Intracerebroventricular drug administration is a method that bypasses the blood-brain barrier and other mechanisms that limit drug distribution into the brain, allowing high drug concentrations to enter the central compartment. Instillation of drugs directly into the ventricles of the brain must be done carefully and with full consideration of factors affecting the efficacy and safety of this route of administration. These factors include the osmolarity, pH, volume, and presence of preservatives and diluents of the drug solution being administered. Very few studies have formally investigated intraventricular therapies, and dosing recommendations may vary widely depending on the agent and the patient. Many antimicrobials have been given intraventricularly, although very few prospective studies have evaluated this strategy. There are wide variations among the reports regarding dosage regimens and the pharmacokinetics of the antimicrobials used. Guidance on appropriate formulations and their use is lacking. Clinicians should be aware of their patients' ongoing disease processes and neurologic status, as well as pertinent physiochemical properties of drugs when formulating them for intracerebroventricular administration; a high index of suspicion should be maintained when monitoring patients for adverse drug events after instillation.