Pharmacodynamics refers to how the body is affected by the use of certain medications (Fox, Hawney, & Kaye. The patient is a tall, lanky 67-year-old male with end-stage renal failure and cirrhosis of the liver. He presents to the Emergency Department (ED) with an inguinal hernia that he cannot reduce. He rates his pain 10/10 on a scale of 1-10, with 0 being no pain and 10 being extreme pain. The patient appears uncomfortable, complains of dizziness, and constipation. Social history consists of smoking a pack a day or cigarettes for 25 years, moderate alcohol consumption, daily marijuana use, poor diet, and decreased mood. His medications are centered around pain control and include the use of narcotics every 4 hours. The patient is given a dose of Toradol 30mg, intravenously (IV). After ten minutes, the patient is asking for more pain medication. Fentanyl 50 mcg, IV is given with no pain relief reported by the patient. Finally, Hydromorphone 1mg, IV is administered. After an hour, the patient still reports pain 10/10.
Pharmacokinetics and Pharmacodynamics
Pharmacokinetics studies the absorption, distribution, metabolism, and excretion of drugs within the body system (Ball, Dains, Flynn, Solomon, & Stewart, 2019). The use of pharmacokinetics enables providers to determine the appropriate drug for a patient’s diagnosis. Pharmacodynamics refers to how the body is affected by the use of certain medications (Fox, Hawney, & Kaye, 2011). Due to the individualized nature of the human body, finding a drug that responds with minimal side effects are desired.Pharmacokinetics, as it relates to this patient’s pathophysiology, creates difficulty for the patient due to the diagnosis of kidney failure and cirrhosis. Cirrhosis of the liver prevents the body from absorbing, distributing, and metabolizing the drug. With significant disease process in effect, it is difficult for the body to absorb the drug at a rate that provides effective pain control. The first-pass metabolism with hydromorphone is decreased in liver cirrhosis and has a likelihood of high hepatic extraction (Wehrer, 2015). Whereas, fentanyl, is a protein-bound medication is reportedly unaffected by cirrhosis (Wehrer, 2015). Though the patient tolerated the fentanyl in our case, no specific relief is found due to the chronic nature of the pain. Decreased kidney function reduces the excretion of drugs from the body creating an accumulation of medication in the entire body (Ball et al., 2019). Frequent use of medications creates a tolerance to that medication and accelerates metabolism of the drug. Tolerance and increased metabolism results in ineffective pain management outcomes (Ball et al., 2019). The use of opioids for pain management, in this case, may create an antagonist effect causing unwanted consequences such as constipation, the potential for abuse, and withdrawal (Walter, Knothe, & Lotsch, 2016). Due to the patient’s continued alcohol consumption and disease processes, the use of acetaminophen or ibuprofen is not encouraged (Wehrer, 2015).
For the patient above, behavioral and pathophysiological changes are contributing factors for the choice of medications given. Alcohol use is the highest contributing factor to cirrhosis (Askgaard, Gronbaek, Kjaer, Tjonneland, & Tolstrup, 2015). This behavior, as well as smoking, will need to be eliminated to be on the transplant list. The pathophysiological changes created altered renal excretion and inability of the liver to metabolize medications given for pain control.
Personalized Plan of Care
The plan of care for this patient is to control the pain from the inguinal hernia until it can either be repaired or reduced. The ability to control pain at a level of 5/10 is the first goal. A discussion with the patient is necessary to establish realistic goals in light of the chronic conditions. Focusing on the pain from the hernia is our primary focus. Initiation of other medications for pain such as Ketamine, Benadryl, or Reglan can decrease pain by 50 percent. Lastly, non-medication alternatives such as positioning, distraction, and ice-therapy can provide temporary relief.