MS-2064

You are asked to evaluate a 4-year-old girl who has been brought to the clinic by her parents due to concerns over her development. While her motor development has been normal, her speech has been persistently delayed; she is still unable to put more than 2 words together to form a sentence, and often does not respond when called. Her parents are worried that she may have autism.

The child is referred for play audiometry, which reveals abnormalities. Upon taking a careful history, it is revealed that a drug given to the child to treat an infection in her first year of life may be responsible for her developmental delay.

Which of the following drugs is most likely to be responsible?