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Eye is the unique organ of sight. conventionally various dosage forms are used but due to meagre bioavailability and residence time pharma researchers are trying for newer ocular dosage forms like in-situ gel, ocular films, ocuserts, liposomes, niosomes, dendrimers, collagen shields, SODI,biodegradable eye wafers and cones,iontophoresis etc. in this presentation more emphasis is given on in-situ gel forming techniques from various methods like pH, temperature and change in electrolyte composition. various polymers used for this purpose and very interesting rule of seven in eye also mentioned.
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1Kamal Singh Rathore*, 2Nema R.K., *1BN Girls College of Pharmacy, Udaipur-
Raj.3130022Rishiraj College of Pharmacy, Indore-M.P.
[email protected]+919828325713(M)
Eye anatomy Rule of seven in eye anatomy:•Weight of both spheres:≈7.0 gm•Volume of eye: ≈7.0 mL•Circumference of eye: ≈ 7.0 cm•Total protein in eye: ≈0.7% w/v•Total sugar present: ≈0.7% w/v•Total NaCl present: ≈ 0.7% w/v•Total mineral elements(Na+, K+. NH3+): ≈0.7% w/v•Volume of lachrymal fluid : ≈7.0 μl•Corneal surface epithelial intracellular pore size: ≈0.7 nm•Protein in blood: ≈7.0% w/v
and•pH of lachrymal fluid (tears): ≈ 7.0
Conventional dosage formsThe conventional ocular dosage forms for the
delivery of drugs areEye dropsEye ointmentsEye lotion
Limitations of conventional dosage forms
EVAPOPORATION OF TEARS
CORNEAL ABSORPTION
CONJUNCTIVALABSORPTION
NORMAL TEARTURNOVER
INDUCEDLACRIMATION
DRINAGE
DRUGMETABOLISM
DRUG-PROTININTERACTION
INSTILLED DOSE
Elimination of Instilled via Different routes
PRECORNEAL AREA
Fig.No-2
The recent trends in ophthalmic drug delivery
Mucoadhesive dosage forms:Phase Transition systems: in-situ gellingOcular Inserts or films: SODI, NODS, Lacrisert,
BODI, Dry drops and gelfoams, minidiscsCollagen shieldsDrug presoaked hydrogel type contact lens and
pledgetsOcular Iontophoresis (Pulsatile drug delivery)Chemical delivery systems vesicular systems:
Microspheres, microparticles, Nanoparticles, liposomes, niosomes, and PEGylation, dendrimers
The poor bioavailability and therapeutic response exhibited by conventional ophthalmic solutions due to rapid precorneal elimination of the drug may be overcome by the use of in situ gel-forming systems that are instilled as drops into the eye and undergo a sol–gel transition in the cul-de-sac.
IN-SITU SYSTEM
In-situ: at the placeImproved local bioavailabilityReduced dose concentrationLess total drugImproved patient acceptabilityReduced dosing frequency
Advantages of in-situ forming gel:Generally more comfortable than insoluble or soluble
insertionLess blurred vision as compared to ointmentIncreased bioavailability due to –
Increased precorneal residence time Decreased nasolacrimal drainage of the drug
Chances of undesirable side effects arising due to systemic absorption of the drug through naso-lacrimal duct is reduced
Drug effect is prolonged hence frequent instillation of drug is not required
The carbomer polymeric gel base itself has been used successfully to treat moderate to severe cases of dry eye such as Keratoconjuctivitis Sicca.
In-situ gelling systemIn situ-forming hydrogels are liquid upon
instillation and undergo phase transition in the ocular cul-de-sac to form visco-elastic gel and this provides a response to environmental changes.
ISGS three methods:-Change in pHChange in temperatureIon activation
Change in temperatureSustained drug delivery can be achieved by
use of a polymer that changes from sol to gel at the temperature of the eye. Temperature dependent systems include pluronics and tetronics. The poloxamers F127 are polyols with thermal gelling properties whose solution viscosity increases when the temperature is raised to the eye temperature (32-34C) from a critical temperature (16C).
Change in pHpH triggered systems show sol to gel transformation when
the pH is raised by the tear fluid to pH 7.4. pH triggered systems include-
cellulose acetate hydrogen phthalate latex, (pH 5.0 to 7.2-7.4 forms a gel with LF).
