Generic name: Rifabutin.

Proprietary name: Mycobutin.

Primary use

This agent is used in the treatment of Mycobacterium avium, leprosy tuberculosis, staphylococcal infections, brucellosis, HIV patients, atypical mycobacteria and Legionnaires’ disease. It is also used in the prophylaxis of Haemophilus, meningococcal meningitis and Mycobacterium avium.

Ocular side effects

Systemic administration

Certain

1.Uveitis

a.Anterior (from fine stellate keratic precipitates to large hypopyon)

b.Posterior

c.Panuveitis

d.Hypopyon

2.Blurred vision

3.Photophobia

4.Pain

5.Conjunctiva

a.Hyperemia

b.Micro-hemorrhages

6.Vitreous

a.Vitritis

b.Yellow-white opacities

7.Contact lens staining

8.Retina

a.Micro-hemorrhages

b.Vasculitis

9.Eyelids

a.Contact dermatitis

b.Rashes

c.Orange-tan discoloration

10. Cornea

a. Endothelial fine or large stellate deposits (Fig. 7.1j) 11. Lacrimation – rose colored

Probable

1. Staining IOL – rose color

2. Macular edema

Conditional/Unclassified

1. Cornea

a.Opacities

b.Ulcers

Clinical significance

Uveitis associated with rifabutin is the predominant ocular side effect with this drug. Fraunfelder and Rosenbaum (1997) reported 113 cases of rifabutin-associated uveitis from a spontaneous reporting systems database. Shafran et al (1994) performed a prospective randomized study of 119 patients, 59 of whom received rifabutin in combination with clarithromycin and ethambutol. About 40% of those who received rifabutin developed uveitis, about two thirds bilateral, with an onset mean of 65 days. The uveitis may occur within 2 weeks to 7 months after starting the drug. The inflammatory-like response may involve only the anterior segment or, rarely, the whole uvea. It may be mild, with only fine peripheral endothelial deposits without uveitis, to a fulminating panuveitis with significant posterior corneal and vitreal deposits. It may or may not be associated with hypo­ pyon, significant vitritis, including vitreal opacities (Chaknis et al 1996), or in rare instances, a retinal vasculitis. While it is most commonly associated with HIV-infected patients who are often on other antibiotics concomitantly, this entity is now ­being reported in immune suppressed patients, patients without AIDS, on rifabutin alone and in immune competent persons. The uveitis is more common in patients on rifabutin along with clarithromycin or fluconazole. These agents may elevate rifabutin serum levels by inhibition of the hepatic microsomal cytochrome P450 system, which metabolizes rifabutin. The uveitis is unique, in part because topical ocular steroids, even in fulminating cases, often clear the intraocular inflammation quite rapidly (Jacobs et al 1994). This ocular inflammatory response clears on topical ocular steroids and stopping the drug. There are a few cases where the drug was not discontinued and the uveitis cleared on its own. The etiology of this uveitis is unknown, and some postulate the possibility of interaction of multiple drugs,