SPECIAL SOLUTIONS AND

SUSPENSIONS

Have additional requirements

OPHTHALMIC DRUG DELIVERY

PHARMACOLOGIC CATEGORIES OF OPHTHALMIC DRUGS

Anesthetics – employed to provide pain relief preoperatively, postoperatively, for ophthalmic trauma and during ophthalmic examinations.

Examples: tetracaine, cocaine, proparacaine

ANESTHETIC

Antibiotic and anti-microbial agents – used systematically and locally to combat ophthalmic infection.

Examples: azithromycin, gentamicin sulfate, sodium sulfacetamide, ciprofloxacin, hydrochloride, ofloxacin, polymyxin B-bacitracin and tobramycin

ANTIBACTERIAL AND ANTIMICROBIAL

Antifungal agents – agents used topically on the eye against fungal endophtalmitis and fungal keratitis

Examples: amphotericin B, natamycin, flucytosine

Anti-inflammatory agents – used to treat inflammation of the eye, as allergic conjunctivites.

Examples: fluoromethalone, prednisolone, and dexamathasone salts.

Examples of non-steroidal: dicolfenac, flurbiprofen, keterolac and suprofen.

ANTI-INFLAMMATORY AGENTS

Anti-viral agents – used against viral infections that are caised by herpes simplex virus.

Examples: trifluridine, ganciclovir, vidarabine

ANTI-VIRAL AGENTS

Astringents – used in treatment of conjunctivitis

Examples: Zinc sulfate

Beta adrenergic blocking agents – used topically on the eye in the treatment of intraocular pressure and chronic open-angle glaucoma

Examples: betaloxolol HCl, levobunolol HCl, metipranolol HCl, timolol maleate

BETA ADRENERGIC BLOCKING AGENTS

Miotic and other glaucoma agents – used in the treatment fo glaucoma, accomodative esotropia, convergent strabismus, and for local treatment of myasthenia gravis.

Examples: pilocarpine, ecothiophate

MIOTIC AND OTHER GLAUCOMA AGENTS

Mydriatics and cycloplegics – allow the examination of the fundus by dilating the pupil. Mydriatics that have a long term of dilating are called cycloplegics

Examples: atropine, scopalamin, phenylephrine, hydroxyamphetamine, and tropicamide

MYDRIATICS AND CYCLOPLEGICS

Protectants and artificial tears – solutions employed as artificial tears or as contact lens fluids lubricate the eye

Examples: carboxy methyl cellulose, polivinyl alcohol

PROTECTANS AND ARTIFICIAL TEARS

Vasoconstrictors and ocular decongestants – applied topically to the mucuos membranes of the eye cause transient constriction of the conjunctival blood vessels. They are intended to soothe, refresh, and remove redness due to minor eye irritation.

Examples: naphazoline, oxymetazoline and tetrahydrazoline hydrochlorides.

VASOCONSTRICTORS

PHARMACEUTICAL REQUIREMENTS

STERILITY AND PRESERVATION -must be sterilized for safe useAutoclaving(in final containers) at 121

Celsius for 15 minutes is preferable but may cause thermal instability. So Bacterial Filters may be used.

To keep the steriliy during use, antimicrobial preservatives are generally included in opthalmic operations.

ISOTONICITY VALUE Opthalmic solutions should be isosmotic

at 0.9% NaCl solution because 0.9% NaCl is the corresponding osmotic pressure of the body fluids including blood and tears.

Hypertonic solutions may draw water from the body tissues toward the solution and may cause crenation(shrinking) of blood cells

Hypotonic solutions may cause hemolysis of blood cells or passage of water from the site of an ophthalmic application throught the tissues of the eye

BUFFERING For greater comfort to the eye Render the formulation more stable To enhance the aqueous solubility of the drug To enhance the bioavailability To maximize preservative efficacy

pH of normal tears are 7.4, but tears of contact lens wearers are more acidic.

Desired solution is prepared from two stock solutions, one containing 8g of monobasic sodium phosphate per liter and the other containing 9.47g of dibasic sodium phosphate per liter.

VISCOSITY AND THICKENING AGENTS Viscosity is a property of liquids related

to resistance to flow. Fluidity is the reciprocal of viscosity.

Thickening agents – methycellulose Used to increase ophthalmic solutions’

therapeutic effectiveness

ADDITIONAL CONSIDERATIONS Ophthlamic solutions must be sparkling

clear and free of all particulate matter for comfort and safety.

Drug particles in an ophthalmic suspension must be finely subdivided, usually micronized to minimize eye irritation and/or scratching of the cornea. The suspended particles must not associate into large particles upon storage and must be easily and uniformly redistributed by gentle shaking prior to use.

If large particles/crystals form and is placed on the eye, it may hurt like hell. Lol

PACKAGING OPHTHALMIC SOLUTIONS AND SUSPENSIONS Small glass bottles with seperate glass

or plastic dropepers. Most are packaged in soft plastic

containers w/ a fixed built in dropper. This is preferred both to facilitate administration and to protect the product from external contamination.

Patients must be careful to protect ophthalmic solutions or suspensions from external contamination

PROPER ADMINISTRATION OF OPHTHALMIC SOLUTIONS AND SUSPENSIONS

- wash hands thoroughly - inspect dropper to make sure it has no

chips or cracks (if applicable) - ophthalmic solutions should be

inspected for color and clarity. Suspensions should be shakened prior to administration

To instill eyedrops: - patient should tilt head back with index finger

of the free hand gently pull downward the lower eyelid of the affected eye to form a pocket or cup.

- while looking up and w/out touching the dropper, prescribed number of the drops should be instilled into the formed pocket.

- lower eyelid should be released and the eye closed to allow the medication to spread over the eye. Eye should be held closed for 1 min. w/out blinking rubbing or wiping.

While eye is closed, gentle pressure should be applied just under the inner corner of the eye to compress the nasolacrimal duct to prevent drainage.

-excess liquid may be wiped with a tissue