INTRODUCTION:

Ciprofloxacin, a fluoroquinolone antibiotic with a broad spectrum of activity, is commonly prescribed for the treatment of bacterial infections like pneumonia and urinary tract infections. Despite its effectiveness, ciprofloxacin suffers from poor solubility in water and limited bioavailability when taken orally¹. Classified under the Biopharmaceutics Classification System (BCS) as a class IV drug, it is characterized by both low solubility (0.067mg/mL at 25°C, pH 7.5^2,3) and low permeability. Various strategies have been explored to enhance the solubility of such poorly soluble drugs, including reducing particle size, creating nanosuspensions, employing surfactants, forming salts, adjusting pH, and developing solid dispersions⁴.

Lipid-based drug delivery systems offer an alternative strategy for improving the solubility of poorly soluble drugs, facilitating targeted and controlled release for both small and large molecules^5,6. These systems are categorized into four types: I, II, III, and IV⁷. Specifically, Type III systems, known as self-emulsifying drug delivery systems (SEDDS), consist of isotropic mixtures that may include natural or synthetic oils, surfactants (either solid or liquid), and hydrophilic solvents or co-solvents^8,9. Upon exposure to mild agitation and subsequent dilution in aqueous environments like gastrointestinal fluids, SEDDS spontaneously form fine oil-in-water emulsions or microemulsions. The term SEDDS broadly refers to systems that produce emulsions with droplet sizes ranging from 100 to 250nm in the case of SMEDDS, and less than 100nm for SNEDDS^10,11. Unlike traditional emulsions, which are thermodynamically unstable, SEDDS are physically stable and relatively easy to manufacture. For lipophilic drugs with limited absorption, these systems can significantly improve both the rate and extent of absorption, resulting in more predictable blood concentration profiles over time.

The aim of this work would be to is to develop and characterize a novel Self-Microemulsifying Drug Delivery System (SMEDDS) for ciprofloxacin, with the aim of enhancing its solubility.

MATERIALS AND METHODS:

1) Materials:

Ciprofloxacin, as a model drug, was donated by the pharmaceutical company Pharma5 (Morocco). Lipophilic labrafac® WL 1349 (propylene glycol dicaprylocaprate) were received as a gift from Gattefosse (SAS, France). Tween® 20 (polyoxyethylenesorbitan monolaurate), tween® 40 (polyoxyethylenesorbitanmonopalmitate), tween® 80 (polyoxyethylenesorbitan monooleate), polyethylene glycol with an average molecular weight of 400 (PEG 400), propylene glycol (PG), cottonseed oil, methanol and 1-butanol were purchased from Sigma-Aldrich GmbH (Germany). Oleic acid was obtained from FlukaChemie AG (Switzerland). Certified high-purity Moroccan argan oil (Argania spinosa L.) and olive oil were sourced from SOMAPROL (Morocco). Ethanol (96% w/w) was purchased from Prolabo (France). Freshly distilled and filtered water was used throughout the study.

2) Solubility studies:

The solubility of ciprofloxacin in different oils, surfactants, and co-surfactants was assessed by introducing an excess of the drug into vials containing 2 ml of each vehicle. These mixtures were thoroughly blended using a vortex mixer to enhance solubilization. The samples were then placed in a shaking bath at a controlled temperature of 25±2°C for 48hours to reach equilibrium. Following this, the mixtures were centrifuged at 3,000rpm for 10 minutes. A 0.1ml aliquot of the supernatant was collected, and the drug concentration was determined using a SHIMADZU UV-1280 Spectrophotometer after appropriate dilution with methanol. The absorbance was recorded at a wavelength of 335nm¹². The method used was validated and demonstrated to be reliable, accurate, and reproducible, consistently yielding dependable results.

