|Year : 2015 | Volume
| Issue : 4 | Page : 234-242
Development and in vitro characterization of ciprofloxacin loaded polymeric films for wound dressing
Ebere Innocent Okoye, Tobias Azubuike Okolie
Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria
|Date of Web Publication||20-Oct-2015|
Ebere Innocent Okoye
Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Anambra State
Source of Support: None, Conflict of Interest: None
Background and Aim: Wound treatment is always encumbered with diverse challenges, including inadequacy of dressings. This study was undertaken to fabricate and characterize an antibiotic film useable as a wound dressing. Materials and Methods: Gelatin, sodium carboxymethyl cellulose (Na-CMC), and their blends (at 1:1, 1:2, and 2:1) were loaded with ciprofloxacin at drug: polymer ratios of 1:4, 1:6, 1:8, and 1:10 and fabricated into films using the solvent casting method. In vitro characterization of the films was conducted using standard protocols for wound dressing films. Results: The products displayed uniformity of weight and thickness; sorption capacity was 16–24 times their weights of fluid, with significant differences (P < 0.05), blend of polymers conferred much better sorption capability. Their surface pH lied between 6.33 and 6.74; bending endurance was excellent; photomicroscopy revealed uniform distribution of ciprofloxacin crystals; Fourier transform infrared analysis and differential scanning calorimetry showed that ciprofloxacin interactions with infrared and thermal energies were overshadowed by the polymers. The content uniformity of the formulations was within official limits while the in vitro drug release and antibacterial activities revealed that polymer blends at 1:1 or 1:2 (Na-CMC: gelatin) stood out as the most promising combination for the formulation of ciprofloxacin wound dressing films. Conclusion: Combination of Na-CMC and gelatin in the fabrication of wound dressing film is an attractive choice judging from the outcome of this study. The antibacterial activities and sorption capacities of the drug loaded films are strong indicators to their in vivo functionalities as wound dressing.
Keywords: Ciprofloxacin, gelatin, sodium carboxymethyl cellulose, wound dressing
|How to cite this article:|
Okoye EI, Okolie TA. Development and in vitro characterization of ciprofloxacin loaded polymeric films for wound dressing. Int J Health Allied Sci 2015;4:234-42
|How to cite this URL:|
Okoye EI, Okolie TA. Development and in vitro characterization of ciprofloxacin loaded polymeric films for wound dressing. Int J Health Allied Sci [serial online] 2015 [cited 2020 Jul 10];4:234-42. Available from: http://www.ijhas.in/text.asp?2015/4/4/234/167660
| Introduction|| |
In the hustle and bustle lifestyles that characterize human and veterinary societies wounds are indisputably daily prices. Wounds are injuries that break the skin or other body tissues. They include cuts, scrapes, scratches, and punctured skin. They often happen because of an accident, but surgery, sutures, and stitches also give rise to wounds, which with respect to the healing process, can be classified as acute or chronic wounds. Acute wounds are caused by traumas, but the wounds are usually healable within 8–12 weeks. On the other hand, chronic wounds are those injuries which are produced as a result of specific diseases such as diabetes, tumors, venous stasis, peripheral vascular diseases, pressure ulcerations, and other severe physiological imbalances; and healing of these wounds could take more than 12 weeks , with recurrence not uncommon. An open wound is a favorable niche for microbial colonization and infection; and major infecting organisms include: Streptococcuspyogenes,Enterococcusfaecalis,Staphylococcus aureus,Pseudomonasaeruginosa,Enterobacter species, Escherichiacoli,Klebsiella species, Proteus species, Bacteroides, Clostridium species, Yeasts (Candida) and Aspergillus. But the most commonly infecting organisms are: S.aureus,P.aeruginosa and S.pyogenes. Whereas minor wounds may heal easily or worsen into open sores that may become infected, major wounds usually become infected especially when carelessly handled.
