Explain the need for preparing the following dosage forms as isotonic.
BAXTER POTASSIUM CHLORIDE (0.15% or 0.224%) AND 5% GLUCOSE (POTASSIUM CHLORIDE, GLUCOSE) INTRAVENOUS INFUSION (1000 mL pack)
Bupivacaine spinal heavy BNM (Injection solution to produce spinal anesthesia)
AUGMENTIN DUO 400 SUSPENSION
Ear drops