A patient weighing 73 kg received a 250 mg dose of drug via an IV injection. Blood samples were taken from the patient at regular intervals and the drug plasma concentration was determined for each sample (see the table below).
Time (hr) |
Cp(mg/L) |
0.25 |
11.6 |
0.5 |
8.4 |
0.75 |
7.2 |
1.00 |
6.1 |
1.50 |
4.2 |
2.00 |
3.2 |
3.00 |
1.9 |
4.00 |
1.0 |
5.00 |
0.3 |
Plot the data and determine the elimination rate constant for this drug.
Rate = = 5.571 mg/L/hr
Half of Cp = =
Half – life = time take for formation of 5.8 mg/L
From the graph (light blue line), HALF – LIFE = 1.1 hrs
Conversation of 10 10 μg/mL to mg/L
= 10 mg/L
From the graph(black line) = 0.4 hours
If the initial dosage was 250 mg the duration taken was 5 hours and elimination from the blood was 11.6 mg/L
Y = 12.826
Doubling dosage will double elimination too
0.3 *2 = 12.826
= 0.04678
= 0.04678
0.698x = 3.0623
X = 4.39 hours
Duration 50% of the drug to be eliminated = half- life = 1.1 hrs
Duration 75% of the drug to be eliminated (green line) = 75% *11.6 mg/L = 8.7 mg/L = 0.5 hours
Duration 75% of the drug to be eliminated (purple line) = 99.9% *11.6 mg/L = 11.5884 mg/L = 0.25 hoursPlot the data and estimate the clearance of the drug using the area under the curve method
Using excel to solve for area under the cover
Time (hr) |
Cp(mg/L) |
Area under the cove |
0.25 |
11.6 |
2.5 |
0.5 |
8.4 |
1.95 |
0.75 |
7.2 |
1.6625 |
1 |
6.1 |
2.575 |
1.5 |
4.2 |
1.85 |
2 |
3.2 |
2.55 |
3 |
1.9 |
1.45 |
4 |
1 |
0.65 |
5 |
0.3 |
|
Total |
15.1875 |
|
15.1875 unit-square
Rate of elimination = 5.571 mg/L/hr
45% = 2.50695 mg/L/hr
2.50695 mg = 1 L/hr
1 mg = 0.34 L/hr
Renal and metabolic clearance = 0.34 L/hr
Q2)
An 80 kg patient is to be given a 1.5 mg/kg body weight dose of gentamicin intravenously over 1 hour every 8 hours. Assume the half-life of gentamicin and volume of distribution in the patient are 2.6 hours and 0.25 L/kg respectively.
Half – life =
ke =
ke = 0.267
Concentration = C = =
= 6.0 mg/L
t =
t =
= 19.5 hours
Peak
Cmax =
1 dose
Cmax =
= 0.204
Cmax =
= 0.408
iii) 5 doses
Cmax =
= 1.02
Cmax= C*max *
Cmax= 6.0 *
= 0.0329 mg/L
No, since the concentration is low as compared to the initial concentration
Cmax= C*max *
Cmax= 6.0 *
= 0.00989 mg/L
Changing of the dosing interval has not affected the steady peak and through plasma concentration, since value achieved is lower
Cmax= C*max *
Half of the dose = 6/2 = 3.0 mg/L
Cmax= 3.0 *
= 0.01644 mg/L
The steady state peak and through plasma concentration decreases by 50%
(g) If the volume of distribution decreases by 50%, what is the change observed in the steady state peak and trough plasma concentrations (providing the dose elimination rate constant, and dosing interval remain the same as in part (a) of the question)?
Concentration = C = =
= 12.0 mg/L
Cmax= C*max *
Cmax= 12.0 *
= 0.0658 mg/L
The steady state peak and through plasma concentration increase by 50%
Q3)
A 70.0 kg patient is given a 2.6 mg/kg dose of a drug by intravenous injection. Blood samples were taken from the patient at regular intervals and the drug plasma concentration was determined for each sample (see the table below).
Time (min) |
Cp(mg/L) |
2 |
93.08 |
7 |
69.11 |
10 |
63.82 |
15 |
54.79 |
20 |
48.73 |
30 |
38.63 |
45 |
27.85 |
60 |
22.92 |
75 |
19.12 |
90 |
13.62 |
105 |
11.43 |
120 |
9.04 |
The pharmacokinetics of the drug displays two-compartment model kinetics. Plot the data for the drug and determine the rate constants for the both distribution phase and the elimination phase.
