the stratum corneum, roflumilast is slowly released from the skin (t_½ 4 days) and peak-to-trough ratio is 1.2.

CLINICALTRIALS

GOV IDENTIFIERS

NCT04279119, NCT03392168, NCT04211363, NCT04211389.

Roflumilast Cream Improves Signs and Symptoms of Plaque Psoriasis: Results from a Phase 1/2a Randomized, Controlled Study

Background: Roflumilast cream (ARQ-151) is a highly potent, selective phosphodiesterase-4 inhibitor in development for once-daily topical treatment of chronic plaque psoriasis. Objectives: To assess the safety and efficacy of once-daily roflumilast cream 0.5% and 0.15% in patients with chronic plaque psoriasis. Methods: This phase 1/2a study enrolled a single-dose, open-label cohort (Cohort 1: 0.5% cream applied to 25 cm² psoriatic plaques), and a 28-day, double-blinded cohort (Cohort 2: 1:1:1 randomization to roflumilast cream 0.5%, 0.15%, or vehicle). Patients had chronic plaque psoriasis of >6 months' duration with ≤5% body surface area involvement. Outcomes included safety (adverse events) and efficacy (percentage change in the Target Plaque Severity Score [TPSS] × Target Plaque Area [TPA]) at week 4. Results: For Cohorts 1 (n=8) and 2 (n=89), adverse events (all mild/moderate; none severe or serious) were similar between active arms and vehicle. Treatment-related events were confined to the application site, without differences between drug and vehicle. No patient discontinued treatment due to adverse events. The primary efficacy endpoint was met for both roflumilast cream doses: TPSS×TPA improvement at week 4 was statistically significant for roflumilast 0.5% (P=0.0007) and 0.15% (P=0.0011) versus vehicle; significance was reached as early as 2 weeks. For both roflumilast cream doses, 66%-67% improvement from baseline was observed at week 4, without reaching a plateau, versus 38% improvement for vehicle. Conclusion: Roflumilast cream was safe and highly effective at doses of 0.5% and 0.15% and represents a potential novel once-daily topical therapy for the treatment of chronic plaque psoriasis. ClinicalTrials.gov NCT03392168. J Drugs Dermatol. 2020;19(8): doi:10.36849/JDD.2020.5370.

Trial of Roflumilast Cream for Chronic Plaque Psoriasis

BACKGROUND

Systemic oral phosphodiesterase type 4 (PDE-4) inhibitors have been effective in the treatment of psoriasis. Roflumilast cream contains a PDE-4 inhibitor that is being investigated for the topical treatment of psoriasis.

METHODS

In this phase 2b, double-blind trial, we randomly assigned adults with plaque psoriasis in a 1:1:1 ratio to use roflumilast 0.3% cream, roflumilast 0.15% cream, or vehicle (placebo) cream once daily for 12 weeks. The primary efficacy outcome was the investigator's global assessment (IGA) of a status of clear or almost clear at week 6 (assessed on a 5-point scale of plaque thickening, scaling, and erythema; a score of 0 indicates clear, 1 almost clear, and 4 severe). Secondary outcomes included an IGA score indicating clear or almost clear plus a 2-grade improvement in the IGA score for the intertriginous area and the change in the Psoriasis Area and Severity Index (PASI) score (range, 0 to 72, with higher scores indicating worse disease). Safety was also assessed.

RESULTS

Among 331 patients who underwent randomization, 109 were assigned to roflumilast 0.3% cream, 113 to roflumilast 0.15% cream, and 109 to vehicle cream. An IGA score indicating clear or almost clear at week 6 was observed in 28% of the patients in the roflumilast 0.3% group, in 23% in the roflumilast 0.15% group, and in 8% in the vehicle group (P<0.001 and P = 0.004 vs. vehicle for roflumilast 0.3% and 0.15%, respectively). Among the approximately 15% of patients overall who had baseline intertriginous psoriasis of at least mild severity, an IGA score at week 6 indicating clear or almost clear plus a 2-grade improvement in the intertriginous-area IGA score occurred in 73% of the patients in the roflumilast 0.3% group, 44% of those in the roflumilast 0.15% group, and 29% of those in the vehicle group. The mean baseline PASI scores were 7.7 in the roflumilast 0.3% group, 8.0 in the roflumilast 0.15% group, and 7.6 in the vehicle group; the mean change from baseline at week 6 was -50.0%, -49.0%, and -17.8%, respectively. Application-site reactions occurred with similar frequency in the roflumilast groups and the vehicle group.