Carbopol (polyacrylic acid 0.5%, polycarbophil) pH 4.0 to 7.4 sol to gel transformation
Cellulose acetophthlate (CAP) is a polymer with potentially useful properties for sustained drug delivery to the eye, since latex is a free flowing solution at a pH of 4.4 which undergoes coagulation when the pH is raised by the tear fluid of pH 7.4.
pH triggered in-situ gelling system are low viscosity polymeric dispersion in water which undergoes spontaneous coagulation and gelation after instillation in conjuctival cul-de-sac.
Change in electrolyte compositionIon activated system show sol to gel
transformation in the presence of the mono or divalent cations (Na+, Ca2+ etc.)typically found in the tear fluids.
Ion activated system include Gelrite® (Gomme gellan) and alginates. Gellan gum is an anionic extracellular polysaccharide secreted by Pseudomonas elodea. Gellan gum formulated in aqueous solution, forms clear gels in the presence of the mono or divalent cations.
These system shows sol to gel transformation in the presence of ions.
Drug Formulation approach Polymers/Bases Reference(s) Indomethacine In-situ Gelling System Gellan Gum (Balasubramaniam Et Al.,
2003) Pefloxacin mesylate In-situ Gelling System Gellan Gum (Sultana et al., 2006a) Pilocarpine In-situ Gelling System Alginate (Cohen Et Al., 1997) Carteolol In-situ Gelling System Alginate (Demailly Et Al., 2001) Gatifloxacin In-situ Gelling System Alginate/HPMC (Liu Et Al., 2006) Ofloxacin In-situ Gelling System Carbopol® 940/HPMC (Srividya Et Al., 2001) Ciprofloxacin In-situ Gelling System Poloxamer/Hyaluronic Acid (Cho Et Al., 2003) Pilocarpine In-situ Gelling System Pluronic F127, MC, HPMC (Desai &
Blanchard, 1998) Pilocarpine In-situ Gelling System Pluronic F127/Carbopol (Lin & Sung, 2000) Pilocarpine In-situ Gelling System Pluronic F127, Xyloglucan (Miyazaki Et Al.,
2001) Timolol in-situ gelling system Pluronic F127, CMC, HPMC (El-Kamel, 2002)
Conclusion In-situ gel offers-easy, accurate and
reproducible administration of a dose,patient compliance, effective alternative to conventional dosage form,
can easily be instilled in liquid form, but are capable of prolonging the residence time of the formulation on the surface of the eye
ability to release drug in sustained manner, assist enhancing ocular bioavailability, flexibility in design system with desirable rheological properties and drug release rate.
References
Liu Z; Pan W; Nie S; Zhang L; Yang X; Li J, Preparation and evaluation of sustained ophthalmic gel of enoxacin Drug Dev Ind Pharm. 2005; 31(10):969-75
Balasubramaniam J; Pandit JK, Ion-activated in situ gelling systems for sustained ophthalmic delivery of ciprofloxacin hydrochloride. Drug Deliv. 2003; 10(3):185-91.
Liu Z; Li J; Nie S; Liu H; Ding P; Pan W, Study of an alginate/HPMC-based in situ gelling ophthalmic delivery system for gatifloxacin. Int J Pharm. 2006; 315(1-2):12-7
Kaur IP; Kanwar M., Ocular preparations: the formulation approach. Drug Dev Ind Pharm. 2002; 28(5):473-93
Srividya B; Cardoza RM; Amin PD, Sustained ophthalmic delivery of ofloxacin from a pH triggered in situ gelling system. J Control Release. 2001; 73(2-3):205-11
Sultana Y; Aqil M; Ali A; Zafar S, Evaluation of carbopol-methyl cellulose based sustained-release ocular delivery system for pefloxacin mesylate using rabbit eye model. Pharm Dev Technol. 2006; 11(3):313-9
Balasubramaniam J; Kant S; Pandit JK, In vitro and in vivo evaluation of the Gelrite gellan gum-based ocular delivery system for indomethacin Acta Pharm. 2003;53(4):251-61
El-Kamel AH, In vitro and in vivo evaluation of Pluronic F127-based ocular delivery system for timolol maleate.Int J Pharm. 2002; 241(1):47-55
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