Overcoming challenges in dermal and transdermal delivery of herbal therapeutics with polymeric microneedles.

Natural products are generally preferred medications owing to their low toxicity and irritancy potential. However, a good number of herbal therapeutics (HT) exhibit solubility, permeability and stability issues that eventually affect oral bioavailability. Transdermal administration has been successful in resolving some of these issues which has lead in commercialization of a few herbal transdermal products. Polymeric Microneedles (MNs) has emerged as a promising platform in transdermal delivery of HT that face problems in permeating the skin. Several biocompatible and biodegradable polymers used in the fabrication of MNs have been discussed. MNs have been exploited for cutaneous delivery of HT in management of skin ailments like skin cancer, acne, chronic wounds and hypertrophic scar. Considering the clinical need, MNs are explored for systemic delivery of potent HT for management of diverse disorders like asthma, disorders of central nervous system and nicotine replacement as it obviates first pass metabolism and elicits a quicker onset of therapeutic response. MNs of HT have found good number of aesthetic applications in topical delivery of HT to the skin. Interestingly, MNs have emerged as an attractive option as a minimally invasive diagnostic aid in sampling biomarkers from plants, skin and ocular interstitial fluid. The review updates the progress made by MN technology of HT for multiple therapeutic interventions along with the future challenges. An attempt is made to illustrate the challenging formulation strategies employed in the fabrication of polymeric MNs of HT. Efforts are on to extend the potential applications of polymeric MNs to HT for diverse therapeutic applications.

Novel topical anandamide formulation for alleviating peripheral neuropathic pain.

Peripheral neuropathy (PN) is a condition of peripheral nerve damage leading to severe pain. The first line therapies are associated with adverse psychotropic effects (PSE) and second line therapies are not efficient enough to relieve pain. There is an unmet drug need for relieving pain effectively without PSE in PN. Anandamide, an endocannabinoid activates cannabinoid receptors to relieve the pain due to peripheral neuropathy (PN). Anandamide has a very short biological half-life as they are extensively metabolized by fatty acid amide hydrolase enzyme (FAAH). Regional delivery of safe FAAH inhibitor (FI) with anandamide would be beneficial for PN without PSE. The objective of the study is to identify a safe FI and deliver the anandamide in combination with the FI topically for the management of PN. The FAAH inhibition potential of silymarin constituents was evaluated by molecular docking and in vitro studies. The topical gel formulation was developed to deliver anandamide and FI. The formulation was assessed in chemotherapeutic agent-induced PN rat models to relieve mechanical-allodynia and thermal-hyperalgesia. The molecular docking studies demonstrated that the Prime MM-GBSA free energy of silymarin constituents were in the order of silybin > isosilybin > silychristin > taxifolin > silydianin. In in vitro studies, silybin 20 µM inhibited > 61.8% of FAAH activity and increased the half-life of anandamide. The developed formulation increased permeation of anandamide and silybin across the porcine skin. Furthermore, on the application of anandamide and anandamide-silybin gel to rat paws, there was a significant increase in the pain threshold for allodynic and hyperalgesic stimulus up to 1 h and 4 h, respectively. The topical anandamide with silybin delivery approach could serve to alleviate PN efficiently and thus could minimize unwanted CNS side effects of synthetic or natural cannabinoids in patients.

Polymer coated polymeric microneedles for intravitreal delivery of dexamethasone.

The polymer coated polymeric (PCP) microneedles (MNs) is a novel approach for controlled delivery of drugs (without allowing release of the excipients) to the target site. PCP MNs was explored as an approach to deliver the drug intravitreally to minimize the risks associated with conventional intravitreal injections. The core MNs was fabricated with polyvinyl pyrrolidone K30 (PVP K30) and coating was with Eudragit E100. Preformulation studies revealed that the films prepared using Eudragit E 100 exhibited excellent integrity in the physiological medium after prolonged exposure. FTIR studies were performed to investigate the possible interaction between the API and the polymer. The PCP MNs fabricated with different drug loads (dexamethasone sodium phosphate) were subjected to in vitro drug release studies. The drug release from uncoated MNs was instantaneous and complete. On the other hand, a controlled release profile was observed in case of PCP MNs. Likewise, even in the ex vivo porcine eye model, the drug release was gradual into the vitreous humor in case of PCP MNs. The uncoated microneedles released all the drug instantaneously where the PCP MNs retarded the release up to 3 h.