CONCLUSIONS

Roflumilast cream administered once daily to affected areas of psoriasis was superior to vehicle cream in leading to a state of clear or almost clear at 6 weeks. Longer and larger trials are needed to determine the durability and safety of roflumilast in psoriasis. (Funded by Arcutis Biotherapeutics; ARQ-151 201 ClinicalTrials.gov number, NCT03638258.).

Skin Penetration and Permeation Properties of Transcutol®-Neat or Diluted Mixtures

A heightened interest in (trans)dermal delivery is in part driven by the need to improve the existing skin therapies and also the demand for alternative routes of administration, notably for pharmaceutical actives with undesirable oral absorption characteristics. The premise of delivering difficult actives to the skin or via the skin however is weighed down by the barrier function properties of the stratum corneum. Short of disrupting the skin by physical means, scientists have resorted to formulation with excipients known to enhance the skin penetration and permeation of drugs. A vehicle that has emerged over the years as a safe solubilizer and enhancer for a broad range of drug actives is the highly purified NF/EP grade of diethylene glycol monoethyl ether (DEGEE) commercially known as Transcutol®. Whereas numerous studies affirm its enhancing effect on drug solubilization, percutaneous absorption rate, and/or drug retention in the skin, there are few publications that unite the body of the published literature in describing the precise role and mechanisms of action for Transcutol®. In view of the current mechanistic understanding of skin barrier properties, this paper takes on a retrospective review of the published works and critically evaluates the data for potential misses due to experimental variables such as formulation design, skin model, skin hydration levels, and drug properties. The goal of this review is to mitigate the incongruence of the published works and to construct a unified, comprehensive understanding of how Transcutol® influences skin penetration and permeation. Graphical Abstract Transcutol has affinity for the hydrophilic head groups of the stratum corneum structures.

Gel formulation containing mixed surfactant and lipids associating with carboplatin

The interaction of amphiphilic molecules such as lipids and surfactants with the hydrophilic drug carboplatin was investigated to identify suitable self-assembling components for a potential gel-based delivery formulation. (1) H-NMR Studies in sodium bis(2-ethylhexyl) sulfosuccinate (aerosol-OT, AOT)-based reverse micelles show that carboplatin associates and at least partially penetrates the surfactant interface. Langmuir monolayers formed by dipalmitoyl(phosphatidyl)choline are penetrated by carboplatin. Carboplatin was found to also penetrate the more rigid monolayers containing cholesterol. A combined mixed surfactant gel formulation containing carboplatin and cholesterol for lymphatic tissue targeting was investigated for the intracavitary treatment of cancer. This formulation consists of a blend of the surfactants lecithin and AOT (1 : 3 ratio), an oil phase of isopropyl myristate, and an aqueous component. The phases of the system were defined within a pseudo-ternary phase diagram. At low oil content, this formulation produces a gel-like system over a wide range of H(2) O content. The carboplatin release from the formulation displays a prolonged discharge with a rate three to five times slower than that of the control. Rheological properties of the formulation exhibit pseudoplastic behavior. Microemulsion and Langmuir monolayer studies support the interactions between carboplatin and amphiphilic components used in this formulation. To target delivery of carboplatin, two formulations containing cholesterol were characterized. These two formulations with cholesterol showed that, although cholesterol does little to alter the phases in the pseudo-ternary system or to increase the initial release of the drug, it contributes significantly to the structure of the formulation under physiological temperature, as well as increases the rate of steady-state discharge of carboplatin.

Microemulsions as topical drug delivery vehicles: in-vitro transdermal studies of a model hydrophilic drug

Microemulsions with a 58:42 weight ratio of dioctyl sodium sulphosuccinate: octanol and containing 15, 35, and 68% water have been tested for their ability to transport glucose across human cadaver skin. A flow-through multisample skin diffusion cell showed that both the 35 and 68% water microemulsions caused enhanced (approximately 30-fold) transport of glucose. No transport was discernible for the 15% water microemulsion. Differences in percutaneous glucose transport were shown to parallel differences in the diffusion of water within the microemulsion vehicles before application to the skin.

