Topical antimicrobial agents in dermatology

Novel SmartReservoirs for hydrogel-forming microneedles to improve the transdermal delivery of rifampicin

Hydrogel-forming microneedles (HF-MNs) are composed of unique cross-linked polymers that are devoid of the active pharmaceutical ingredient (API) within the microneedle array. Instead, the API is housed in a reservoir affixed on the top of the baseplate of the HF-MNs. To date, various types of drug-reservoirs and multiple solubility-enhancing approaches have been employed to deliver hydrophobic molecules combined with HF-MNs. These strategies are not without drawbacks, as they require multiple manufacturing steps, from solubility enhancement to reservoir production. However, this current study challenges this trend and focuses on the delivery of the hydrophobic antibiotic rifampicin using SmartFilm-technology as a solubility-enhancing strategy. In contrast to previous techniques, smart drug-reservoirs (SmartReservoirs) for hydrophobic compounds can be manufactured using a one step process. In this study, HF-MNs and three different concentrations of rifampicin SmartFilms (SFs) were produced. Following this, both HF-MNs and SFs were fully characterised regarding their physicochemical and mechanical properties, morphology, Raman surface mapping, the interaction with the cellulose matrix and maintenance of the loaded drug in the amorphous form. In addition, their drug loading and transdermal permeation efficacy were studied. The resulting SFs showed that the API was intact inside the cellulose matrix within the SFs, with the majority of the drug in the amorphous state. SFs alone demonstrated no transdermal penetration and less than 20 ± 4 μg of rifampicin deposited in the skin layers. In contrast, the transdermal permeation profile using SFs combined with HF-MNs (i.e. SmartReservoirs) demonstrated a 4-fold increase in rifampicin deposition (80 ± 7 μg) in the skin layers and a permeation of approx. 500 ± 22 μg. Results therefore illustrate that SFs can be viewed as novel drug-reservoirs (i.e. SmartReservoirs) for HF-MNs, achieving highly efficient loading and diffusion properties through the hydrogel matrix.

Bioactivity of Mupirocin Nanoparticle-Loaded Hydrogel against Methicillin-Resistant Staphylococcus aureus (MRSA)

This novel study investigated the loading of mupirocin nanoparticles into a hydrogel which was expected to enhance the antibacterial activity of mupirocin. The inhibition of isoleucyl-tRNA synthetase and global gene expression in methicillin-resistant Staphylococcus aureus (MRSA) by the mupirocin nanoparticle-loaded hydrogel (MLH) and by pure mupirocin was compared. MLH and mupirocin rapidly inhibited the growth of bacterial populations after 1 h of treatment. At 12 h, mupirocin and MLH inhibited isoleucyl-tRNA synthetase in MRSA. Transcriptome profiles of MRSA showed that gene expression alterations after treatment with mupirocin were similar to those after treatment with MLH at MICs. These alterations included changes to DNA transcription, translation, and replication pathways, and the fold changes in these genes decreased more rapidly with MLH than with mupirocin only after 1 h of treatment. MLH released the mupirocin from the nanoparticles and hydrogel systems and then the drug permeated the cell wall and bound to bacterial isoleucyl-tRNA synthetase. The research also showed that MLH could be further developed for use in clinics for infected wounds.

Analytical Method Development and Validation for Simultaneous Determination of Simvastatin and Mupirocin Using Reverse-Phase High-pressure Liquid Chromatographic Method

Objectives

This study was aimed to develop and validate the use of reverse-phase high pressure liquid chromatographic method for the estimation of simvastatin (SIM) and mupirocin (MUP) simultaneously.

Materials and Methods

The chromatographic method developed is optimized for flow rate with the column, solvent, and buffer used and mobile phase ratio, molarity, and pH. The validation of the optimized method and the forced degradation studies of both drugs (under acidic, alkaline, oxidation, heat, light, and neutral conditions) were conducted following the The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines.

Results

Kromasil C18 column (250 mm × 4.6 mm, 5 µm) with ultraviolet detection at 224 nm and acetonitrile/phosphate buffer (30 mM, 70:30 v/v, pH 3.5; adjustment done using orthophosphoric acid) as mobile phase at a flow rate of 1.1 mL/min were observed to provide a good resolution for MUP and SIM at retention times of 2.32±0.008 and 13.55±0.254 min, respectively, with high accuracy (percent recovery was 99.69±0.82 for MUP and 101.10±0.02 for SIM) and linearity in the range of 5-30 µg/mL (r²: 0.9969 for MUP and r²: 0.9959 for SIM). The diagnostic limit and the lower limit of determination were 0.771±0.234 and 2.338±0.246 μg/mL for MUP and 0.595±0.282 and 1.803±0.334 µg/mL for SIM, respectively. The validated method was used to understand the degradation behavior of both drugs after the forced degradation studies.

Conclusion

The analytical method developed is determined to be specific, sensitive, precise, and accurate for the estimation of MUP and SIM simultaneously in the combined dosage form.