Sublimation of Drugs from the Site of Application of Topical Products.

The objective of the project was to investigate the plausibility of active pharmaceutical ingredients (APIs) to undergo sublimation from topical application following evaporation of solvent. Topical formulations with different APIs were subjected to a sublimation screening test. The APIs in the selected topical products were found to undergo sublimation to a different extent. The salicylic acid topical product was found to undergo a significant loss due to sublimation. The extent of sublimation of salicylic acid was significantly greater at skin temperature compared to room temperature. When the APIs were subjected to the sublimation screening test in their neat form at 32 ± 1 °C, the natural log of the rate of sublimation decreased linearly with the standard enthalpy of sublimation of compound (R2 = 0.89). The formulation composition was found to have a significant impact on the extent of sublimation of the representative API, salicylic acid. The sublimation of APIs from the topical product was found to affect the mass balance studies in the case of the salicylic acid ointment. Furthermore, the results of the human studies agreed with the in vitro experimental results demonstrating the plausibility of loss of API due to sublimation from the site of application.

Polymer-Coated Polymeric (PCP) Microneedles for Controlled Dermal Delivery of 5-Fluorouracil.

Polymeric microneedles were prepared with Polyvinyl Pyrrolidone (PVP) K-30 using the mold casting technique. The core microneedles were coated with Eudragit E-100 by dip and spin method. The amount of 5-fluorouracil (FU) loaded in the core microneedles was 604 ± 35.4 µg. The coating thickness was 24.12 ± 1.12 µm. The objective was to deliver the 5-FU gradually in a controlled release manner at the target site in the sub-stratum corneum layer. This approach is anticipated to improve the safety and efficacy of topical melanoma treatment. The release of the drug was prolonged for up to 3 h from the polymer-coated polymeric (PCP) microneedles. The entire amount was found to release within 15 min in uncoated MNs. Likewise, the permeation of the drug from the uncoated microneedles was rapid, whereas the PCP microneedles were able to prolong the permeation up to 420 min. The PCP microneedles were subjected to stability studies at 25°C ± 2°C/60%RH, and 40°C ± 2°C/75%RH condition for 3 months. The formulations were found intact, and the release rate was not significantly different form the fresh formulation. The drug content was found to meet the acceptability criteria as well (98.12 ± 1.8% and 97.8 ± 2.1% at 25 and 40°C respectively after 3 months). Overall, this study demonstrated the feasibility of fabrication of PCP microneedles using Eudragit E100 for intraregional controlled delivery of drugs.

Effect of Lipid Vehicles on Solubility, Stability, and Topical Permeation of Delta-9-Tetrahydrocannabinol.

Delta-9-tetrahydrocannabinol (THC) is one of the most effective antinociceptive agents used in the treatment of peripheral neuropathy. THC is highly lipophilic and susceptible to thermal and oxidative degradation. Identifying appropriate solvents in which THC is stable as well as adequately solubilized is crucial in developing topical dosage forms. Lipid solvent systems are of utmost utility and relevance for formulating highly lipophilic drugs. Hence, the objective of this project was to screen the solubility of THC in lipidic excipients, monitor THC content in the selected vehicles during stability, and study the influence of these excipients on permeation of THC across skin. The solubility of THC in liquid lipid excipients was in the range of 421 to 500 mg/g. The solubility of THC in solid lipid excipients was in the range of 250 to 750 mg/g. THC in its neat form was poorly stable, but when dissolved in lipid-based excipients, its stability improved significantly. THC in lipid excipients was more stable at 4 ± 3°C compared to samples stored at 25 ± 2°C. The antioxidants (butylated hydroxytoluene and ascorbyl palmitate) used in the excipients further improved the stability of THC. The results demonstrated that the liquid and solid lipid excipients used in the study could solubilize THC freely and mitigate the degradation of THC significantly. The binary combination of lipid excipients enhanced THC skin permeation and retention, demonstrating the potential for topical formulation development of THC.

Development and Validation of HPLC Method for Efinaconazole: Application to Human Nail Permeation Studies.

