Pain killer drugs, also commonly known as analgesics, come in many forms, each with a different potency and mode of action. The choice of pain killer typically depends on tolerability as well as the severity of the pain. Cancer Help UK cites several common pain killer drugs called opioids that come in strengths that vary from mild to strong.
According to Cancer Help UK, morphine is one of the strongest opioids administered to patients. It comes in many preparations with each having its own mode of administration. There are patches that can be put on the skin, liquids that can be injected and tablets that can be put under the tongue to dissolve. MedlinePlus reports that while morphine is effective, it is also highly addictive and should be used under strict supervision. It is important that patients closely follow a physician's orders for dosage and administration to avoid problems such as addiction or overdose.
Diamorphine is a form of morphine that is dissolved in water and administered via injection with a syringe driver. A syringe driver is a battery operated pump that will administer the drug at fixed times as set by the doctors and nurses. These devices are normally used for patients recovering from surgery, or who may find it painful or impossible to swallow.
The slowest release medication on Cancer Help UK's list of strong pain killer drugs is fentanyl. Fentanyl is a synthetic opiod also commonly known as durogesic. The most common form of administration is through a patch on the skin that allows for drug absorption by the body. Once the patch is on the body, the medication is gradually released, so the highest possible level of pain relief is not immediately reached. If a patient has taken fentanyl, it will remain in the body for a minimum of 72 hours. Fentanyl is also administered as a tablet that can be put between the cheek and gum until it dissolves.