What method is commonly used for administering drugs that are soluble in liquids?

Injecting is a commonly used method for administering drugs that are soluble in liquids because it allows for direct entry of the drug into the bloodstream. This method is particularly effective for achieving rapid therapeutic effects since it bypasses the digestive system, enabling the substance to take effect more quickly than oral administration. Injecting can be done subcutaneously, intramuscularly, or intravenously, depending on the desired speed of absorption and the nature of the drug being administered.

Swallowing would not be suitable for immediate effects if rapid onset is needed, as it requires the drug to be digested and absorbed through the gastrointestinal tract. Inhaling can be effective for certain substances but primarily pertains to gases or vapors rather than liquid-soluble drugs. Smoking involves combusting a substance and inhaling the smoke, which is not applicable for drugs simply dissolved in liquid form. Therefore, injecting is the most appropriate and commonly employed method for liquid-soluble drugs.