You are preparing to administer a liquid suspension. What must you do first?
Give it a series of good snappy shakes just before measuring the volume.
Medications that are suspensions tend to settle, with the solid aggregating on the bottom. Before the drug is administered, you give the bottle a good series of snappy shakes, so as to evenly suspend the particles in the mixture. At the moment, I can't think offhand of an example of such a drug. Even in a hospital, where the personnel are trained to deliver precise doses of medications, most drugs are delivered as tablets (with precise masses and dosage), or as homogeneous solutions, where volume corresponds to dosage.