The in vitro and in vivo effects of a fast-dissolving mucoadhesive bi-layered strip as topical anesthetics

Physiology of pregnancy and oral local anesthesia considerations

Background

Safe and effective local anesthesia is a prerequisite for emergency oral surgeries and most dental treatments. Pregnancy is characterized by complex physiological changes, and increased sensitivity to pain. Pregnant women are particularly vulnerable to oral diseases, such as caries, gingivitis, pyogenic granuloma and third molar pericoronitis. Maternally administered drugs can affect the fetus through the placenta. Therefore, many physicians and patients are reluctant to provide or accept necessary local anesthesia, which leads to delays in the condition and adverse consequences. This review is intended to comprehensively discuss the instructions for local anesthesia in the oral treatment of pregnant patients.

Methodology

An in-depth search on Medline, Embase, and the Cochrane Library was performed to review articles concerned with maternal and fetal physiology, local anesthetic pharmacology, and their applications for oral treatment.

Results

Standard oral local anesthesia is safe throughout the pregnancy. At present, 2% lidocaine with 1:200,000 epinephrine is considered to be the anesthetic agent that best balances safety and efficacy for pregnant women. Maternal and fetal considerations must be taken into account to accommodate the physiological and pharmacological changes in the gestation period. Semi-supine position, blood pressure monitoring, and reassurance are suggested for high-risk mothers to reduce the risk of transient changes in blood pressure, hypoxemia, and hypoglycemia. For patients with underlying diseases, such as eclampsia, hypertension, hypotension, and gestational diabetes, the physicians should use epinephrine cautiously and control the dose of anesthetic. New local anesthesia formulations and equipment, which contribute to minimizing injection pain and relieving the anxiety, have and are being developed but remain understudied.

Conclusions

Understanding the physiological and pharmacological changes during pregnancy is essential to ensure the safety and efficiency of local anesthesia. Optimal outcomes for the mother and fetus hinge on a robust understanding of the physiologic alterations and the appropriate selection of anesthetic drugs and approaches.

A mucoadhesive biodissolvable thin film for localized and rapid delivery of lidocaine for the treatment of vestibulodynia

Vestibulodynia (VBD), an idiopathic pain disorder characterized by erythema and pain of the vulvar vestibule (the inner aspect of the labia minora and vaginal opening), is the most common cause of sexual pain for women of reproductive age. Women also feel discomfort with contact with clothing and tampon use. As most women with this disorder only have pain with provocation of the tissue, topical anesthetics applied to the vestibule are the current first line treatment for temporary pain relief. Treatment options are limited due to anatomical constraints of the vestibular region, poor drug retention time, imprecise dosing, leakage, and overall product messiness. In this study we report a novel approach to treatment of VBD using thin film designed to fit the vulvar vestibule and deliver lidocaine locally. Two use cases for VBD treatment were identified 1) rapid drug release (<5 min), for use prior to intercourse and 2) long-acting release (≥120 min) for prolonged use and relief throughout the day. Cellulose-based mucoadhesive thin films were fabricated using a solvent casting method. Three polymers including hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), and hydroxypropylmethycellulose (HMPC), were selected owing to their biocompatibility and ideal properties for film casting. Films casted with HEC, HPC, and HPMC exhibited mucoadhesive properties relative to a control, with the highest mucoadhesive force recorded for films casted with HPC. Effect of media volume, pH, presence of mucin and presence of drug on film dissolution rates were investigated. Dissolution rates were independent of media volume, media pH or drug presence, whereas faster dissolution rates were obtained for all films in presence of mucin. In vitro lidocaine release kinetics were influenced by polymer type, percent drug loading and film casting thickness. Lidocaine release was based on a diffusion mechanism rather than through film dissolution and faster release (∼5 min) was observed for HEC films compared HPC films (∼120 min). Higher drug loading and film thickness resulted in slower and more prolonged release kinetics of lidocaine. All films were biocompatible and exhibited good mechanical properties. Two film formulations (9% w/w HPC with 12% w/w LHC, 5% w/w HEC with 6% w/w LHC) were optimized to meet the two use case scenarios for VBD treatment and moved into in vivo testing. In vivo testing demonstrated the safety of the films in BALB/c mice, and the pharmacokinetic analysis demonstrated the delivery of lidocaine primarily to the vaginal tissue. We demonstrate the ability to develop a mucoadhesive, biodissolvable thin film and fine-tune drug release kinetics to optimize local delivery of lidocaine to the vulva.