Efinaconazole is the first azole derivative approved by FDA for the topical treatment of onychomycosis. The objective of present study was to develop and validate HPLC method for estimation of efinaconazole in ex vivo human nail permeation study samples. The chromatographic analysis was performed on a HPLC system equipped with diode array detector. The efinaconazole and internal standard (IS) were extracted from the human nail samples by using the protein precipitation method. The samples were injected on to 5 µm Polar C18 100Å, 4.6 mm × 150 mm column. The mobile phase consisted of 0.01 M potassium dihydrogen phosphate: acetonitrile (36:64) and eluent was monitored at 205 nm. The chromatographic separation of drug and analyte was achieved using isocratic elution at flow rate of 1 mL/min with a total run time of 15 min. The efinaconazole and IS were eluted at 6.4 ± 0.5 and 8.3 ± 0.5 min, respectively. The developed method was validated as per FDA guidelines, and the results met with acceptance criteria. The method developed was specific, and the analyte concentrations were linear at range of 50 to 10000 ng/mL (R2 ≥ 0.9981). The validated HPLC method was applied for quantifying efinaconazole in human nail permeation study samples. The permeation of efinaconazole was increased by twofolds with Labarfac CC (15135.4 ± 2233.9 ng/cm2) compared to formulations containing Transcutol P (6892.0 ± 557.6 ng/cm2) and Labrasol (7266.1 ± 790.6 ng/cm2). The study results demonstrate that developed efinaconazole HPLC method can be employed for formulation evaluation and clinical studies.

Chemotherapeutic Agent-Induced Vulvodynia, an Experimental Model.

Vulvodynia is a chronic clinical condition associated with vulvar pain that can impair the sexual, social, and psychological life of women. There is a need for more research to develop novel strategies and therapies for the treatment of vulvodynia. Vulvodynia in experimental animal models induced via infections, allergens, and diabetes are tedious and with lessor induction rate. The objective of the study was to explore the possibility of inducing vulvodynia using a chemotherapeutic agent in a rodent model. Paclitaxel is commonly used in treating breast and ovarian cancer, whose dose-limiting side effect is peripheral neuropathy. Studies have shown that peripheral neuropathy is one of the etiologies for vulvodynia. Following paclitaxel administration (2 mg/kg i.p.), the intensity of vulvar hypersensitivity was assessed using a series of von Frey filaments (0.008 to 1 g) to ensure the induction of vulvodynia. Vulvodynia was induced from day 2 and was well sustained for 11 days. Furthermore, the induced vulvodynia was validated by investigating the potentiation of a flinch response threshold, upon topical application and systemic administration of gabapentin, a commonly used medication for treating neuropathic pain. The results demonstrate that vulvodynia was induced due to administration of paclitaxel. The fact that chemotherapeutic agent-induced vulvodynia was responsive to topical and parenterally administered gabapentin provides validity to the model. The study establishes a new, relatively simple and reliable animal model for screening drug molecules for vulvar hypersensitivity.

A Rapid Tool to Optimize Process Variables for Continuous Manufacturing of Metronidazole Ointment Using Melt Extrusion Technique.

The use of hot-melt extrusion (HME) technique in the preparation of semi-solid products offers several advantages over conventional processes. However, the optimization of the technique for preparation of semi-solid pharmaceuticals is challenging due to involvement of ingredients with different physical properties. Hence, a simple tool to optimize the mixing of ingredients that results in a target ratio and drug content uniformity is utmost important. In this study, a handheld colorimeter has been explored to optimize the process variables of twin screw processor for preparation of hydrophilic PEG-based ointment. The process parameters which were optimized with use of handheld colorimeter have been used for preparation of polyethylene glycol-based metronidazole ointment. The metronidazole ointment prepared by twin screw processor was compared with commercially available metronidazole gel for in vitro release testing and ex vivo permeation. The flux, ex vivo bioavailability, and Tmax of polyethylene glycol-based metronidazole ointment was found to be similar to that of marketed metronidazole gel.

Topical Pilocarpine Formulation for Diagnosis of Cystic Fibrosis.

Cystic fibrosis is diagnosed in infants by estimating the levels of chloride ions present in the sweat induced by iontophoresis of pilocarpine solution. Elevated levels of chloride (≥60 mMol/L) in sweat are indicative of cystic fibrosis. However, the iontophoretic method of delivering pilocarpine is cumbersome and usually is associated with several side effects such as skin burn, skin rashes, erythema, and so forth. The objective of this study was therefore to develop a topical formulation that delivers adequate amount of pilocarpine. The drug delivery of formulation was compared with iontophoresis of aqueous solution of pilocarpine nitrate in vitro using porcine skin model. The pilocarpine levels in the skin exposed to topical pilocarpine solution under mild hyperthermia was 152.04 ± 52.23 µg/cm2 after 10 min of application, whereas it was 97.05 ± 27.93 µg/cm2 in the skin after 10 min of iontophoresis. The topical formulation was subjected to clinical evaluation to assess the efficacy of the product to induce sweat production. The average amount of the sweat secreted on application of topical formulation was found to be 77.28 ± 18.97 mg. Based on these results, it was found that the topical formulation was successful in delivering pilocarpine and to stimulate sweat secretion.

