Keratitis

CONTROLLED RELEASE TECHNOLOGY - PHARMACEUTICAL] pol7) Mycotic keratitis treatment of... 

Amino-5-iodo-2, 5 -dideoxyuridine [56045-73-9] (13) C2H22IN2O4, was synthesized ia 1975 (27) and was found effective against herpes keratitis ia rabbits (28). This compound is markedly less cytotoxic than IdU, iadicating that it may have a safer and more specific mode of antiviral activity. A potential limitation of this group of nucleosides is their specificity, for they fail to inhibit all strains of herpes vimses. The specific antiviral activity of (13) is considered to be a result of the incorporation of the 5 -Ai-phosphate into both viral and host DNA in infected cells, but not into the DNA of normal cells. Phosphorylation of (13) occurs only in herpes vims-infected cells, brought about by a vims-induced thymidine kinase (29). 

Trifluridine, C2qH22F2N20, (5-trifluoromethyl-2 -deoxyuridine [70-00-8] F TdU, 14) was first prepared (30) in 1962. It is used for topical therapy of herpes vims-infected eyes. It is especially usefiil for treating infections that are resistant to IdU therapy. Like IdU, trifluridine is incorporated into DNA in place of thymidine in both infected and uninfected cells. But it is 10 times more potent than IdU against herpes keratitis in rabbits and 10 times more soluble in water. Trifluridine is also usefiil in treating human cytomegalovims (HCMV), but its toxicity to bone marrow may limit its clinical use. 

Topical apphcation of ara-HxMP, C2QH23N40gP, significantly inhibited the development of keratitis-induced HSV-1, HSV-2, or vaccinia vims in the eyes of rabbits. Ara-HxMP also significantly controlled the development of HSV-1 or vaccinia viral-induced encephaUtis in mice and was also active in preventing equine abortion viral deaths in hamsters. Clinical trials with ara-HxMP have not yet been reported. 

Acute infection with Hetpes simplex viruses (HSV) results in painful rashes on skin and mucous membranes. HSV-1 mainly causes cold sores around the mouth (hetpes labialis) or eyes (keratitis), whereas infection by HSV-2 mostly results in sores in the genital or anal area. Less frequently, HSV also causes severe infections in newborns or potentially fatal encephalitis. HSV remains latent and can be reactivated by stress, suppression of the immune system or other infections. 

Severe acute and chronic allergic and inflammatory processes, keratitis, allergic corneal marginal ulcers, herpes zoster of the eye, iritis, iridocyclitis, chorioretinitis, diffuse posterior uveitis, optic neuritis, sympathetic ophthalmia, anterior segment inflammation... 

These drugp possess anti-inflammatory activity and are used for inflammatory conditions, such as allergic conjunctivitis, keratitis, herpes zoster keratitis, and inflammation of the iris. Corticosteroids also may be used after injury to the cornea or after corneal transplants to prevent rejection. 

These drug are contraindicated in individuals with known hypersensitivity to an individual drug or any components of the drug. The NSA.ID flurbiprofen is contraindicated in patients with herpes simplex keratitis. Diclofenac and ketorolac are contraindicated in patients who wear soft contact lenses (may cause ocular irritation). 

The corticosteroid ophthalmic preparations are contraindicated in patients with acute superficial heq es simplex keratitis, fungal disease of the eye, or viral diseases of the eye, and after removal of a superficial comeal foreign body. 

The antibiotic and sulfonamide ophthalmics are contraindicated in patients with a hypersensitivity to the drug or any component of the drug. These dru are also contraindicated in patients with epithelial herpes simplex keratitis, varicella, mycobacterial infection of the eye, and fungal diseases of the eye There are no significant precautions or interactions when the dru are administered as directed by the primary health care provider. 

People who should not work with organophosphate insecticides are those with organic central nervous system disease, mental disorders, epilepsy, pronounced endocrine disorders, respiratory conditions, cardiovascular diseases, circulatory disorders, gastroenteric diseases, liver or kidney disease, and chronic conjunctivitis and keratitis (Medved and Kagan 1983). 

It has been shown that glycolic acid has a kerat-olytic, germinative layer and a fibroblast stimulating action. 

Figure 9.7 Mild anterior uveitis. Collections of macrophages (keratic precipitates) can be seen on the endothelial surface of the cornea (arrowheads).

Ophthalmic ointment, drops, or taping the eyelids shut to prevent keratitis and corneal abrasion... 

Local side effects are usually tolerable and may be caused by preservatives, therefore switching from one product to another may alleviate the local side effects. Stinging of the eyes upon instillation is the most common adverse effect. Other local adverse effects include conjunctivitis, keratitis, dry eyes, and uveitis.10,13... 

Untreated bacterial keratitis is associated with corneal scarring and potential loss of vision. Corneal perforation may cause the loss of the eye. 

The rate of progression of signs and symptoms varies depending on the infecting organism. A differential diagnosis for keratitis must include viral, fungal, and nematodal infections in addition to bacterial causes.19... 

Culture if keratitis is severe or sight-threatening. Otherwise, cultures or smears are used only if the corneal infiltrate is chronic or unresponsive to broad-spectrum antimicrobial therapy.19... 

Thirty thousand cases of microbial keratitis occur annually in the United States.18 Microbial keratitis encompasses bacterial, fungal, and Acanthamoeba keratitis.19 Only bacterial keratitis, the most common form, is discussed here. 

Bacterial keratitis is a broad term for a bacterial infection of the cornea. This includes corneal ulcers and corneal abscesses. The cornea in a healthy eye has natural resistance to infection, making bacterial keratitis rare. However, many factors predispose a patient to bacterial infection by compromising the defense mechanisms of the eye (Table 60-5).19... 

The most common pathogens in bacterial keratitis are Pseudomonas (including Pseudomonas aeruginosa) and other gram-negative rods, staphylococci, and streptococci. If the keratitis is related to the use of contacts, Pseudomonas is the most common cause followed by Serratia marcescens. For hospitalized infants and adults on respirators, Pseudomonas is the most common.19... 

Untreated bacterial keratitis is associated with corneal scarring and potential loss of vision. Corneal perforation may occur and the patient may lose the eye. In virulent organisms, this destruction may occur within 24 hours. Central corneal scarring may result in vision loss even after successful eradication of the organism. 

Unknown or multiple organisms Fluoroquinolones 3 mg/mL Severe keratitis loading dose every 5-1 5 minutes for the... 

Gram-negative rods Tobramycin 3-14 mg/mL or Gentamicin 3-14 mg/mL or Ceftazidime SO mg/mL or Fluoroquinolones 3 mg/mL Less severe keratitis may use less frequent dosing Antibiotics may be alternated each hour for ulcers and contact lens... 

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