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Gravity
Terms in this set (30)
Rate of Elimination =
= Ke x Amount in Body
= Clearance x Cp
Half Life =
= 0.693 x Vd/Clearance
= 0.693/Ke
Amount in Body =
= Cp x Vd
Loading Dose =
= ΔC x Vd
_________________________
F x S
Peak Concentration =
= LD x F x S
__________________
Vd
Volume of Distribution (Vd) =
= Vp + Vt x [Fp/Ft]
• V= volume of distribution
• Vp= plasma volume
• Vt= tissue volume
• Fp= fraction of unbound drug in the plasma
• Ft= fraction of unbound drug in the tissue
Partition Coefficient =
= log([solute in organic]/[solute in water])
Protein Binding (%) =
(Total - Unbound)/Total x 100%
Modified HHB Equation (Weak Acid) =
pH = pKa + log[ionized/unionized]
Modified HHB Equation (Weak Base) =
pH = pKa + log[unionized/ionized]
% Ionized (Weak Acid) =
100
____________________
1 + 10^(pKa-pH)
% Ionized (Weak Base) =
100
____________________
1 + 10^(pH-pKa)
Css =
Dose/Clearance
Extraction Ratio =
CA-CV
__________
CA
Renal Clearance =
= Renal Blood Flow (Q) x Extraction Ratio
= Rate of Elimination/Cp
= Vd x Ke
= d(GFR) + (Rate of TS - Rate of TR)/Cp
• If renal clearance < 1, filtered and reabsorbed
• If renal clearance = 1, filtered 100%
• If renal clearance > 1, filtered and secreted
• Q = 1.2 L/min
Maintenance Dose =
Cpss x Clearance
______________________
F x S
••NOTE: Clearance is constant in 1st order drugs. Therefore, if you double clearance, you will cut Cpss in half. If you half clearance, you will double Cpss.
First Order # Half Lives: % Steady State
1: 50%
2: 75%
3: 88%
4: 94%
5: 97%
E =
= Emax x C
_________________
EC50 + C
Therapeutic Index =
LD50/ED50
Absolute Bioavailability =
AUC PO/AUC IV
Relative Bioavailability =
AUC PO/AUC Standard
Anion Gap =
Na - Cl - HCO3
If > 12, considered AG Acidosis and is due to:
M methanol
U uremia (renal failure)
D DKA (also AKA and starvation)
P paraldehyde
I isoniazid
L lactic acidosis
E ethylene glycol
S salicylates
(+ nitroprusside)
First Order Drug Accumulation =
1
____________
1 - e^-Ket
Osmolality =
2 Na + (Glucose/20) + (BUN/3) + (ETOH/5)
Osmolal Gap =
Given Osmolality - Calculated Osmolality - 10
A normal osmol gap is < 10 mOsm/kg
Concentration from Osmolality =
Osmolar Gap x (Molecular Weight/10)
Zero Order dC/dt
dC/dt = -K
First Order dC/dt
dC/dt = -Ke x C
Michaelis Menten dC/dt
dC/dt = -Vm x C
_______________
Km + C
When C >> Km, dC/dt = -Vm (zero order)
When Km >> C, dC/dt = -Vm/Km x C (first order)
CLsystem =
= CL liver + CL renal + CL other
;