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Therapuetic Drug Monitoring Of Aminoglycoside

THERAPUETIC DRUG MONITORING
OF AMINOGLYCOSIDE

CASE STUDY:
A 74 year old 60 kg man is commenced on Gentamycin I/V in a dose of 80 mg every 8hr .However his serum creatinine is raised at 220umol and doctor is worried about toxicity.pharmacit is asked for advise.
HINTS:
• Calculate Vd and Cl
• Predict peak and trough level( Cmax and Cmin)
• Putting desired levels calculate interval.
SOLUTION:
Vd from population data = 0.3L
For 60 kg = 0.3*60
= 18 L

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Though value is too high, so pharmacist advise to reduce trough level.So,dosing interval is changed.
Cp(desired) = Cp(observed) e-kt
LogCp = logCp-kt/2.303
= log5.6 –0.07t/2.303
=0.748-0.030t
0.03t = 0.748
t =0.748/0.030
= 24 hrs