DƯỢC LÍ Goodman & Gilman's The Pharmacological Basis of Therapeutics 12th, 2010

Table 64–6
Antifungal Agents for Ophthalmic Use
DRUG CLASS/AGENT METHOD OF ADMINISTRATION INDICATIONS FOR USE
Polyenes
Amphotericin B a 0.1-0.5% (typically 0.15%) topical solution Yeast and fungal keratitis and endophthalmitis
0.8-1 mg subconjunctival Yeast and fungal endophthalmitis
5-μg intravitreal injection
Yeast and fungal endophthalmitis
Intravenous
Yeast and fungal endophthalmitis
Natamycin 5% topical suspension Yeast and fungal blepharitis, conjunctivitis, keratitis
Imidazoles
Fluconazole a Oral, intravenous Yeast keratitis and endophthalmitis
Itraconazole a Oral Yeast and fungal keratitis and endophthalmitis
Ketoconazole a Oral Yeast keratitis and endophthalmitis
Miconazole a 1% topical solution Yeast and fungal keratitis
5-10 mg subconjunctival Yeast and fungal endophthalmitis
10-μg intravitreal injection
Yeast and fungal endophthalmitis
a
Off-label use. Only natamycin (NATACYN) is commercially available and labeled for ophthalmic use. All other antifungal drugs are not labeled
for ophthalmic use and must be formulated for the given method of administration. For further dosing information, refer to the Physicians’ Desk
Reference for Ophthalmic Medicines. For additional discussion of these antifungal agents, see Chapter 57.
antiseptic agent polyhexamethylene biguanide (PHMB) also is used in
drop form for Acanthamoeba keratitis, although this is not an FDAapproved
antiprotozoal agent. Topical chlorhexidine can be used as
an alternative to PHMB. Oral imidazoles (e.g., itraconazole, fluconazole,
ketoconazole, voriconazole) often are used in addition to the topical
medications. Resolution of Acanthamoeba keratitis often requires
many months of treatment.
Toxoplasmosis may present as a posterior (e.g.,
focal retinochoroiditis, papillitis, vitritis, retinitis) or
occasionally as an anterior uveitis. Treatment is indicated
when inflammatory lesions encroach upon the
macula and threaten central visual acuity. Several regimens
have been recommended with concurrent use of
systemic steroids:
• pyrimethamine, sulfadiazine, and folinic acid (leucovorin)
• pyrimethamine, sulfadiazine, clindamycin, and
folinic acid
• sulfadiazine and clindamycin
• clindamycin
• trimethoprim-sulfamethoxazole with or without clindamycin
Other protozoal infections (e.g., giardiasis, leishmaniasis,
malaria) and helminths are less common eye
pathogens in the U.S. Systemic pharmacological management
as well as vitrectomy may be indicated for
selected parasitic infections.
In the eye, infections can occur in a variety of
locations, such as the cornea, sclera, vitreous, and retina
and can be caused by bacteria, viruses, fungi, and parasites.
Treatment is based on the severity of infection,
the location, and the class of infectious agent. Within
each group of microbial cause, different organisms are
treated with different medications. Gram-positive bacteria
respond to certain antibiotics and Gram-negative
bacteria to others. Some organisms are quite susceptible
to many antimicrobial agents, while others are not.
Still others may have been susceptible in the past but
have become resistant. The task of staying ahead of the
rapidly developing resistances is becoming increasingly
difficult. In ophthalmology, fortunately, newergeneration
topical fluoro quinolones recently were
brought to market, which has at least temporarily
helped stem the tide of resistant infections. Additional
topical fluoroquinolones are in development.
While the selection of topical antiviral agents is
rather limited, several new systemic antiviral agents have
become available in the past decade. Similarly, there is
only one commercially available topical antifungal
medication, but there are numerous systemic agents, several
of them new in the past few years. Potentially, some
of these systemic medications could be modified for topical
use or even formulated as intraocular implants,
greatly expanding our options in the treatment of many
ophthalmic infectious diseases.