3) Pseudo-ternary diagram:

Following solubility studies, specific TA and co-TA were selected to construct a pseudoternary phase diagram. To map out the microemulsion region, we employed the water titration method at 37°C to create these diagrams. Different volumetric ratios of TA and co-TA (Smix) were prepared, including 3:1, 2:1, 1:1, 1:2, and 1:3 proportions. Each Smix ratio was then combined with oil in varying proportions (1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1), with the total volume maintained at 1mL. The mixtures were stirred at 75rpm using a magnetic stirrer and titrated with water, added drop by drop, until the total volume reached 100mL (resulting in a 1:100 dilution). After each water addition, the emulsion was visually assessed for signs of turbidity or clarity.

4) Preparation of SMEDDS:

Based on the pseudo-ternary phase diagram, formulations were designed using oil, surfactant, and co-surfactant concentrations that correspond to the microemulsion regions (refer to the diagram). To begin, the oil phase was measured into a vial, and 250mg of the drug was directly added and mixed using a vortex mixer. The appropriate amount of Smix was subsequently incorporated into the oil-drug mixture, followed by additional vortex mixing and homogenization for 10 minutes. A total of six different formulations were prepared, as detailed in Table I.

Table I: Ciprofloxacin-based SMEDDS formulations

Formulation code

Argan Oil (%)

Labrafac (%)

PEG 200 (%)

F2
F3
F4
F5
F6

5) Thermodynamic studies:

Thermodynamic stability and phase separation studies were conducted to evaluate the resilience of the SMEDDS formulations under challenging conditions. The formulations were centrifuged at 6,000rpm for 15 minutes. Additionally, the selected formulations underwent three freeze-thaw cycles, where they were exposed to temperatures of 40°C, room temperature, and -20°C, respectively. Each formulation was maintained at these temperatures for 48 hours to assess stability.

6) Emulsification time:

The self-emulsification time was determined using a USP dissolution apparatus II. Each vessel was filled with 500ml of distilled water, stirred at a speed of 50 rpm, and maintained at a constant temperature of 37± 2°C. A 100µL sample of the SEDDS formulation was introduced into the apparatus, and the time required for the emulsion to form was recorded as the self-emulsification time. Visual assessments were also conducted to evaluate the self-emulsification process, focusing on dispersibility, ease of emulsification, and the final appearance of the emulsion, using a grading system as outlined in Table II¹³.

Table II: Visual Assessment of Efficiency of Self-Microemulsification

Dispersability and Appearance

Time of Self-Emulsification (min)

Grade

Formulation spreads rapidly in water forming clear and transparent microemulsion

Formulation formed transparent, gel like intermediate structure prior to dispersing completely but could form microemulsion

Formulation droplets spread in water to form turbid emulsion

Formulation exhibits poor emulsification with coalescence of oil droplets

3–5

7) Droplet size and zeta potential analysis:

Formulations were diluted up to 100-fold with distilled water (dilution factor 100), and the droplet size, polydispersity index and zeta potential of each formulation were determined (ZS90, Malvern Instrument).

RESULTS AND DISCUSSION:

1) Solubility studies:

Solubility plays an important role in the formulation of SMEDDS. The loading capacity of this formulation is directly influenced by the solubility of the active ingredient in oil, surfactant, co-surfactant¹⁴. The results made it possible to select the 3 components of the formulation with the greatest solubility among the excipients; argan oil as an oil, Labrafac as a surfactant and PEG 200 as a co-surfactant (Table III). Argan oil, although its use is rare in medicines, has been widely used in traditional medicine for hundreds of years. It is incorporated into pharmaceutical and cosmetic preparations¹⁵.

Table III: Solubility of ciprofloxacin in oils; surfactants and co-surfactants.

Components

Solubility (mg/l)

Oils

Olive Oil

Argan Oil

Soj Oil

Oleic Acid

0.24

1.88

0.52

1.67

Surfactants

Labrafac

Tween 20

Tween 60

Tween 80

0.38

0.15

0.1

0.31

Cosurfactants

Propylen glycol

PEG 200

PEG 400

1,699

1,724

1,552

2) Pseudo ternary diagram and thermodynamic studies:

The pseudoternary phase diagram is employed to identify the optimal combination of oil, surfactant, and co-surfactant concentrations necessary to form the microemulsion. Figure 1 displays the pseudoternary phase diagrams developed for Argan oil (oil), Labrafac (surfactant), and PEG 200 (co-surfactant). Each component is represented at 100% at the apex of the diagram. The stable formulation region corresponding to SMEDDS is highlighted in grey. Based on the results from the pseudoternary diagram, formulations exhibiting SMEDDS properties were prepared within the grey-marked region. These formulations included Argan Oil (1%-10%), Labrafac (50%-90%), and PEG 200 (1%-40%), with the amount of ciprofloxacin kept constant (Table II).