Distribution phase (upper part) = = 4.33 mg/L/min
Elimination phase (lower part) = = 0.3125 mg/L/min
Distribution phase is the initial steep phase of the cur the dissemination into tissues principally decides the early quick decrease in plasma concentration. With time, distribution equilibrium of medication in tissue with that in plasma is built up in an ever increasing number of tissues, lastly changes in plasma concentration reflect a relative change in the concentration of medication in all tissues and in this manner in the measure of medication in the body. Amid this proportionality stage, the body demonstrations dynamically as a solitary compartment.. Amid this stage, the decay of the plasma concentration is related exclusively with elimination of medication from the body, at the end of the day it compares to the energy of medication end. Along these lines, this stage is frequently called the elimination stage.
(c) Explain why the distribution phase rate constant is greater than the elimination phase rate constant.
It is the steep phase of the curve, since distribution into tissues primarily determines the early rapid decline in plasma concentration
Q4)
Phenytoin is being taken by a patient to control seizures. A daily dose of 300 mg at bedtime results in a steady state plasma concentration of 8 mg/L. When the dose is increased to 400 mg, the steady state plasma concentration changes to 22 mg/L. Assuming Michaelis-Menten kinetics, determine the daily dose that would give a steady state plasma concentration changes of 15 mg/L. Include a plot of the data and the Michaelis-Menten parameters that you used to calculate your answer
R, mg |
Css, mg/L |
R/Css |
300 |
8 |
38 |
400 |
22 |
18 |
Equation
Y = -5x + 490
Y = -5*15 + 490
= 415 mg
Q5)
S = Wa – Wc = (gamma)s – (gamma)l – (gamma)ls
72.9 – 32.5 -15.6 = 24.8 mNm-1
A positive number means that the material will spread
Energy = 6 γ V/d
V = 120/0.8 = 150 ml
Diameter = 0.0025 cm
Work done = 6*52 *150/0.0025
= 18720000
Energy = 6 γ V/d
V = 120/0.8 = 150 ml
Diameter = 0.0025 cm
Work done = 6*24 *150/0.0025
= 8,640,000
(d) Draw the structure of polysorbate 80 and explain why it is more soluble in water at lower temperatures?
Q6)
Requirements
Tablet in fine powder
Gelatin Benzoic acid
Amaranth solution
Chloroform water and raspberry syrup BP
Acacia gum powder
Compound tragacanth powder
Tamarind gum
For preparation of tablet suspensions, polysaccharide powder of about 10 g of tablet were triturated together with a volume of about 20 ml of Raspberry syrup to form a smooth paste. Benzoic acid solution (2 ml) and 1ml of amaranth solution were added gradually with constant stirring and then mixed with 50 ml of chloroform water double strength. The mixture is then transferred into a 100 ml amber bottle, made up to volume with distilled water and then shaken vigorously for about 2 min (thus making 0.5%w/v of the gum in the preparation).
V α d2
The velocity (v) of sedimentation is directly proportional to the square of diameter of particle.
(ρ s – ρo) V α (ρ s – ρo)
V α 1/ ηo The velocity of the sedimentation is inversely proportional to viscosity of dispersion medium. Therefore increasing the viscosity of medium will decrease the settling, therefore the particles will achieve a good dispersion system.
The ormation of net charge on the particle surface will affects the ions in the surrounding interfacial region, this will resulit to increase in conter ionswhich are close o the surface. Therefore their eill be a formstion an electrical layer which will exists around each every particle. Hence the ion that be beyond this boundary will remain in bulk dispersant.
(d) Often, a surfactant is added to a suspension mixture in order to make it easier to re-suspend the solid particles. With the aid of diagrams, describe the mechanisms to explain how this occurs.
Ionic surfactants act by neutralizing the charge on the particles. The surfacant will be absorbed onto more than one particle because of their long structure hence, formation of a loose flocculated structure.
Essay Writing Service Features
Our Experience
No matter how complex your assignment is, we can find the right professional for your specific task. Contact Essay is an essay writing company that hires only the smartest minds to help you with your projects. Our expertise allows us to provide students with high-quality academic writing, editing & proofreading services.Free Features
Free revision policy
$10Free bibliography & reference
$8Free title page
$8Free formatting
$8How Our Essay Writing Service Works
First, you will need to complete an order form. It's not difficult but, in case there is anything you find not to be clear, you may always call us so that we can guide you through it. On the order form, you will need to include some basic information concerning your order: subject, topic, number of pages, etc. We also encourage our clients to upload any relevant information or sources that will help.
Complete the order formOnce we have all the information and instructions that we need, we select the most suitable writer for your assignment. While everything seems to be clear, the writer, who has complete knowledge of the subject, may need clarification from you. It is at that point that you would receive a call or email from us.
Writer’s assignmentAs soon as the writer has finished, it will be delivered both to the website and to your email address so that you will not miss it. If your deadline is close at hand, we will place a call to you to make sure that you receive the paper on time.
Completing the order and download