With the increasing incidence of diabetes and other debilitating diseases, chronic wounds which are one of their complications are becoming serious public health issues. Handling of such wounds among other factors is, therefore, critical to their healing processes. Wound dressings are indispensible in the treatment of chronic wounds. And because chronic wounds are often infected, dressings impregnated with antimicrobial agents have become the mainstay of wound treatment. It has been reported that semi-permeable dressings enhance the healing process in acute and chronic wounds by keeping healing tissues moist and increasing superficial wound epithelialization., The permeability to water is also important so that fluid from the wound does not build up between the wound and the dressing and that wound desiccation does not occur.
Many biomaterials (e.g., chitosan, alginates, gelatin, celluloses, etc.,), all of which interact with aqueous medium to form hydrogels, have been used in fabricating wound dressing. Sodium carboxymethyl cellulose (CMC) is a semisynthetic derivative of cellulose produced by the hydration of pulp (cellulose) with sodium hydroxide, an alkaline reaction catalyzed with chloroacetic acid. The presence of sodium in CMC confers polyelectrolyte nature to it, and this makes it an excellent biomaterial for the development of superabsorbent hydrogels with a smart behavior. It has been reported to protect wounds from extraneous matters; has a strong ability to absorb and transport fluids, thereby enhancing the rate of healing, and may be involved in the repair of the ocular surface. Gelatin is a heterogeneous mixture of high molecular weight polypeptides derived from partial acid (α-type) or basic (β-type) hydrolysis of natural collagens (proteins) found in animal skin, tendon, cartilage, and bone. It is a biodegradable, biocompatible, and nonimmunogenic biomaterial, hence its wide applications in the food, pharmaceutical, and medical industries. Gelatin easily forms films, but its solubility in water, which is at temperatures >35°C and the poor mechanical strength of its films limit its use as a structural biomaterial., Wound dressing, containing gelatin as one of the excipients, has been reported to enhance wound healing.,
Ciprofloxacin is a second generation fluoroquinolone antibiotic useful for the treatment of diverse bacterial infections including those caused by Gram-positive and Gram-negative bacteria., Among ciprofloxacin's many indications is its application in the treatment of skin and skin structure infections caused by E. coli,Klebsiellapneumoniae,Enterobactercloacae,Proteusmirabilis,Proteusvulgaris,Providenciastuartii,Morganellamorganii,Citrobacterfreundii,P.aeruginosa, methicillin-susceptible S.aureus, methicillin-susceptible Staphylococcusepidermidis, or S.pyogenes., It is one of the most widely used antibiotics in wound healing because of its low minimal inhibitory concentration for both Gram-positive and Gram-negative bacteria that cause wound infections and the frequency of spontaneous resistance to ciprofloxacin is very low. This work was therefore aimed at developing a ciprofloxacin loaded wound dressing material fabricated from gelatin and sodium carboxymethyl cellulose (Na-CMC) and conducting in vitro assessment of its properties as pointers to its usability in wound dressing.
| Materials and Methods|| |
Ciprofloxacin hydrochloride was a gift from Juhel Pharmaceuticals Ltd., Nigeria, absolute ethanol (Sigma Aldrich, Germany), Na-CMC (Fluka, Netherlands), gelatin (gel strength: 160 Bloom) (Fluka Germany), glycerine (Sigma-Aldrich, Germany), phosphate buffer pH 6.8 tablets (Thermo Fisher Scientific, USA), distilled water, Mueller-Hinton agar, and broth (Oxoid, Basingstoke, UK), pure strains of S.aureus and P.aeruginosa cultures were respectively obtained from the Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Nigeria, and Department of Pharmaceutics and Pharmaceutical Microbiology, Faculty of Pharmacy, Madonna University, Elele, Nigeria. Water was double distilled and other reagents were of analytical grade.
