This is a first-in-human phase 1 study to assess if ACHN-490 Injection is safe in people. Groups of people will receive either the study medication (ACHN-490) or a placebo (normal saline) as a single infusion. If the single dose is well tolerated then this group will receive 1 dose per day for up to 10 consecutive days. A new group of people will receive the study medication at a higher dose than the previous dose level as long as the previous dose was safe.

Inclusion Criteria:

• Men or women
• Within normal weight limits
• In good health with normal routine laboratory results
• Willing to not use media players (such as MP3 players) or devices with ear pieces and avoid exposure to loud noise

Exclusion Criteria:

• No ongoing medical conditions such as heart disease, high blood pressure, asthma, diabetes, seizures, or kidney problems
• No problems with hearing or balance
• No previous injury or surgery the the ears
• No family history of hearing loss before the age of 65
• Not taking any medication other than birth control medication
• Smokers or use of tobacco products
• Recent blood donor
• Allergy ot iodine, shellfish or aminoglycosides (a type of antibiotic)