Evaluation of soluble fentanyl microneedles for loco-regional anti-nociceptive activity.

The use of opioids for treating acute and chronic pain condition is a common clinical practice. When delivered systemically, the analgesic activity is mediated through the central pathway, which although effective, leads to various adverse effects such as dependence, abuse and respiratory depression. Fentanyl is an opioid analgesic that is available as injection and transdermal patch products for the management of acute and chronic pain. These products require stringent regulatory controls and label warnings on disposal due to the abuse potential associated. This research project evaluated the regional antinociceptive efficacy of fentanyl delivered from soluble microneedles. The microneedle patches were formulated with relatively less drug loading as compared to patches intended for systemic delivery and were tested for their antinociceptive activity in rats by measuring the paw withdrawal latency when exposed to a thermal stimulus. The results indicate that regional delivery of fentanyl mediated through soluble microneedles provides an effective antinociceptive activity. The onset of analgesic activity was faster with microneedle patch (0.5 h) when compared to the adhesive dermal patch (6 h). This study thus demonstrates the effectiveness of microneedle mediated pain management for immediate pain relief.

Antiallodynic and Antihyperalgesic Activities of Fentanyl-Loaded Dermal Clay Dressings in Rat Model of Second-Degree Burn Injury.

Second-degree burn injury is the most common type of burn injury, which usually takes 2-3 weeks for complete healing. However, such patients suffer with intense pain associated with development of hyperalgesia and allodynia. Here, we prepare a silver clay patch using montmorillonite clay, betaine, and silver nitrate. Later, the silver clay patches were loaded with fentanyl. Furthermore, the patches were fabricated into burn wound dressings. The dressings were first subjected to ex vivo skin penetration studies and were later evaluated for thermal hyperalgesia and mechanical allodynia using second-degree burn injury rodent model. Our results show that application of fentanyl-loaded dermal clay (FLDC) dressings for 3 h showed significant increase of paw withdrawal latency (p <0.001) against hyperalgesia starting from 30 min after removal of patch to up to 6 h. Similarly, the FLDC dressings also potentiated the paw withdrawal threshold for up to 4 h after application (p <0.001). From these studies, we can conclude that FLDC dressings are ideal topical formulations for better management of pain in second-degree burns.

Synthesis and Anti-hyperlipidemic Activity of 3H-benzo [4, 5] thieno [2, 3-d] [1, 2, 3] triazin-4-ones: Possible Mechanism of Altered Lipid Metabolism.

OBJECTIVES: The present study was aimed to evaluate the anti-hyperlipidemic activity of newly synthesized tricyclic benzothieno 1, 2, 3-triazine derivatives namely CP-1 (3-(methyl)- 5,6,7,8-tetrahydro,3H-benzo[4,5] thieno [2,3-d][1,2,3] triazin-4-one), CP-2 (3-(ethyl)- 5,6,7,8-tetrahydro,3H-benzo[4,5] thieno [2,3-d][1,2,3] triazin-4-one) and CP-6 (3-(2-chloro phenyl)-5,6,7,8-tetrahydro,3H-benzo[4,5] thieno [2,3-d][1,2,3] triazin-4-one) against dexamethasone and Triton WR-1339-induced hyper-lipidemia in rats. METHODS: Anti-hyperlipidemic activity of the test compounds were evaluated against dexamethasone (10 mg/kg, subcutaneous [s.c.]) and Triton WR-1339 (200 mg/kg, intraperitoneal [i.p]) induced hyperlipidemia in rats. RESULTS: Administration of single dose of Triton WR-1339 (200 mg/kg i.p) and dexamethasone (10 mg/kg s.c.) for 8 consecutive days to adult wistar rats caused severe hyperlipidemia characterized by marked increase in serum cholesterol, LDL-C, VLDL-C and triglyceride levels along with an increase in atherogenic index. Serum HDL-C levels were decreased significantly compared to normal control. Pretreatment with Atorvastatin (10 mg/kg, p.o.), CP-1 (25 and 50 mg/kg), CP-2 (25 and 50 mg/kg) and CP-6 (25 and 50 mg/kg) showed significant and dose-dependent protection against dexamethasone and Triton WR-1339-induced hyperlipidemia in rats by maintaining serum total cholesterol, LDL-C, VLDL-C and HDL-C levels within the normal range. Also, a significant decrease in atherogenic index was observed. The anti-hyperlipidemic effect of CP-6 was comparable with reference standard Atorvastatin. Furthermore, CP-6 was found to be more potent than CP-1 and CP-2. CONCLUSION: These findings suggest that CP-1, CP-2 and CP-6 possess significant anti-hyperlipidemic activity against experimental animal models of hyperlipidemia.