Preparation of drug loaded films
The ciprofloxacin was loaded into gelatin (GEL) films, Na-CMC films, as well as films formulated with mixtures of the two polymers at different ratios. The polymers were mixed at ratios of 1:1, 1:2, and 2:1 (GEL: Na-CMC). In order to prepare the drug loaded films, drug: polymer ratios employed were 1:4, 1:6, 1:8, and 1:10 [Table 1]. Solvent casting method which has been reported to yield very high-quality films  was used in the preparation of the wound dressing films. Five hundred milligrams of ciprofloxacin were dissolved in 5 ml of ethanol: water (60:40) solution. The relevant amount of polymer(s) [Table 1] was dissolved in 10 ml of distilled water at 40°C using a magnetic stirrer (P Selecta Agimatic E-C, Barcelona) at 100 rpm. Glycerine 30% w/w (with respect to polymer) was added, and the three mixtures were mixed at 100 rpm for 5 min, before the volume was made up to 30 ml with distilled water and stirring at 100 rpm was continued for 30 min. The mixture was then allowed to stand at room temperature (32°C) for 10 min, poured into a petri dish and allowed to dry inside a closed chamber at 32°C for 72 h. Thereafter, the films were carefully removed from the petri dishes, sectioned into 1 cm by 2 cm dimensions and stored in airtight glass containers.
Determination of uniformity of weight and thickness of the films
Five films selected randomly from each batch were weighed individually using an electronic balance (Mettler Toledo B154, Switzerland); while their thicknesses were measured at four different points using Mitutoyo micrometer gauge (Model 10C – 1012 EB Japan) and the results presented as mean ± standard deviation.
Determination of bending endurance of films
This was conducted in triplicate by hand bending a film (2 cm × 1 cm) selected at random from each batch along its width repeatedly at the same place until it breaks or is bent 300 times. The number of times the film could be bent at the same place without breaking was taken as its bending endurance.
Determination of sorption capacity of films
Each selected film was initially weighed (Wi) before it was placed in a petri dish containing 10 ml of phosphate buffer of pH 6.8 and the assembly was placed inside an empty desiccator. After 24 h, the film was reweighed (Wf), and the sorption capacity was evaluated using equation 1. Triplicate determinations were done for each batch.
Determination of surface pH of films
The surface pH of films was determined by allowing each selected film to hydrate in 10 ml of distilled water in a petri dish for 2 h at 37°C ± 1°C and then measuring the surface pH by placing the electrode of a pH meter (Corning, model 10 England) at the surface of the hydrated film.
Differential scanning calorimetry
This was conducted with the calorimeter-Netzsch differential scanning calorimetry 204 FI (Phoenix, Germany). Four milligrams of each sample (ciprofloxacin, polymer or formulation) were carefully weighed and sealed in aluminum pan with a similar empty pan serving as a control. The machine was calibrated with indium and purged with nitrogen gas. Heating of the sample was carried out at the rate of 10°C/min from 30°C to 400°C under nitrogen flow rate of 20 ml/min followed by cooling back to 30°C at the same rate.
Fourier transform infrared analysis
The Fourier transform infrared analysis (FTIR) was conducted using the apparatus FTIR 8400S spectrophotometer (Shimadzu, Japan). Two milligrams of each sample (ciprofloxacin, polymer or formulation) and 200 mg KBr were powdered using an agate mortar and pestle and compressed with a pellet press. The resulting pellet was mounted on the sample holder, and the system was purged with nitrogen gas. Scanning was carried out in the range of 400–4000 cm 1 with a resolution of 1 cm 1.
Photomicroscopy of the films
This was conducted using the Nikon Eclipse light microscope (model ME 600, Nikon, Melville, NY, USA) fitted with Link system software. Each film was placed on the microscope stage and observed by focusing with ×40 lens. The image was finely focused and captured on the computer LCD screen. Duplicate images were saved for each film, and the clearer one selected.