Microwave-Assisted Fabrication of Mesoporous Silica-Calcium Phosphate Composites for Dental Application

Herein, the microwave-assisted wet precipitation method was used to obtain materials consisting of mesoporous silica (SBA-15) and calcium orthophosphates (CaP). Composites were prepared through immersion of mesoporous silica in different calcification coating solutions and then exposed to microwave radiation. The composites were characterized in terms of molecular structure, crystallinity, morphology, chemical composition, and mineralization potential by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). The application of microwave irradiation resulted in the formation of different types of calcium orthophosphates such as calcium deficient hydroxyapatite (CDHA), octacalcium phosphate (OCP), and amorphous calcium phosphate (ACP) on the SBA-15 surface, depending on the type of coating solution. The composites for which the progressive formation of hydroxyapatite during incubation in simulated body fluid was observed were further used in the production of final pharmaceutical forms: membranes, granules, and pellets. All of the obtained pharmaceutical forms preserved mineralization properties.

Technology of Orodispersible Polymer Films with Micronized Loratadine-Influence of Different Drug Loadings on Film Properties

The production of orodispersible films (ODFs) with suspended insoluble drug substances is still a challenge, mainly due to the difficulty associated with achieving a proper homogeneity and mechanical properties of the films. Hypromellose (HPMC) and a mixture of polyvinyl alcohol (AP) and povidone (PVP) were compared in terms of their suitability for ODFs incorporating suspended micronized loratadine (LO) in a concentration range of 10%–40%. In a planetary mixer (Thinky), a uniform dispersion of LO in an aqueous viscous casting solution was obtained. The suspended LO particles caused dose-dependent changes in the viscosity of the casting mass and affected the mechanical quality of ODFs. Drug concentrations higher than 30% reduced the film flexibility and tear resistance, depending on the polymer type. LO films with a thickness of 100 µm disintegrated within 60-100 s, with no significant influence of the LO content in the range 10%–30%. HPMC films, regardless of the drug concentration, met the pharmacopoeial requirements regarding the uniformity of the drug content. AP/PVP films were too elastic, and the drug content uniformity was not achieved. The conclusion is that, using an HPMC matrix, it is possible to obtain a high load of a poorly water-soluble drug (30% of dry film mass corresponds to a dose of 5 mg per 1.5 cm²) in ODFs characterized by proper physical characteristics.

Premium ethylcellulose polymer based architectures at work in drug delivery

Premium ethylcellulose polymers are hydrophobic cellulose ether based biomaterials widely employed as biocompatible templates for the design of novel drug delivery systems. They are classified as United States Food and Drug Administration Generally-Recognized-As-Safe chemical substances and have been extensively utilized within the biomedical and pharmaceutical industries for over half a century. They have so far demonstrated the potential to modulate and improve the physiological performance of bioactives leading to the desired enhanced prophylactic and therapeutic outcomes. This review therefore presents a scholarly survey of inter-disciplinary developments focused on the functionalities of ethylcellulose polymers as biomaterials useful for the design of smart delivery architectures for relevant pharmacotherapeutic biomedical applications. Emphasis was placed on evaluating scientific resources related to recent advancements and future directions associated with its applications as delivery systems for drugs and biologics within the past decade thus complementing other specialized reviews showcasing the theme.

Efficacy of a Light-cured Tetracaine-based Anesthetic Gel for Rubber Dam Clamp Placement: A Triple-blind Randomized Clinical Trial

OBJECTIVES

To evaluate the efficacy of a new light-cured anesthetic gel for pain control in adults undergoing rubber dam isolation for the restorative treatment of noncarious cervical lesions (NCCLs).

