Abstract

Microsponge is polymeric delivery system and a drug carrier which have tiny microscopic structure with a larger porous surface. These are micro-sized particle with average diameter of 5-30 micron. The pores of a microsponge are used for entrapment of drug. These are newer technologies which have been used to control the release of medicament from formulation and also it precises the drug in targeted delivery. Microsponges have several advantages like improved stability, extended release, improved bioavailability and précised drug targeting makes it a better carrier for drug than the conventional nanocarrier like liposome. Microsponges are formulated by various approaches in which quasi-emulsion solvent diffusion method. In this two phases (1) Internal organic phase (2) External aqueous phase are prepared separately. The organic phase contains drug and solvent (ethanol) with polymer (1-5% w/v) and outer phase contains water with surfactant (PVA) (0.1-1%w/v). The internal phase is added drop-wise to external phase with high speed continuous stirring that formulate porous microsponge after evaporation. Due to higher ranges of temperature tolerance up-to 130oC and Ph stability from 1-11, micrsponge are suitable opportunity for preparing stable formulation of wide range of drug categories. Microsponges were widely used in various drug deliveries like oral, drug delivery, topical drug delivery with uses in diseases like acne, diabetic wound healing, psoriasis, fungal infection, cancer etc.

Keywords

Introduction

       
           
       
Figure 01: - Structure of microsponge

History Of Microsponge:-

       
           
       
Figure 02: - Characteristics Of Microsponge

Advantages Of Microsponge^{14, 15, 16, 17}: -

       
           
       
   Figure 03:- Advantages Of Microsponges

Mechanism Of Drug Release From Microsponge:-

       
           
       
Figure 04: - Mechanism Of Drug Release from Microsponge

Pressure: - The release from microsponge is triggered by rubbing microsponge through the skin ^{20, 21.}

       
           
       
Figure     05: - Quasi-emulsion solvent diffusion method

       
           
       
Figure 06: - Chart showing Quasi-emulsion solvent diffusion method

Quasi-emulsion solvent evaporation ^29,30:-

       
           
       
Liquid-liquid suspension polymerization ^31,32:-

       
           
       
Figure 07: - Liquid-liquid suspension polymerization method

Water in oil emulsion solvent diffusion ³³: -

       
           
       
Figure 08:-Water in oil emulsion solvent diffusion method

Oil in oil emulsion solvent diffusion ³⁴:-

       
           
       
Figure 09: - addition of porogen method of preparation

Lyophilisation ³⁶:-

• The microsponges are lyophilized after incubating in chitosan hydrochloride solution.
• By lyophilisation rapid removal of solvent occurs. But due to rapid solvent elimination cracking, shrinkage may occur.

8. Vibrating orifice aerosol generator (VOAG) ³⁷:-

5. VOAG was first reported for the preparation of lipid bilayered mesoporous silica particles.
5. Tetra ethyl ortho silicate, ethanol, water and dil. HCl were refluxed to prepare stock solution for formation of care.
5. The stock solution is diluted with solvent containing surfactant and stirred to form mono dispersed droplets. The droplets were encapsulated in liposome.

Evaluaion Paramaeters Of Microsponge:-

1. Particle size determination
2. Morphology and surface topography
3. Determination of loading efficiency and production field
4. Drug entrapment 

1. Particle size determination³⁸-

For particle size distribution optical microscope is used. Diffractrometry can also be used to determine the particle size of microsponges.

The texture and stability of a formulation are affected by particle size.

2. Morphology³⁹–

For determination of morphology or surface morphology scanning electron microscopy is used.

The sample was mounted directly on to the SEM sample holder using double sided sticked tape. The images were recorded at different resolutions.

3. Production yield^40,41-

The production yield of microsponges can be calculated using formula.

x=Actual yieldTheoratical yield×100

 

4. Drug content ⁴²–

To measure drug content in microsponge 100 mg of precisely weighted microsponge is mixed in 100 ml of 6.8 ph phosphate buffer. The mixture is filtered through 0.45 µm membrane filter andsample is analyzed at suitable wavelength using UV.

Drugcontent=Actual amount of drugWeighed amount of sponge×100

 

5. Entrapment efficiency ^43,44-

Drug entrapment efficiency is assessed through solvent extraction method.

10 mg of precisely weighed microsponge is dissolved in 5ml of methanol using magnetic stirrer for 20 min.

20 ml of freshly prepared PBS is added and heated at 45-50^oC .Till the formation of clear solution. Methanol is evaporated and cooled at 25^oC and filtered.

The drug concentration is measured by UV.

DEE=Actual drug content of spongeTheoratical drug content of sponge×100

 

Application Of Microsponge in Different

Pharmaceutical Formulation:-

Figure10:- Application of microsponge

1. Microsponge for oral drug delivery:-

• Microsponge helps to maintain the drug in protected condition and protected release under regulated condition in lower GIT ^45.
• Microsponge increases absorption of medicament through small and large intestine by extending transit time ⁴⁶.
• There produced mechanically robust tablets of ketoprofen by quasi-emulsion solvent diffusion method of sponge formation. That prove plastic deformation of micosponge enhances compressibility ⁴⁷.
• Fluorbiprofen shows notable augmentation in drug release during 8^th hour due to inclusion of enzyme in colon results in colon-targeting ^48.