Cremophor-free intravenous microemulsions for paclitaxel I: formulation, cytotoxicity and hemolysis

Two cremophor-free microemulsions, lecithin:butanol:myvacet oil:water (LBMW) and capmul:myvacet oil:water (CMW) for paclitaxel (PAC) were developed for intravenous (i.v.) administration. Six surfactants and four oils were screened with various combinations for maximal water incorporation and PAC solubility. Microemulsion regions were subsequently determined in ternary phase diagrams. Cytotoxicity in an MDA-M231 human breast cancer cell line and hemolytic potential were assessed in these systems compared to Taxol (cremophor EL:ethanol, 1:1, 6 mgPAC/ml). The maximal water incorporation into the lecithin:butanol surfactant blend was greater than that incorporated into capmul when combined with the oils screened. PAC solubility in myvacet oil was increased 1389-fold over its aqueous solubility. LBMW had a larger microemulsion region (46.5% of total ternary phase diagram) than that seen with CMW (18.6%). The droplet size of the dispersed phase was 111.5 (4.18)nm for LBMW and 110.3 (8.09)nm for CMW. Cytotoxicity of PAC was in decreasing order of: Taxol>LBMW>CMW. The IC50 values for LBMW and CMW ranged from 4.5 to 5.7 and >10 microM, respectively, as compared to that of Taxol (1.3 to 1.8 microM). Eighty-three percent, 68%, and 63% of red blood cells remain unlysed at a formulation volume to blood ratio of 0.035 in LBMW, CMW and Taxol. Promising microemulsions, LBMW and CMW were developed that can incorporate approximately 12 mg/g of PAC, substantially higher than its aqueous solubility (10.8 microg/ml) and that in the Taxol vehicle (6 mg/ml). PAC retained its cytotoxicity in the LBMW and CMW and was less likely to cause hemolysis compared to Taxol. This higher drug loading results in a smaller vehicle volume in required doses of these formulations and potentially less vehicle-related side effects are anticipated.

Pharmacokinetic profiles in rats after intravenous, oral, or dermal administration of dapsone

Dapsone is a potent anti-inflammatory and antibacterial agent that has been used extensively in the oral treatment of leprosy and dermatitis herpetiformis. This study compared the pharmacokinetic profile of dapsone in rats given a single oral or i.v. 12 mg/kg dose (n = 8/group) or a single dermal application of 12 or 60 mg/kg (n = 12/group) in an aqueous gel application medium containing 10 or 25% diethylene glycol monoethyl ether (DGME). Blood samples (200 microl) were collected via tail vein from each rat and pooled at intervals up to the 24-h period. A terminal blood sample was collected by cardiac puncture from each animal. Plasma concentrations of dapsone were determined by liquid chromatography atmospheric pressure ionization tandem mass spectroscopy. There was no treatment-related overt toxicity observed in any of the animals. Peak levels were reached 1 h after oral dosing (4890 ng/ml), and 6 to 8 h after dermal application, with Cmax values of 1.62, 5.56, and 12.8 ng/ml, for 12 mg/kg at 10 or 25% DGME, and for 60 mg/kg at 25% DGME, respectively. Bioavailability was calculated at 78% after oral dosing and <1% after dermal application. Apparent elimination half-lives (t(1/2))s were similar after i.v. and oral dosing. Both the calculated area under the plasma concentration versus time curve up to 24 h and Cmax values were 3- to 4-fold higher in the dermal application group administered 12 mg/kg dapsone in 25 versus 10% DGME gel, whereas the calculated area under the plasma concentration versus time curve up to 24 h and Cmax values for the 60 mg/kg group were only 3.3- and 2.3-fold greater than those obtained after application of 12 mg/kg in 25% DGME. These results show that both systemic exposure and peak plasma concentrations of dapsone are minimized by dermal versus oral administration of the compound.

A double-blind, placebo-controlled study of topical tetracaine in the treatment of herpes labialis

BACKGROUND

Before the September 1996 approval of 1% penciclovir cream for the treatment of herpes labialis, no other prescription topical therapy was approved for the treatment of this recurrent viral disease affecting approximately 20% of the adult population of the United States. Local anesthetics, such as tetracaine, have been used in over-the-counter topical products, but are only labeled for the relief of pain and itching associated with cold sores and fever blisters.

OBJECTIVE

The purpose of this study was to determine whether a topical preparation of a tetracaine cream is safe and effective in the treatment of recurrent herpes labialis in immunocompetent patients.

METHODS

A double-blind, placebo-controlled study was conducted to assess the relative effectiveness and safety of 1.8% tetracaine equivalent in a cream base versus placebo in the treatment of herpes labialis in immunocompetent adults. In this study, patients applied medication up to 6 times daily until the lesions healed (scab loss), but for no more than 12 days. The patients were monitored on the day of enrollment, once during the course of treatment, and at a final visit after the lesions had healed. Patients assessed themselves the day of scab formation and the day the scab fell off. They also graded, on a daily basis, their perception of relief from itching and pain and the overall benefit.