Determination of ciprofloxacin content and content uniformity in polymer films
This was conducted using phosphate buffer pH 6.8 and methanol. Three films were selected at random from each batch, and one film was crushed each time using mortar and pestle in the presence of 15 ml phosphate buffer. The mixture was transferred to a 50 ml volumetric flask and made up to volume with methanol. The resulting mixture was then shaken for 2 h using a shaker (digital orbital and reciprocal shaker, KS/HS 501, Thomas Scientific, USA) and filtered through Whatman no 1 filter paper. The content of drug was estimated by measuring the absorbance of the filtrate spectrophotometrically at 277 nm (UV – 160A Shimadzu Corporation, Japan) using the filtrate obtained from similarly treated drug-empty polymer film as blank and applying the calibration curve regression equation: Y = 0.1052x + 1.0063; r² = 0.9942. The uniformity of contents of the various batches was investigated by computing their relative standard deviation and converting their contents of ciprofloxacin to percentage.
In vitro drug release study
The apparatus used was a 100 ml beaker and the medium was phosphate buffer pH 6.8. Fifty milliliters of the medium were used for each film sample, and the magnetic stirrer supplied the needed agitation at 50 rpm and a temperature of 37°C ± 2°C. The study was carried out for 3 h and in the first 30 min, 5 ml of dissolution fluid was withdrawn at 5 min intervals, with 5 ml fresh medium used to replace the withdrawn sample each time. Thereafter, withdrawals were done at 30 min intervals up to 3 h. Each withdrawn sample was filtered, diluted 10-fold wise and its absorbance determined spectrophotometrically at 277 nm, using the filtrate obtained from similarly treated drug-empty polymer film as blank and applying the calibration curve regression equation: Y = 0.1052x + 1.0063; r² = 0.9942. Triplicate determinations were made for each batch selected.
In vitro antibacterial activity of the films
This was conducted by agar diffusion method using pure strains of S.aureus and P.aeruginosa, which were maintained on Mueller-Hinton agar and broth (Oxoid, Basingstoke, UK). Investigations were performed initially to ensure that bacterial growth could be sustained using Mueller-Hinton broth and comparing colony counts (cfu/ml) following incubation at 37°C for 24 h. Circular petri dishes containing a 5 mm layer of Mueller-Hinton agar were inoculated with 1 ml of a 1 × 106 cfu/ml broth culture of each test organism. The suspension was distributed uniformly over the surface of the plate and allowed to dry. Then the films (1 cm 2) were placed at the center of the plates and were incubated for 24 h at 37°C. The inhibition zone diameters (IZDs) surrounding the tested films were then measured. Triplicate determinations were made for each batch of films. Films containing no drug were used as control in the study.
Graphing and regression analyses were performed with Graphpad Prism 5 (GraphPad Prism software Inc., 2012 San Diego, California, USA) while analysis of the results of various parameters tested was performed using one-way analysis of variance in Excel statistical package 2007. Significant differences were defined by P < 0.05.
| Results|| |
The mean weight of the wound dressing films ranged from 0.11 ± 0.02 g (F0) to 0.71 ± 0.01 g (F20), with corresponding thickness of 0.66 ± 0.02 mm (F0) and 4.02 ± 0.02 mm (F20) as shown in [Table 2]. For both parameters, the differences in the values of each batch of film formulations were significantly low as tested using standard deviation, which lied between 0.01 and 0.02. All the batches exhibited extensively high bending endurance in that none cracked, broke, or showed any sign of fracture during the 300 times bending experiment. This is indicative of the high flexibility of the films which is a desirable quality for wound dressings.
The wound dressing films sorbed between 16 and 24 times their weights of buffer, except films fabricated with gelatin alone which dispersed completely in the medium within the period of the test [Table 2]. The presence of Na-CMC conferred a better sorption capacity on the films as can be seen from the results as shown in [Table 2]. It can also however be observed that films formulated with Na-CMC alone sorbed significantly lower (P < 0.05) amount of fluid than films formulated with blends of gelatin and Na-CMC. Within the 2:1 (Na-CMC: gelatin) group, statistical analysis revealed no significant difference in the sorption capacity between wound dressings fabricated at 1:8 and 1:10 (drug: polymer) ratios.