Figure 1: Phase diagrams of Argan oil/Labrafac/PEG 200 system indicating microemulsion existence region

No phase separation or drug precipitation was observed in the F1-F6 formulations. During the study, no significant changes were observed in the stability of ciprofloxacin SMEDDS in response to temperature variation. Despite the fact that in SMEDDS, microemulsions are strongly affected by temperature changes and/or dilutions and are even fragmented by these alterations¹⁶. This finding could be attributed to the robustness of the formulation or to the specific nature of the components used. It is also possible that the experimental conditions we used were not extreme enough to trigger significant alterations in the microemulsion.

3) Emulsification time:

Emulsification studies will be carried out to evaluate the self-emulsifying characteristics of the selected formulations. SMEDDS are expected to disperse rapidly and completely when subjected to aqueous dilution and gentle agitation. The results indicated that emulsification time decreases as the proportion of surfactant increases (Table IV). This effect is likely due to water penetrating the oil/water interface, where the swelling caused by the formation of liquid crystals aids in the emulsification process^17-19.

Table IV: Emulsification time of different batches of prepared SMEDDS.

Batch code

Emulsification time (seconds)

F2
F3
F4
F5
F6

4) Droplet size and zeta potential analysis:

In SEDDS formulations, droplet size and zeta potential are critical factors that significantly influence the drug's in vivo performance. Ideally, droplet sizes should range between 100 and 500nm²⁰, with SEDDS typically producing droplets between 100nm and 250nm, as previously noted. The polydispersity index (PDI) indicates the distribution of droplet sizes, where a low PDI reflects a narrow size range, which is desirable for SEDDS formulations. Zeta potential, which measures the charge of the droplets, determines the degree of electrostatic repulsion among particles in a dispersion. A high zeta potential, generally above ±30mV, is indicative of a stable dispersion²¹, as it helps prevent particle aggregation. The results demonstrated that the droplet sizes and zeta potential values were consistent with expectations for SMEDDS formulations, with no irregularities observed (Table V). An example of the droplet size distribution is illustrated in Figure 2.

Table V: Globule size, Zeta potential and polydispersity index

Batch code

Droplet size (nm)

Polydispersity index

Zeta potential (mV)

F2
F3
F4
F5
F6

122,5

121,9

126,7

128,6

102,9

123,8

0,236

0,233

0,252

0,231

0,218

0,227

-15,5

-0,448

-6,9

-12,5

-0,177

-0,538

Figure 2: Size droplet of F1

SMEDDS-based formulations offer many advantages over conventional formulations:

· Stability: since they contain no water, they have improved physical and/or chemical stability during long-term storage.

· Compliance: Most SMEDDS formulations are available in capsule or tablet forms. These forms are space-efficient and easy to administer, ultimately improving patient compliance^22,23.

· Ease of production and scale-up: SMEDDS provide the benefit of straightforward large-scale production, requiring only basic, cost-effective equipment such as a standard mixer with an agitator and volumetric filling machinery for liquids²⁴.

· Rapid onset of action: SMEDDS have the distinctive feature of promoting rapid oral absorption of the drug, resulting in a rapid onset of action.

It should also be noted that, in the literature, numerous studies have been carried out with a view to establishing SMEDDS formulations based on various active compounds^25-29.

CONCLUSION:

The formulation and evaluation of a self-microemulsifying drug delivery system (SMEDDS) for ciprofloxacin, using argan oil as an excipient demonstrated that the developed formulation exhibited favorable physicochemical characteristics, including improved solubility and increased stability. This promising formulation approach offers a potential avenue to improve the delivery of ciprofloxacin, paving the way for future applications in drug formulation.

