Pharmacological Challenge Models in Clinical Drug Developmental Programs

Early phase clinical research for drug development requires the investigation of safety, tolerability and efficacy of novel compounds. The latter is hampered by the absence of the disorder in healthy volunteers, which is why challenge models are often applied in order to demonstrate ‘proof of pharmacology.’ These challenge models can often be translatable from animal work and can inform the drug developer which dose, dosing regimen or application frequency should be selected prior to phase II studies in the target population. Furthermore, these challenge models represent well-controlled settings to perform activity screening of the compound. The following skin challenge models will be reviewed in this chapter: inflammation induced by Toll-like receptor agonists such as imiquimod, KLH challenge, UV-B irradiation and histamine

Needle-free electronically-controlled jet injector treatment with bleomycin and lidocaine is effective and well-tolerated in patients with recalcitrant keloids

Objectives: The treatment of recalcitrant keloids is challenging. Although intralesional bleomycin using conventional needle injectors (CNI) is effective, it has important drawbacks, such as the need for repetitive and painful injections. Therefore, we aimed to evaluate the effectiveness, tolerability and patient satisfaction of intralesional bleomycin with lidocaine administered with a needle-free electronically-controlled pneumatic jet-injector (EPI) in recalcitrant keloids. Methods: This retrospective study included patients with recalcitrant keloids who had received three intralesional EPI-assisted treatments with bleomycin and lidocaine. Effectiveness was assessed using the Patient and Observer Scar Assessment Scale (POSAS) at baseline and four to six weeks after the third treatment. Additionally, treatment related pain scores numeric rating scale, adverse effects, patient satisfaction and Global Aesthetic Improvement Scale (GAIS) were assessed. Results: Fifteen patients with a total of &gt;148 recalcitrant keloids were included. The median total POSAS physician- and patient-scores were respectively 40 and 41 at baseline, and reduced with respectively 7 and 6-points at follow-up (p &lt; 0.001; p &lt; 0.001). The median pain scores during EPI-assisted injections were significantly lower compared to CNI-assistant injections, (2.5 vs. 7.0, respectively (p &lt; 0.001)). Adverse effects were mild. Overall, patients were “satisfied” or “very satisfied” with the treatments (14/15, 93.3%). The GAIS was “very improved” in one patient, “improved” in nine patients and “unaltered” in four patients. Conclusions: EPI-assisted treatment with bleomycin and lidocaine is an effective, well tolerated, patient-friendly alternative for CNI in patients with recalcitrant keloid scars. Randomized controlled trials are warranted to confirm our findings and improve the clinical management of recalcitrant keloids.</p

Needle-Free Jet Injector-Assisted Triamcinolone Treatment of Keloids and Hypertrophic Scars is Effective and Well Tolerated in Children

Background: Keloids and hypertrophic scars can cause severe pain, pruritus, and psychological distress. Conventional intralesional corticosteroid treatment with needle injections remains challenging, especially in children with needle phobia. Objective: We aimed to evaluate the effectiveness, tolerability, and patient satisfaction of intralesional treatment with triamcinolone acetonide using a needle-free electronic pneumatic jet injector in children with keloids and hypertrophic scars. Methods: A retrospective study was performed in children with keloids and hypertrophic scars who received intralesional triamcinolone acetonide treatments using an electronic pneumatic jet injector. Effectiveness was evaluated using the Patient and Observer Scar Assessment Scale and Global Aesthetic Improvement Score at follow-up versus baseline. Tolerability was assessed with reported adverse effects and injection-related pain using a visual analog scale. Satisfaction questionnaires were used to evaluate treatment-related patient satisfaction. Results: Six female patients and five male patients aged 5–17 years, with a total of &gt;118 keloids or hypertrophic scars were included. Electronic pneumatic jet injector treatment led to a significant reduction in the total Patient and Observer Scar Assessment Scale observer and patient scores compared with baseline, with a median reduction of 28.9% and 23.8%, respectively (p = 0.005; p = 0.009). Median visual analog scale pain scores for electronic pneumatic jet injector treatment were significantly lower compared with needle injections, 3.0 versus 7.0, respectively (p = 0.027). No severe adverse effects were reported. Overall, 6 patients were ‘satisfied’ and five patients were ‘very satisfied’ with the treatment. Conclusions: Electronic pneumatic jet injector-assisted intralesional triamcinolone acetonide is an effective and well-tolerated treatment for keloids and hypertrophic scars in children. It should be considered as an alternative non-traumatic delivery method, especially in children with needle phobia or severe pain during previous needle injections.</p