[Table 2] also shows the values of surface pH of the films, which were of the order: 6.31 ± 0.02 (F16) to 6.74 ± 0.06 (F6). The surface pH values of films containing more Na-CMC were significantly different (P < 0.05) from those of films containing more gelatin. Films formulated with gelatin alone possessed surface pH values that were significantly lower (P < 0.05) than those of the other films.
The FTIR spectra of ciprofloxacin and one of the wound dressing films are shown in [Figure 1]. Some of the peaks from the drug were no longer visible in the spectrum of the formulation, and this might have resulted from some functional groups which were present in both drug and excipients appearing at one peak, or that the excipients "drowned" the small amount of drug molecules interacting with the infrared energy thereby prevented them from being noticed in the spectrum.
|Figure 1: Fourier transform infrared analysis spectra of ciprofloxacin (a) and wound dressing F4: Formulated with 0.5 g drug, 2.5 g gelatin, and 2.5 g sodium carboxymethyl cellulose (b)|
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The thermogram for pure ciprofloxacin [Figure 2]a shows two endothermic events: The dehydration temperature, which peaked at 152.1°C; and the melting point which peaked at 324.3°C. [Figure 2]b shows the superimposition of the thermograms of various formulations of the wound dressing which revealed the masking of the pure drug by the polymers.
|Figure 2: DSC thermogram of ciprofloxacin (a) and superimposed thermograms of pure ciprofloxacin; F20: formulated with 0.5 g drug and 5.0 g Na-CMC; F4: formulated with 0.5 g drug, 2.5 g gelatin and 2.5 g Na-CMC; F12: formulated with 0.5 g drug, 3.33 g gelatin and 1.67 g Na-CMC; F8: formulated with 0.5 g drug, 1.67 g gelatin and 3.33 g Na-CMC; and F16: formulated with 0.5 g drug and 5.0 g gelatin(b)|
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The photomicrographs of some of the formulations are displayed in [Figure 3]. From the photomicrographs, it can be seen that the distribution of the crystals of the drug is more uniform in films formulated with blends of Na-CMC: gelatin at 1:1 or 1:2 combination ratios (F2, F4, F10 and F12). At 2:1 ratio of Na-CMC: gelatin, the dispersion is also good but was not very visible under the microscope because of the thickness of the film (F8). Where single polymers were used, the drug crystallized as large clumps (F15-gelatin alone) or much bigger crystals (F17-lowest concentration of Na-CMC alone). At the highest concentration of Na-CMC used alone (1:10 of drug: polymer), the drug crystals were barely visible because of the thickness of the film (≥4 mm). These results highlight the fact that blending the polymers gave films with much better physicopharmaceutical properties.
|Figure 3: Photomicrograph of some of the formulated wound dressings.F2: Formulated with 0.5 g drug, 1.5 g gelatin, and 1.5 g sodium carboxymethyl cellulose; F4: Formulated with 0.5 g drug, 2.5 g gelatin, and 2.5. g sodium carboxymethyl cellulose; F8: Formulated with 0.5 g drug, 1.67 g gelatin, and 3.33 g sodium carboxymethyl cellulose F10: Formulated with 0.5 g drug, 2.0 g gelatin, and 1.0 g sodium carboxymethyl cellulose; F11: Formulated with 0.5 g drug, 2.67. g gelatin, and 1.33 g sodium carboxymethyl cellulose; F12: Formulated with 0.5 g drug, 3.33 g gelatin, and 1.67 g sodium carboxymethyl cellulose; F15: Formulated with 0.5 g drug and 4.0 g gelatin; F17: Formulated with 0.5 g drug and 2.0 g sodium carboxymethyl cellulose; F20: Formulated with 0.5 g drug and 5.0 g sodium carboxymethyl cellulose|
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The contents of ciprofloxacin in the various wound dressing films are presented in [Table 2]. The contents range from 22.55 ± 0.02 mg (F13) to 25.19 ± 0.04 mg (F12). A close look at the values reveals that there was no particular relationship between the polymer type or concentration and the amount of drug contained in the films. At a glance, it appears as though the contents differ, but when the entire formulations were subjected to statistical analysis, no significant difference was revealed in their contents.