REFERENCES:

1. Kumar, P, Chaudhary M, Juyal V. Difference Spectroscopy Validated Method Development for Ciprofloxacin in Tablet by UV-Spectrophotometer. Research Journal of Pharmacy and Technology. 2009; 2(4): 780-782

2. Caço A-I, Varanda F, Pratas de Melo M-J, Dias A-M-A, Dohrn R, Marrucho I-M. Solubility of Antibiotics in Different Solvents. Part II. Non-Hydrochloride Forms of Tetracycline and Ciprofloxacin. Ind. Eng. Chem. Res. 2008; 47: 8083–8089. doi: 10.1021/ie8003495.

3. Olivera M-E, Manzo R.H., Junginger H.E., Midha K-K, Shah V.P., Stavchansky S, Dressman J-B, Barends D-M. Biowaiver Monographs for Immediate Release Solid Oral Dosage Forms: Ciprofloxacin Hydrochloride. J. Pharm. Sci. 2011; 100: 22–33. doi: 10.1002/jps.22259.

4. Raval A-J, Patel M-M. Techniques to Improve Bioavailability of Poorly Water Soluble Drugs–A review. Research Journal of Pharmaceutical Dosage Forms and Technology. 2011; 3(5): 183-192

5. Patil P, Mahajan, V-R. Self-Emulsifying Drug Delivery Systems (SEDDS): A Brief Review. Research Journal of Pharmaceutical Dosage Forms and Technology. 2014; 6(2): 134-139.

6. Panyam J, Labhasetwar V. Biodegradable nanoparticles for drug and gene delivery to cells and tissue. Advanced Drug Delivery Reviews. 2003; 55(3): 329–347. doi: 10.1016/S0169-409X(02)00228-4

7. Shrestha H, Bala R, Arora S. Lipid-Based Drug Delivery Systems. J Pharm (Cairo). 2014;2014:801820. doi: 10.1155/2014/801820.

8. GuruduttaP, Parmar J-U, SajidA-M, TahirA-M. Self-emulsifying drug delivery systems: An attempt to improve oral absorption of poorly soluble drugs. Research Journal of Pharmaceutical Dosage Forms and Technology. 2010; 2(3): 206-214

9. Sarode S-M, ChaudhariM-A, Kale M-K,VidyasagarG. Preparation and Characterization of Self Emulsifying Drug Delivery System (SEDDS). Research Journal of Pharmaceutical Dosage Forms and Technology. 2010; 2(4): 290-294.

10. Wei Y, Ye X, Shang X, et al. Enhanced oral bioavailability of silybin by a supersaturatable self-emulsifying drug delivery system (S-SEDDS). Colloids Surf A PhysicochemEngAspects. 2012; 396: 22–8. https://doi.org/10.1016/j.colsurfa.2011.12.025

11. Potphode V-R, DeshmukhA-S, MahajanV-R. Self-micro emulsifying drug delivery system: an approach for enhancement of bioavailability of poorly water soluble drugs. Asian Journal of Pharmacy and Technology. 2016; 6(3): 159-168. doi: 10.5958/2231-5713.2016.00023.4

12. MostafaS, El-SadekM, AllaE-A. Spectrophotometric determination of ciprofloxacin, enrofloxacin and pefloxacin through charge transfer complex formation. Journal of Pharmaceutical and Biomedical Analysis. 2002; 27(1-2): 133-142. doi: 10.1016/s0731-7085(01)00524-6

13. V. B. Borhade. Study of specialized emulsions for drug delivery (Masters thesis). University of Mumbai, India, 2006.

14. R. N. Gursoy and S. Benita. Self-emulsifying drug delivery systems (SEDDS) for improved oral delivery of lipophilic drugs. Biomed. Pharmacother. 2004; 58: 173–182. doi: 10.1016/j.biopha.2004.02.001

