carbenicillin disodium /kär′bənəsil″in/ , a semisynthetic penicillin antibiotic with an extended spectrum that includes Pseudomonas aeruginosa. ▪ INDICATIONS: It is prescribed in the treatment of certain infections caused by sensitive gram-negative aerobic bacilli. ▪ CONTRAINDICATIONS: Known hypersensitivity to this drug or to other penicillins prohibits its use. ▪ ADVERSE EFFECTS: Among the more serious adverse effects are hypersensitivity reactions, neurological disturbances, and clotting defects. The high sodium content (5.5 to 6.5 mEq/g) may aggravate fluid and electrolyte imbalance in people affected with kidney, heart, or liver disease.