The drug release profiles of some selected formulations are shown in [Figure 4]. Formulation F14 and F15 displayed high burst effect, attained peak release at 30 min and maintained the drug concentration over 2.5 h. These two formulations contain only gelatin as the film forming polymer; and its dissolution at 37°C explains the burst effect, while the drug crystals dissolution accounts for the maintenance of the release profile over the 2.5 h. A low burst effect was witnessed in the formulations that contained a blend of the two polymers or Na-CMC alone; while the lowest burst effect as well as profile was observed in films formulated with the two polymers at 1:1 ratio (F2 and F3). Apart from films formulated with gelatin alone, no other formulation released its entire content of drug in 3.0 h. Films formulated with Na-CMC alone released <60% of their drug content in 3.0 h, while those formulated with the blend of the two polymers at 1:1 ratio released <40% within the same period.
|Figure 4: In vitro dissolution profiles of the wound dressings.F2: Formulated with 0.5 g drug, 1.5 g gelatin, and 1.5 g sodium carboxymethyl cellulose; F3: Formulated with 0.5 g drug, 2.0 g gelatin, and 2.0 g sodium carboxymethyl cellulose; F6: Formulated with 0.5 g drug, 1.0 g gelatin, and 2.0 g sodium carboxymethyl cellulose; F7: Formulated with 0.5 g drug, 1.33 g gelatin, and 2.67 g sodium carboxymethyl cellulose; F10: Formulated with 0.5 g drug, 2.0 g gelatin, and 1.0 g sodium carboxymethyl cellulose; F11: Formulated with 0.5 g drug, 2.67 g gelatin, and 1.33 g sodium carboxymethyl cellulose; F14: Formulated with 0.5 g drug and 3.0 g gelatin; F15: Formulated with 0.5 g drug and 4.0 g gelatin; F18: Formulated with 0.5 g drug and 3.0 g sodium carboxymethyl cellulose; F19: formulated with 0.5. g drug and 4.0. g sodium carboxymethyl cellulose|
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The in vitro antibacterial activities of the films are shown in [Figure 5]. The loaded films showed more activity against S.aureus in comparison to P. aeruginosa [Figure 5]. Formulation F13 produced the highest IZD on both organisms. This film was fabricated with gelatin at drug: polymer ratio of 1:4. It is therefore not contrary that its IZD was the highest. The contrast is this films deficiency in sorption of phosphate buffer, thereby negating its utility as a wound dressing film. Films formulated with polymer blend at 1:1 ratio produced higher IZD than those fabricated with Na-CMC: gelatin at 2:1 ratio. Also, with Na-CMC: gelatin 1:2 ratio, the IZD was higher than at 1:1 ratio. The observations in S. aureus are to some extent contrasted in P. aeruginosa. Here, films formulated with 1:1 polymer blend produced lower IZDs than 2:1 or 1:2 (Na-CMC: gelatin).