Management of non-healable or maintenance wounds with topical povidone iodine

Although complete healing may appear to be the logical goal for most patients and clinicians, some wounds do not have the potential to heal due to a number of factors such as inadequate vasculature, coexisting medical conditions and medications that prohibit the healing process. Local management of wounds that are considered to have poor potential for healing remains elusive. The purpose of this article is to review the evidence that supports the use of topical antiseptic agents in non-healable wounds. Retrospective chart audit was conducted to evaluate the use of povidone iodine in the management of wounds that were deemed to have poor healing potential.

Use of topical antibiotics as prophylaxis in clean dermatologic procedures

BACKGROUND

Topical antibiotics are not indicated for routine postoperative care in clean dermatologic procedures, but may be widely used.

OBJECTIVE

We sought to describe topical antibiotic use in clean dermatologic surgical procedures in the United States.

METHODS

The 1993 to 2007 National Ambulatory Medical Care Survey database was queried for visits in which clean dermatologic surgery was performed. We analyzed provider specialty, use of topical antibiotics, and associated diagnoses. Use of topical antibiotic over time was analyzed by linear regression.

RESULTS

An estimated 212 million clean dermatologic procedures were performed between 1993 and 2007; topical antibiotics were reported in approximately 10.6 million (5.0%) procedures. Dermatologists were responsible for 63.3% of dermatologic surgery procedures and reported use of topical antibiotic prophylaxis in 8.0 million (6.0%). Dermatologists were more likely to use topical antibiotic prophylaxis than nondermatologists (6.0% vs 3.5%). Use of topical antibiotic prophylaxis decreased over time.

LIMITATIONS

Data were limited to outpatient procedures. The assumption was made that when topical antibiotics were documented at procedure visits they were being used as prophylaxis.

CONCLUSIONS

Topical antibiotics continue to be used as prophylaxis in clean dermatologic procedures, despite being ineffective for this purpose and posing a risk to patients. Although topical antibiotic use is decreasing, prophylactic use should be eliminated.

Topical antibiotic trends from 1993 to 2007: use of topical antibiotics for non-evidence-based indications

BACKGROUND

Systemic antibiotic use has become more conservative with the emergence of drug resistance. Topical antibiotics are employed for a variety of indications, although there are only a few evidence-based indications.

OBJECTIVE

To examine topical antibiotics use in the outpatient setting.

METHODS

Topical antibiotic use was characterized using data from the 1993 to 2007 National Ambulatory Medical Care Survey. Visits were identified at which a topical antibiotic was used and analyzed according to patient demographics, diagnoses, procedures, concomitant medications, and provider specialty. Topical antibiotic use over time was analyzed using linear regression.

RESULTS

The most frequent diagnoses associated with topical antibiotic use were benign or malignant neoplasm of skin, impetigo, insect bite, and cellulitis. Data revealed a significant downward trend in topical antibiotics associated with dermatologic surgery (p<.001) and a nonsignificant downward trend in use in conjunction with skin biopsies (p=.09). Topical antibiotic use by dermatologists was noted to be decreasing over time, whereas among non dermatologists, it was noted to be increasing, although neither of these trends was statistically significant.

CONCLUSION

Topical antibiotics continue to be used for non-evidence-based indications, despite data that suggest that such use may be detrimental for patients and represents significant costs to the health care system. The authors have indicated no significant interest with commercial supporters.

Hyperbranched poly(NIPAM) polymers modified with antibiotics for the reduction of bacterial burden in infected human tissue engineered skin

The escalating global incidence of bacterial infection, particularly in chronic wounds, is a problem that requires significant improvements to existing therapies. We have developed hyperbranched poly(NIPAM) polymers functionalized with the antibiotics Vancomycin and Polymyxin-B that are sensitive to the presence of bacteria in solution. Binding of bacteria to the polymers causes a conformational change, resulting in collapse of the polymers and the formation of insoluble polymer/bacteria complexes. We have applied these novel polymers to our tissue engineered human skin model of a burn wound infected with Pseudomonas aeruginosa and Staphylococcus aureus. When the polymers were removed from the infected skin, either in a polymer gel solution or in the form of hydrogel membranes, they removed bound bacteria, thus reducing the bacterial load in the infected skin model. These bacteria-binding polymers have many potential uses, including coatings for wound dressings.

Combination Povidone-Iodine and Alcohol Formulations More Effective, More Convenient Versus Formulations Containing Either Iodine or Alcohol Alone

Topical antiseptic formulations containing single active ingredients of alcohol and iodine are recognized by the Food and Drug Administration as "generally safe and effective" for "preparation of the skin prior to surgery" or "prior to an injection" including "catheter care, ostomy hygiene, and intravenous site preparation" (Federal Register, 1994). However, a synergistic effect results from the combination of ethyl or isopropyl alcohol and povidone-iodine. Because each active ingredient has different modes of action and performance characteristics, these combination formulations are faster acting with a broader spectrum of antimicrobial activity than formulations containing povidone-iodine alone, and more persistent than formulations containing ethyl or isopropyl alcohol alone.