2. Microsponge for topical delivery: -

• Fluocinolone acetonide, a corticosteroid is employed in dermatology to eliminate skin irritation and improve inflammatory condition ⁴⁹.
• By incorporating benzoyl peroxide in micrsponge its percutaneous absorption lowers which causes lessen in skin-irritation ^{50, 51, 52.}
• Microsponge can be formulated in creams, gels, powders, lotions.
• Hydroquinolone bleaching creams shows prolong release to minimize skin irritation ⁵³.
• Zinc pyrithione, selenium sulphide when formulated in microsponge to be use in anti-dandruff shampoo shows reduction in unpleasant odour with lowered irritation with extended safety and efficacy ⁵⁴.

3. Microsponge in cosmetics: -

Microsponge helps in dismantling uniformity and improves covering power so colorful cosmetics can be prepared with microsponge ⁵⁵.

4. Microsponge for bone and tissue engineering: -

Two aqueous dispersion tricalcium phosphate granules and powdered calcium hydroxyapetite and prepolymerised polymethyl metha acrylate with methyl methaacrylate monomer liquid.

A collagen sheet encapsulating basic fibroblast growth factor (bFGF) when injected subcutaneously causes increase in blood rate ^{56, 57, 58}.

Uses Of Microsponge For Various Diseases

1. For psoriasis- Momentasonefurote is used in microsponge by emulsion solvent diffusion method shows initial rapid drug release effect with 29-30% drug release during first hour to 78-95 % drug release after 8 hour ^59,60,61,62.
2. For skin infection- Mupirocin microsponge incorporated in emulgel base could provide sustained drug release till 24 hours. In draize patch test these formulation are stable and safe use. This causes slow release and shows prolonged therapeutic effect ⁶³.
3. For diabetic wound healing-Nevibolol- loaded microspnge shows double effect of vasodilation with controlled and sustained release so promote faster healing. In in-vitro study 80% drug release shows within 8 hour and rapid and significant wound healing⁶⁴.
4. For fungal infection- Voriconazole prepared using quasi-solvent diffusion method shows high encapsulation efficiency than coventional fluconazole gel and shows greater zone of inhibition⁶⁵.
5. For acne- Benzoyl peroxide microsponge had a high drug loading capacity, sustained drug release and improved stability over conventional formulations.The microsponge gel shows greater reduction in acne lesions and skin irritation ^{66, 67}.
6. Atopic dermatitis- Nargenin 1% microsponge gel have 82% entrapment and shows faster healing, reduced earflap thickness, lower WBC counts as compared to plain gel. The main benefit is three-fold greater drug deposition onto skin⁶⁸.
7. Hyperpigmentation-glabrid microsponge using ethyl cellulose then formulated in gel causes reduction in melanin density ⁶⁹.
8. For skin cancer- 5- fluorouracil (5-FU) shows better surface area and pore volume and have improved texture and it shows 5.5 times increasein skin deposition and lessen skin irritation ^{70, 71}.
9. For Herpes-acyclovir loaded microsponge emulgel causes improved drug penetration than commercial formulation ^72.
10. For arithritis- diclofenac used in microsponge shows prolonged release for arithritis on topical application ^{73, 74.}

CONCLUSION

The microsponge delivery system is a unique technology for the controlled release of macroporous beads, loaded with an active agent, offering a potential reduction in side effects while maintaining their therapeutic efficacy. The microsponge delivery system is a novel, unique and emerging technology for controlled and prolonged release of drug.These are valuable drug matrix substance with several beneficial advantages like having good physical, chemical and thermal stability and allow greater flexibility in dosage from manufacturing and drug entrapment.  Microsponges drug delivery system is very emerging pharmaceutical application for controlled release system, it reduces irritancy, reduces toxicity and compatible with most of ingredient and vehicles. Synthesized through techniques like quasi-emulsion solvent difusion, they found use in dermatological and oral drug delivery. Now a days it can also used for tissue engineering and controlled oral delivery using bio-erodible polymers, especially for colon specific delivery. These were mainly used in cosmetics, but due to its versatility it is source of interest in drugs ofvarious field like NSAIDs, cancer, arthritis, acne, Diabetic wound etc. Due to its stability over wide range of temperature and ph range it is suitable area of research for various sensitive drugs and its ability to control drug and it can also be controlled drug delivery and biopharmaceutical drug delivery. Due to its larger pore area it is main choice for enhance drug entrapment and control release rate of drug from sphere. Microsponges represent a promising frontier in drug delivery, with potential across pharmaceutical and cosmetic domains. MDS holds a promising future in various pharmaceutical applications in the coming years as they have unique properties like extended release, reduced irritancy, small size, self sterilize and compatible with most of vehicles and ingredients, so flexible to develop novel product forms.

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