|Figure 5: In vitro antibacterial activities of the wound dressings against Staphylococcus aureus and Pseudomonas aeruginosa as measured using inhibition zone diameter-F0: Formulated with 0.0 g drug, 1.0 g gelatin, and 1.0 g sodium carboxymethyl cellulose; F1: Formulated with 0.5 g drug, 1.0 g gelatin, and 1.0 g sodium carboxymethyl cellulose; F2: Formulated with 0.5 g drug, 1.5 g gelatin, and 1.5 g sodium carboxymethyl cellulose; F3: Formulated with 0.5 g drug, 2.0 g gelatin, and 2.0 g sodium carboxymethyl cellulose; F4: Formulated with 0.5 g drug, 2.5 g gelatin, and 2.5 g sodium carboxymethyl cellulose; F5: Formulated with 0.5 g drug, 0.67 g gelatin, and 1.33 g sodium carboxymethyl cellulose; F6: Formulated with 0.5 g drug, 1.0 g gelatin, and 2.0 g sodium carboxymethyl cellulose; F7: Formulated with 0.5 g drug, 1.33 g gelatin, and 2.67 g sodium carboxymethyl cellulose; F8: Formulated with 0.5 g drug, 1.67 g gelatin, and 3.33 g sodium carboxymethyl cellulose; F9: Formulated with 0.5 g drug, 1.33 g gelatin, and 0.67 g sodium carboxymethyl cellulose; F10: Formulated with 0.5 g drug, 2.0 g gelatin, and 1.0 g sodium carboxymethyl cellulose; F11: Formulated with 0.5 g drug, 2.67 g gelatin, and 1.33 g sodium carboxymethyl cellulose; F12: Formulated with 0.5 g drug, 3.33 g gelatin, and 1.67 g sodium carboxymethyl cellulose; F13: Formulated with 0.5 g drug and 2.0 g gelatin; F14: Formulated with 0.5 g drug and 3.0 g gelatin; F15: Formulated with 0.5 g drug and 4.0 g gelatin; F16: Formulated with 0.5 g drug and 5.0 g gelatin; F17: Formulated with 0.5 g drug and 2.0 g sodium carboxymethyl cellulose; F18: Formulated with 0.5 g drug and 3.0 g sodium carboxymethyl cellulose; F19: Formulated with 0.5 g drug and 4.0 g sodium carboxymethyl cellulose; F20: Formulated with 0.5 g drug and 5.0 g sodium carboxymethyl cellulose|
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| Discussion|| |
The mean weights of the wound dressings increased with polymer ratio in the film, and so were the corresponding mean thickness values. This is in order and also highlights the homogeneous spreadability of the gels when poured into the petri dishes during the formulation of the films.
The sorption capacity of wound dressings may be related to their ability to soak exudates from wound surfaces while maintaining the moist environment necessary for the healing process to take place., Since formulations containing blends of the two polymers displayed significantly higher (P < 0.05) sorption capability than those formulated with single polymers, this result seems to suggest that there might have been some physical interaction between the polymers during the formulation process, which gave rise to a hydrogel with higher sorption capacity in comparison to any of the individual polymers. The highest sorption capacities were observed in films formulated with Na-CMC: gelatin blend at 2:1 ratios (F5 – F8). These results are similar to a previous report on hyaluronic acid and Na-CMC.
The pH values are slightly acidic conditions which are advantageous for wound dressings because such environments have been shown to enhance wound healing., The surface pH values of films containing more Na-CMC were significantly different (P < 0.05) from those of films containing more gelatin. Films formulated with gelatin alone possessed surface pH values that were significantly lower (P < 0.05) than those of the other films. This suggests that gelatin is acting as an acid in this circumstance since it is amphoteric in nature.