15. GoikU, GoikT, ZałęskaI. The properties and application of argan oil in cosmetology. European Journal of Lipid Science and Technology. 2019; 121(4): 1800313. doi:10.1002/ejlt.201800313

16. Shambhu Dokania & Amita K. Joshi. Self-microemulsifying drug delivery system (SMEDDS) – challenges and road ahead. Drug Delivery. 2015; 22(6): 675-690. doi: 10.3109/10717544.2014.896058

17. T. Kommuru, B. Gurley, M. Khan, et al., Self-emulsifying drug delivery systems (SEDDS) of coenzyme Q10: formulation development and bioavailability assessment, Int. J. Pharm 2001; 212(2): 233-46. doi: 10.1016/s0378-5173(00)00614-1.

18. C.W. Pouton, Formulation of self-emulsifying drug delivery systems, Adv. Drug Deliv. Rev. 1997; 25(1): 47–58. doi:10.1016/S0169-409X(96)00490-5

19. S.A. Charman, W.N. Charman, M.C. Rogge, et al., Self-emulsifying drug delivery systems: formulation and biopharmaceutic evaluation of an investigational lipophilic compound, Pharmaceut. Res. 1992; 9(1): 87-93. doi: 10.1023/a:1018987928936.

20. Gershanik, T.; Benzeno, S.; Benita, S. Interaction of a self-emulsifying lipid drug delivery system with the inverted rat intestinal mucosa as a function of droplet size and surface charge. Pharm. Res1998; 15(6): 863-9. doi: 10.1023/a:1011968313933.

21. Czajkowska-Kośnik A, Szekalska M, Amelian A, Szymańska E, Winnicka K. Development and Evaluation of Liquid and Solid Self-Emulsifying Drug Delivery Systems for Atorvastatin. Molecules. 2015; 20(12): 21010-22. doi: 10.3390/molecules201219745.

22. Gao P, Rush BD, Pfund WP. Development of a supersaturable SEDDS (S-SEDDS) formulation of paclitaxel with improved oral bioavailability. J Pharm Sci. 2003; 92(12): 2386-98. doi: 10.1002/jps.10511.

23. Gao P, Rush BD, Pfund WP. Development of a supersaturable SEDDS (S-SEDDS) formulation of paclitaxel with improved oral bioavailability. J PharmSci. 92: 2386–98. doi: 10.1002/jps.10511

24. Sander C, Holm P. Porous magnesium aluminometasilicate tablets as carrier of a cyclosporine self-emulsifying formulation. AAPS PharmSciTech. 2009; 10(4): 1388-95. doi: 10.1208/s12249-009-9340-0.

25. WarkeS, Warke-P, KaleM-K, SainiV. Formulation Design and Evaluation of Herbal Self Micro Emulsifying Drug Delivery System (SMEDDS). Research Journal of Pharmacy and Technology. 2011; 4(7): 1135-1140

26. Khansili A, BajpaiM. Formulation, evaluation and characterization of solid self-micro emulsifying drug delivery system (solid SMEDDS) containing nifedipine. Research Journal of Pharmacy and Technology. 2013; 6(3): 278-284

27. Dhairyasheel G, Adhikrao Y,Varsha G. Design and development of solid self-microemulsifying drug delivery of gefitinib. Asian Journal of Pharmacy and Technology. 2018; 8(4): 193-199

28. PawarP-P, PhadtareD-G. UV Spectrophotometric Method Development and Validation of Lornoxicam Loaded Solid SMEDDS. Research Journal of Pharmaceutical Dosage Forms and Technology. 2016; 8(4): 269-272.

29. Ponnaganti H, AbbuluK. Enhanced dissolution of repaglinide: SMEDDS formulation and in-vitro evaluation. Research Journal of Pharmacy and Technology. 2014; 7(11): 1246-1252.

Received on 19.03.2024 Revised on 22.06.2024

Accepted on 27.09.2024 Published on 20.01.2025

Available online from January 27, 2025

Research J. Pharmacy and Technology. 2025;18(1):312-316.

DOI: 10.52711/0974-360X.2025.00048

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