RESULTS

The results from 72 patients (35 = placebo; 37 = active) showed that scab formation occurred in a mean of 2.4 +/- 0.27 days for the placebo group and 2. 3 +/- 0.26 days for the active group. Healing time (scab loss) occurred in a mean 7.2 +/- 0.36 days for the placebo group and in 5. 1 +/- 0.35 days in the active group. The difference observed for healing time between the placebo and the active tetracaine cream was statistically significant (P =.0002). This represents an approximately 30% reduction in the healing time for the active group compared with the placebo group. In addition, the study patients ranked the benefit of their treatment on a daily basis and graded the overall benefit of the therapy at their final visit. The ranking was on a 1 to 10 index scale (1 = no benefit at all; 10 = very effective treatment). At the final visit there was a statistically significant difference in the benefit index for active preparation versus placebo for this subjective evaluation (placebo index, 5.9 +/- 0.6; active index, 7.3 +/- 0.48 [P =.0359]). The subjects also evaluated relief from itching and pain on a daily basis. Relief from itching was significantly greater in the active group than in the placebo group on days 2 and 3 after initiation of the treatment. Pain was not found to be severe in either the placebo or active treatment groups. At day 2 of treatment and beyond, pain scores never were greater than 3.2 +/- 0.28 for active on a scale in which 1.0 represented "no pain at all" and 10 represented "most severe pain imaginable." Although mean values for pain were always less for the active therapy, lesional pain scores never reached statistically significant lower values for active compared with placebo.

CONCLUSION

Our findings indicate that a 1.8% topical tetracaine cream, when applied frequently, significantly reduces the healing time of recurrent herpes labialis lesions. Additionally, it is perceived by the study subjects to reduce itching of the lesions and to have a beneficial overall effect.

Microemulsions as topical drug delivery vehicles: in-vitro transdermal studies of a model hydrophilic drug

Microemulsions with a 58:42 weight ratio of dioctyl sodium sulphosuccinate: octanol and containing 15, 35, and 68% water have been tested for their ability to transport glucose across human cadaver skin. A flow-through multisample skin diffusion cell showed that both the 35 and 68% water microemulsions caused enhanced (approximately 30-fold) transport of glucose. No transport was discernible for the 15% water microemulsion. Differences in percutaneous glucose transport were shown to parallel differences in the diffusion of water within the microemulsion vehicles before application to the skin.

Determination of the effect of tridiphane on the pharmacokinetics of [14C]-atrazine following oral administration to male Fischer 344 rats

The absorption, distribution, metabolism and excretion of [14C]-atrazine was studied in male Fischer 344 rats administered a 30 mg [14C]-atrazine/kg of body weight oral dose with or without pretreatment with a non-radiolabeled oral dose of 60 mg tridiphane/kg of body weight. The objective of this study was to determine whether tridiphane had any meaningful effect on the pharmacokinetics and/or metabolism of atrazine in the rat. The 14C plasma time-course exhibited a mono-exponential decrease with an absorption and elimination half-life of approximately 3 h and 11 h, respectively for both treatment groups. In addition, at 72 h after the administration of [14C]-atrazine, approximately 93% of the administered radioactivity was recovered and the primary route of excretion was via the urine (67%) for both treatment groups. The feces accounted for approximately 18% of the dose, and less than 10% remained in the carcass, skin, and red blood cells (RBCs). The urine excreted in the first 24 h post-dosing contained approximately 57% of the administered radioactivity for both treatment groups. There were no appreciable differences in the metabolite distribution between treatment groups, and the major urinary metabolite of atrazine was found to be 2-chloro-4,6-diamino-1,3,5-triazine (II; 64-67%). Additionally, S-(2-amino-4-methylethylamino-1,3,5-triazin-6-yl)-mercapturi c acid (V; 13-14%), and S-(2,4-diamino-1,3,5-triazin-6-yl)-mercapturic acid (III; 9%) were tentatively identified based upon similar HPLC retention times as seen with synthesized standards. These data indicate that there are no meaningful differences in the absorption, distribution, metabolism, and excretion between rats administered only [14C]-atrazine and those administered both tridiphane and [14C]-atrazine. Therefore, it can be concluded that tridiphane has no meaningful effect on the pharmacokinetics and/or metabolism of atrazine in the rat.