Needle-Free Jet Injector-Assisted Triamcinolone Treatment of Keloids and Hypertrophic Scars is Effective and Well Tolerated in Children

Background: Keloids and hypertrophic scars can cause severe pain, pruritus, and psychological distress. Conventional intralesional corticosteroid treatment with needle injections remains challenging, especially in children with needle phobia. Objective: We aimed to evaluate the effectiveness, tolerability, and patient satisfaction of intralesional treatment with triamcinolone acetonide using a needle-free electronic pneumatic jet injector in children with keloids and hypertrophic scars. Methods: A retrospective study was performed in children with keloids and hypertrophic scars who received intralesional triamcinolone acetonide treatments using an electronic pneumatic jet injector. Effectiveness was evaluated using the Patient and Observer Scar Assessment Scale and Global Aesthetic Improvement Score at follow-up versus baseline. Tolerability was assessed with reported adverse effects and injection-related pain using a visual analog scale. Satisfaction questionnaires were used to evaluate treatment-related patient satisfaction. Results: Six female patients and five male patients aged 5–17 years, with a total of &gt;118 keloids or hypertrophic scars were included. Electronic pneumatic jet injector treatment led to a significant reduction in the total Patient and Observer Scar Assessment Scale observer and patient scores compared with baseline, with a median reduction of 28.9% and 23.8%, respectively (p = 0.005; p = 0.009). Median visual analog scale pain scores for electronic pneumatic jet injector treatment were significantly lower compared with needle injections, 3.0 versus 7.0, respectively (p = 0.027). No severe adverse effects were reported. Overall, 6 patients were ‘satisfied’ and five patients were ‘very satisfied’ with the treatment. Conclusions: Electronic pneumatic jet injector-assisted intralesional triamcinolone acetonide is an effective and well-tolerated treatment for keloids and hypertrophic scars in children. It should be considered as an alternative non-traumatic delivery method, especially in children with needle phobia or severe pain during previous needle injections.</p

Efficacy and safety of needle-free jet injector-assisted intralesional treatments in dermatology—a systematic review

Needle-free jet injectors are used for the intralesional treatment of various dermatological indications. However, a systematic review that evaluates the efficacy and safety of these treatments has not been published. The objectives of this study are to evaluate the efficacy and safety of needle-free jet injections for dermatological indications and to provide evidence-based treatment recommendations. An electronic literature search was conducted in April 2022. Two reviewers independently selected studies based on predefined criteria and performed a methodological quality assessment using the Cochrane Collaborations risk-of-bias 2.0 assessment tool and Newcastle–Ottawa Scale. Thirty-seven articles were included, involving 1911 participants. Dermatological indications included scars, alopecia areata, hyperhidrosis, nail diseases, non-melanoma skin cancer, common warts, local anesthesia, and aesthetic indications. Keloids and other types of scars (hypertrophic, atrophic, and burn scars) were investigated most frequently (n = 7). The included studies reported favorable efficacy and safety outcomes for intralesional jet injector-assisted treatment with triamcinolone acetonide/hexacetonide, 5-fluorouracil, bleomycin, or hyaluronic acid. Two high-quality studies showed good efficacy and tolerability of intralesional jet injections with a combination of 5-fluorouracil and triamcinolone acetonide in hypertrophic scars and with saline in boxcar and rolling acne scars. No serious adverse reactions and good tolerability were reported in the included studies. Overall, the methodological quality of the included studies was low. Limited evidence suggests that needle-free jet injector-assisted intralesional treatment is efficacious and safe for hypertrophic and atrophic acne scars. More well-powered RCTs investigating the efficacy and safety of jet injector treatment in dermatology are warranted to make further evidence-based recommendations. Graphical Abstract: [Figure not available: see fulltext.]