Hepatic Dysfunction

The liver represents the main organ that rids the body from the indigenous metabolic waste as well as exogenous substance introduced to the human body. Recent decades witness the identification of about 60 liver enzymes that are responsible for most of the so-called phase-I metabolism. The clearance of more than 75% of drugs administered to the human body is determined by the activity of these enzymes. In situations where such activity is affected by liver disease, dosing regimen must be modified to ensure that drugs plasma levels remain within safe and effective ranges.

High-Pugh score (CPS) is used as a measure of the decline in the activity or capacity of the liver enzymes to eliminate drugs from the body. Hence, user must provide a measured CPS, or details of such score so that the system estimates it. In either of the above cases, the main concern for the system will be the estimation of the change on overall value of \(K\). This could be achieved by splitting the overall value of \(K\) to its representative components, i.e, \(K_r\) and \(K_h\) according to the percent of drug eliminated by either organ \(Q_0\).

Example: A dose of 1 mg/kg (body weight) is given to a patient every 8 hours

Patient’s specifics (data entry): Age (52 yr), Weight (75 kg), \(S_{cr}\) (2.4 mg/dL)

Hereunder is the solution for estimating the \(Cl_{cr}\) for this patient: $$Cl_{cr}=\frac{(140-52)\times (75)}{72 \times (2.4)}=38.19(mL/min)$$ This means the kidneys have lost 61.8% of its capacity or \(K_r\) has decreased by 61.8%. Hence, if \(Q_0\) is 0.00 (i.e. the drug is completely eliminated by the kidneys), the dose has to be reduced by this ratio. One may recall that \(K = K_r + K_{nr}\). Hence, if \(Q_0\) is 0.5, the decrease in the overall \(K\) will be 30.9%. The same applies if the liver has lost part of its capacity.

Child Pugh Score

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