Pharmacokinetics and Pharmacodynamics

Pharmacokineticsand Pharmacodynamics

Pharmacokineticsand pharmacodynamics are a very important study factor that enablesphysicians to prescribe treatment to a patient. Various patientsrespond differently to the drugs given to them due to their bodies’activities towards the drug. The pharmacodynamics factors such assuppression of pain and pharmacokinetics such as metabolism, drugdistribution and its excretion. Some drugs are much better given tothe patient through intravenous injections rather than oral. This iswell explained in the case of insulin for diabetes patients where thedrug is a hormone and protein in nature (Angiolillo,et al. 2011).Therefore, if administered orally, then it will be digested by thepepsin enzyme found in the gastro-intestinal tract before it gets tothe blood where its effect is manifested.

Propofolis a common sedative drug used for the conservation of anesthesia.The drug’s sedative effect is directed towards the predominantGABA receptors noted on the ligand-gated ion channels. It inhibitsthe chloride ion channels on the pre-synaptic and postsynaptic neuron hence exerting its anticonvulsant property. In somepathophysiological conditions a clinician may be force to reduce thedosage to achieve the optimal 50% effect[ CITATION Ric10 l 1033 ].

Anexample of a clinical case is whereby a patient code named Mr.Lukewas scheduled to undergo reconstructive surgery. We administered theusual dosage of 2.5mg/kg of propofol but the patient underwentcardiovascular collapse with hypotension. Upon realization that hepresented with symptoms of hemorrhagic shock, we had to reduce thedosage to 1.2mg/kg. According to Oullette et al, some of the factorsthat necessitate reduction of dosage in hemorrhagic shock includereduction in cardiac output and increased peak plasma levels ofpropofol[ CITATION Ric10 l 1033 ].

Whenhe was put on the propofol, we discovered sedation was not prolongedas expected. This lead to confirming his hemoglobin levels were verylow. This patient had lost much blood. Hemorrhage had been the maincause of his failed sedation. According to Johnson et al, hemorrhagicshock has been attributed to alteration in pharmacodynamics andpharmacokinetics of propofol drug (JM, 2012).

Iwould undertake the following procedures to counter any cases ofhemorrhagic shock and hypovolemic I will check the patient`s airwayand allow adequate air circulation, begin an intravenous infusionusing normal saline, draw blood and check the arterial blood gasesand measure the patient’s urine output. I would also refer to thepatient’s disease history to ensure no chances of wrong treatmentor dosages.[ CITATION Ric10 l 1033 ]


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