In the FTIR spectra, the peaks visible in ciprofloxacin [Figure 1]a include those at frequencies of 583.49 cm 1 which may be ascribed to C-C-C bending vibrations, 1044.49 cm 1 (C-F stretching vibration), 1347.32 cm 1 (aromatic C-H in-plane bend), 1433.16 cm 1 (C = C-aromatic ring stretching vibration, 1642.44 cm 1 (C-H stretching vibration of quinoline group), 2895.25 cm 1 (C-H symmetric stretch), and 3413.15 cm 1 (N-H stretching of aromatic amine group).,,, The spectrum for formulation F4 [Figure 1]b revealed peaks that were contributed by Na-CMC, gelatin, and ciprofloxacin. The peak at 3415 cm 1 may be ascribed to the N-H stretching of aromatic amine group in ciprofloxacin while the 3266 cm 1 might be from N-H stretching of amide A moiety of gelatin. The broad and intense peaks at 3007–3142 cm 1 may be assigned to -OH stretching of the hydroxyl groups in Na-CMC. The peaks at 2814 cm 1 and 2516–2660 cm 1 may be from the C-H symmetric stretching in Na-CMC or the drug and S-H stretching vibrations in gelatin respectively. The peaks that lie between 1368 and 1800 cm 1 are likely due to C-N stretch and N-H in-plane deformation vibrations from peptide groups in amide II and amide II moieties of gelatin.,,,,, Some of the peaks from the drug were no longer visible in the spectrum of the formulation, and this might have resulted from some functional groups which were present in both drug and excipients appearing at one peak, or that the excipients 'drowned' the small amount of drug molecules interacting with the infrared energy thereby prevented them from being noticed in the spectrum.
The values of the endothermic parameters in the thermogram of pure ciprofloxacin are similar to the ones reported by previous workers. In the thermograms of the various formulations, the presence of ciprofloxacin was not revealed, and this could be attributed to the entrapment of the drug in the matrices of the polymer. This result is evident in [Figure 2]b, where the superimposition of the thermograms of various formulations of the wound dressing showed the masking of that of the pure drug, a finding that is similar to previous report.
The content of ciprofloxacin in all the batches met the pharmacopeial requirements for content uniformity since none of them has relative standard deviation > ±5% and their actual ciprofloxacin contents lied between 90% and 101% of the theoretical contents. This may be tied to the homogeneity of the spreading and dispersion of drug during formulation.
The in vitro drug release profiles of the wound dressings were inversely affected by the drug: polymer ratio as polymer concentration was increased, a finding that is in agreement with previous reports., The differences in release profiles may be accounted for by differences in the matrix forming abilities of the polymers. Na-CMC forms strong/less permeable matrix than gelatin, and this may explain the observed profiles. On the other hand, the 1:1 ratio seems to be most favorable for the formulation of hydrogel with least permeability characteristics to the drug, hence lowest profile displayed by films fabricated with it. These observations are positively related to previous findings on drug release from polymeric films.
The in vitro antibacterial activity of the blank film may be attributed to gelatin in accordance with previous reports. When the results of antibacterial activities of the wound dressings are related to the in vitro drug release profile [Figure 4], a corroborative evidence is apparent. The link lies in the fact that albeit the 1:1 polymer ratio yielded the lowest drug release profile, its content of drug may be available for a period longer than 3 h. This suggests that beyond this time, it may still be releasing active drug which continues to kill the bacteria, thus the increase in IZD. The possible explanation for the observed higher IZDs on plates containing S. aureus is that the P. aeruginosa used was more resistant than the S. aureus. In that case, the slower drug release rate of 1:1 films enabled the bacterial cells to activate their resistance armoury against the drug. This trend was observed in films with slow release rates (F11, F18, and F19). The activities of ciprofloxacin to S.aureus and P.aeruginosa in this work are however contrary to reports published previously by other researchers in Nigeria.,
| Conclusion|| |
Gelatin, Na-CMC, and their blends were successfully fabricated as wound dressing films loaded with ciprofloxacin. The films formulated with blends of the two polymers displayed significantly better physicopharmaceutical properties than those fabricated with any of the polymers alone. Among the films fabricated with polymer blends, the best functionality (taking all qualities tested into consideration) was identified in films fabricated with gelatin: Na-CMC at 1:1 ratio. It can thus be concluded that formulating wound dressing films with a combination of polymers may be a better option than using a monopolymer. In addition, the wound dressing in this research is better than other dosage forms for wound dressing, e.g., ointment, creams, gels, etc., because these dosage forms do not adsorb exudates from wounds, largely possess slightly basic pH that does not enhance wound healing and are oily (except gels) hence delay wound healing.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]