METHODS AND MATERIALS

This study was a randomized, split-mouth, triple-blind, controlled trial. The sample comprised 50 adults with at least one pair of NCCLs located in the same arch but on opposite sides. Simple randomization defined the tooth to receive the light-cured tetracaine-based anesthetic gel or the placebo gel. After cotton roll isolation, the gels were applied in the gingival tissue around the tooth with the aid of the applicator tip of a syringe, left in place for 15 seconds, and light-cured for 15 seconds. Then, a #212 clamp was positioned on the tooth. If the patient reported pain, the clamp was removed, the patient filled out a pain intensity form (a 0-10 visual analog scale [VAS] and a 0-4 verbal rating scale [VRS]) and an injectable anesthetic was applied before rubber dam isolation for the restorative procedure. The absolute risk, intensity of pain, and need for rescue anesthesia were analyzed by the McNemar test and the Wilcoxon signed rank test (α=5%).

RESULTS

The odds ratio [OR] for pain (OR=3.5; 95% confidence interval [CI]=1.1 to 14.6; p=0.03) showed lower reports of pain for the light-cured anesthetic gel. One in five patients will benefit from placement of the light-cured anesthetic gel. On average, pain intensity was one VAS unit lower in those using the light-cured anesthetic gel than in those using the placebo gel. For the VRS, the pain intensity for the light-cured anesthetic gel was 0.4 units lower than the pain intensity for the placebo gel (95% CI=-0.9 to 0.07). The OR for rescue anesthesia was 2.5 (95% CI=0.7 to 10.9; p=0.18).

CONCLUSIONS

The light-cured, tetracaine-based anesthetic gel reduced the absolute risk of pain by 20% in NCCLs.

Ethylcellulose-A Pharmaceutical Excipient with Multidirectional Application in Drug Dosage Forms Development

Polymers constitute the most important group of excipients utilized in modern pharmaceutical technology, playing an essential role in the development of drug dosage forms. Synthetic, semisynthetic, and natural polymeric materials offer opportunities to overcome different formulative challenges and to design novel dosage forms for controlled release or for site-specific drug delivery. They are extensively used to design therapeutic systems, modify drug release, or mask unpleasant drug taste. Cellulose derivatives are characterized by different physicochemical properties, such as swellability, viscosity, biodegradability, pH dependency, or mucoadhesion, which determine their use in industry. One cellulose derivative with widespread application is ethylcellulose. Ethylcellulose is used in pharmaceutical technology as a coating agent, flavoring fixative, binder, filler, film-former, drug carrier, or stabilizer. The aim of this article is to provide a broad overview of ethylcellulose utilization for pharmaceutical purposes, with particular emphasis on its multidirectional role in the development of oral and topical drug dosage forms.

Formulation and Optimization of Oral Mucoadhesive Patches of Myrtus Communis by Box Behnken Design

Purpose: Recurrent aphthous stomatitis (RAS) is the most common painful ulcerative disease of oral mucosa happening in ~20% of people. Aimed to develop Myrtus communis L. (Myrtle) containing oral patches, we applied box-behnken design to evaluate the effect of polymers such as Polyvinyl pyrrolidone (PVP), Gelatin, Methylcellulose (MC) and Pectin. Methods: The patches properties such as tensile strength, folding endurance, swelling index, thickness, mucoadhesive strength and the pattern of myrtle release were evaluated as dependent variables. Then, the model was adjusted according to the best fitted equation with box behnken design. Results: The results indicated that preparation of myrtle patch with hydrophilic polymers showed the disintegration time up to 24h and more. Using of polyvinyl pyrrolidone as a water soluble polymer and a pore-former polymer led to faster release of soluble materials from the patch to 29 (min-1). Also it decreases swelling index by increasing the patch disintegration. Gelatin and Pectin, with rigid matrix and water interaction properties, decreased the swelling ratio. Pectin increased the tensile strength, but gelatin produced an opposite effect. Thinner Myrtle patch (about 28µm) was obtained by formulation of methyl cellulose with equal ratio with polyvinyl pyrrolidone or gelatin. Conclusion: Altogether, the analysis showed that the optimal formulation was achieved with of 35.04 mg of Gelatin, 7.22 mg of Pectin, 7.20 mg of polyvinyl pyrrolidone, 50.52 mg of methyl cellulose and 20 mg of Myrtle extract.