Medications may be mixed into the fluids mentioned above, commonly normal saline, or dextrose solutions. Compared with other routes of administration, such as oral medications, the IV route is the fastest way to deliver fluids and medications throughout the body. For this reason, the IV route is commonly preferred in emergency situations or when a fast onset of action is desirable. In extremely high blood pressure (termed a hypertensive emergency), IV antihypertensives may be given to quickly decrease the blood pressure in a controlled manner to prevent organ damage. In atrial fibrillation, IV amiodarone may be administered to attempt to restore normal heart rhythm. IV medications can also be used for chronic health conditions such as cancer, for which chemotherapy drugs are commonly administered intravenously. In some cases, such as with vancomycin, a loading or bolus dose of medicine is given before beginning a dosing regimen to more quickly increase the concentration of medication in the blood.