fluids as well, but this discoloration disappears once the drug is discontinued. Ocular side effects seen with this drug appear to occur more frequently during intermittent treatment than ­during daily treatment and are reversible when the drug has been discontinued. In animals this drug accumulates in ocular pigment, but there are no data for this in humans.

Topical ocular use of 1% rifampicin ointment has been reported to cause approximately a 10% incidence of adverse ocular effects, which are primarily due to irritation and include ­discomfort, tearing, lid edema and conjunctival hyperemia. The irritation, discomfort and tearing usually last only 10–50 minutes after the application of the ointment.

References and Further Reading

Birch J, et al. Acquired color vision defects. In Pokorny J, Congenital and Acquired Color Vision Defects. Grune & Stratton, New York, 1979, p 243–350.

Bolan G, Laurie RE, Broome CV. Red man syndrome: Inadvertent administration of an excessive dose of rifampin to children in a day-care center. Pediatrics 77: 633, 1986.

Calissendorff B. Melanotropic drugs and retinal functions. Acta Ophthalmol 54: 118–128, 1976.

Cayley FE, Majumdar SK. Ocular toxicity due to rifampicin. BMJ 1: 199200, 1976.

Darougar S, et al. Topical therapy of hyperendemic trachoma with rifampicin,­ oxytetracycline, or spiramycin eye ointments.

Br J Ophthalmol 64: 37, 1980.

Fraunfelder FT. Orange tears. Am J Ophthalmol 89: 752, 1980. Girling DJ. Ocular toxicity due to rifampicin. BMJ 1: 585, 1976.

Grosset J, Leventis S. Adverse effects of rifampin. Rev Infect Dis 5(Suppl 3): 440, 1983.

Lyons RW. Orange contact lenses from rifampin. N Engl J Med 300: 372, 1979. Mangi RJ. Reactions to rifampin. N Engl J Med 294: 113, 1976.

Nyirenda R, Gill GV. Stevens-Johnson syndrome due to rifampicin. BMJ 2: 1189, 1977.

Generic name: Thioacetazone (Amithiozone).

Proprietary names: Conteben, Tibione.

Primary use

This tuberculostatic agent is effective against M. tuberculosis and M. leprae. This drug is also used for lupus vulgaris.

b.Stevens-Johnson syndrome

c.Exfoliative dermatitis

d.Lyell syndrome

Conditional/Unclassified

1. Retinal edema

2. Color vision defect

3. Scotoma

Clinical significance

Numerous adverse ocular reactions due to thioacetazone have been seen. Skin manifestations have been the most frequent. Nearly all ocular side effects are reversible and are of minor clinical significance. One instance of irreversible toxic amblyopia with a central scotoma and decreased color vision has been reported; however, the patient was also receiving aminosalicylic acid.

References and Further Reading

Mame-Thierna D, On S, Thierno-Nydiaye S, Ndiaye B. Lyell syndrome in Senegal: responsibility of thiacetazone. Ann Dermatol Venereol 128: 1305–1307, 2001.

Ravindran P, Joshi M. Dermatological hypersensitivity to thiacetazone. Indian J Chest Dis 16: 58, 1974.

In Reynolds JEF Martindale: The Extra Pharmacopoeia. 30th edn. Pharmaceutical Press, London, 1993, p 216–217.

Sahi SP, Chandra K. Thiacetazone-induced Stevens-Johnson syndrome: a case report. Indian J Chest Dis 16: 124, 1974.

Sarma OA. Reactions to thiacetazone. Indian J Chest Dis 18: 51, 1976.

SECTION 2

Agents Affecting the CNS

Class: Analeptics

Generic name: Gabapentin.

Proprietary name: Neurontin.

Primary use

This antiepileptic drug is used in refractory seizure patients.