Synthesis and antihistaminic activity of 3H-benzo [4,5] thieno [2,3-d][1,2,3] triazin-4-ones.

In the present study the antihistaminic activity of tricyclic benzothieno 1,2,3-triazine derivatives namely CP-3 (3-(phenyl)-5,6,7,8-tetrahydro,3H-benzo[4,5] thieno [2,3-d][1,2,3] triazin-4-one), CP-5 (3-(3-methyl phenyl)-5,6,7,8-tetrahydro,3H-benzo[4,5] thieno [2,3-d][1,2,3] triazin-4-one) and CP-8 (3-(4-chloro phenyl)-5,6,7,8-tetrahydro,3H-benzo[4,5] thieno [2,3-d][1,2,3] triazin-4-one) were evaluated using in vitro (isolated guinea pig ileum) and in vivo (bronchodilator activity in guinea pigs) models and the sedative potential of the test compounds were evaluated using actophotometer in mice. In in vitro antihistaminic study, the CP-3, CP-5, CP-8 and chlorpheniramine maleate (CPM) have shown a rightward shift in concentration response curve (CRC) of histamine with a change in EC50 values of histamine in all the four tissue preparations. The slope obtained in the schild plot indicated that CP-5, CP-8 and CPM were competitive in nature for H1-receptors. However, CP-3 has shown non-competitive antagonism. In in vivo antihistaminic study, the CP-3, CP-5, CP-8 and CPM have shown mean increase in exposition time against histamine challenge compared to control group (p < 0.001). All the test drugs (10 mg/kg) and CPM (2 mg/kg) have offered a significant (p < 0.001) protection against preconvulsive dyspnoea (PCD) compared to control. In conclusion, all the test drugs have shown very good antihistaminic activity and the test drugs have very little sedative action compared to CPM.

Antidiarrheal effect of fractions from stem bark of Thespesia populnea in rodents: Possible antimotility and antisecretory mechanisms.

OBJECTIVE: To evaluate antidiarrheal activity of the fractions of aqueous extract from stem barks of Thespesia populnea (Malvaceae). METHODS: From the aqueous extract three fractions namely ethyl acetate fraction (EAF), methanolic fraction (MF) and residue fraction (RF) were made and studied for antidiarrheal activity. Antidiarrheal activity of the fractions were evaluated in castor oil induced diarrhea, prostaglandin E(2) (PG-E(2)) induced diarrhea and charcoal meal test as in vivo models and the most potent fraction was further evaluated with in vitro models to determine the possible antimotility effect. RESULTS: In castor oil induced diarrhea model, the RF (10, 25, 50 and 100 mg/kg, po.) and MF (100 mg/kg, po.) has significantly reduced the cumulative wet faecal mass, where as the EAF have not shown any significant antidiarrheal activity, RF was found to be more potent than MF. Based on these results and percentage yield, only RF was evaluated in PG-E(2) induced enteropooling and charcoal meal test. RF (10, 25 and 50 mg/kg) had shown significant inhibition of PG-E(2) induced secretions (antisecretory) and decreased the movement of charcoal in charcoal meal test indicating its antimotility activity. Furthermore, RF has showed significant inhibition of acetylcholine, histamine and BaCl(2) induced contractions on rat colon, guinea pig ileum and rabbit jejunum with EC(50) values of 241.7, 303.1 and 286.1 µg/mL, respectively indicating the antimotility effect of RF. The phytochemical analysis of RF showed presence of gums and mucilages and the possible mechanism may be the combination inhibition of elevated prostaglandin biosynthesis and reduced propulsive movement of the intestine. CONCLUSIONS: RF possesses good antidiarrheal activity comparing with other two fractions and the possible mechanism thought to be associated with combination of antisecretory and antimolity.