1. Experiment 2: Factors Affecting Drug Action
A. INFLUENCE OF ROUTE OF ADMINISTRATION
2A – Med
Subsection A2
Anacta, Klarizza
Aquino, Unica
Andal, Charlotte Ann
Aramburo, Jan Christian
Ang, Jessy
Arcilla, Juan Martin
Ang, Joanne Marie
Argana, Desiree
Ang, Kevin Francis
Aribon, Pamela Ann
Ang, Kimberly
Arquiza, Paula
Aningalan, Arvin
Asuncion, Gewelene
Antonio, Abigaille Ann
Atienza, Vyron
Aquende, Hershe
Austria, Mary Martha
Aquino, Arnold Cedric

2. Objectives General Objectives
To determine how the route of administration influences the action of ketamine hydrochloride

3. Objectives Specific Objectives
To determine the latency (sec) and duration of effect (sec) of ketamine hydrochloride when administered intravenously and intramuscularly
To statistically determine if there is a significant difference between the (a) latencies and (b) durations of effect of ketamine hydrochloride in the IV and IM group
To determine the effect of route of administration in the absorption and efficacy of ketamine hydrochloride

4. Definition of terms:
Latency/Time to Peak Effect - Time between initial administration and onset of the maximum expected effect.
Duration of Effect - Length of time peak effect can be expected to last after a single administration of an anesthetic dose.
Righting reflex - A reflex resulting in the body or a body segment tending to regain its former body position when it is displaced.
ESSENTIALS FOR ANIMAL RESEARCH: A PRIMER FOR RESEARCH PERSONNEL
Second Edition
Marilyn J. Brown, D.V.M., M.S

5. METHODOLOGY

6. Ketamine hydrochloride
Preparation : 50mg/mL
Dosage : 5mg/Kg
2-(O-chlorophenyl)-2-(methylamino) cyclohexanone hydrochloride

7. Ketamine hydrochloride
water-soluble
white crystalline
pKa=7.5
commercially available pharmaceutical form is in aqueous solution

8. 2-(2-chlorophenyl)-2-(methylamino)-cyclohexanone
Ketamine
2-(2-chlorophenyl)-2-(methylamino)-cyclohexanone

9. Ketamine anesthetic drug
blocks the N-methyl-D-aspartate (NMDA) glutamate receptor = non- competitive NMDA-receptor antagonist
inhibits activation of NMDA receptor by glutamate
reduces presynaptic release of glutamate
potentiates effects of GABA

10. Experimental Animal: Rabbit1 4 2 3 1 4 2 3
SECTION A
SECTION B 1 4 2 3 1 4 2 3
SECTION C
SECTION D

11. Weighing

12. Dosage
Dosage of drug =(weight of rabbit)(5mg/kg)(1mL/50mg) e.g.: (1.5kg)(5mg/kg)(1mL/50mg) = 0.15mL

13. Intramuscularly (IM) 1 3

14. Intravenously (IV) 2 4

15. Time of injection
Time the righting reflex was lost
Time the righting reflex was regained

16. Righting reflex “static reflex”
bring the body into normal position in space
resist forces acting to displace the body out of normal position
turns a falling animal's body in space so that its paws or feet are pointed at the ground; hence, returns the animal to sternal recumbency after being placed on its back or side

17. Rabbit with no righting reflex

18. RESULTS and DISCUSSION

19. Tabulation of results- Route of Administration
SECTION
Latency
Duration of Effect
Intramuscular
(seconds)
Intravenous A 1
335 11
472
876 2
129 10
322
1112 B 3
170 31
172
371 4
217 30
147
361 C 5 76 7
852
995 6
150 9
517
1357 D
232
906
880 8
193
898
662
Mean
187.75 14
535.75
826.75 SD
Variance
93.75

20. Actual Results

21. Actual Results

22. Actual Results Latency (Mean) Duration (Mean) Intravenous = 14 seconds
Intramuscular = seconds
Duration (Mean)
Intravenous = seconds
Intramuscular = seconds

23. Hypothesis
Ho: there is no significant difference in the latency/duration between intramuscular and intravenous administration
H1: there is significant difference in the latency/duration between intramuscular and intravenous administration

24. Formula for calculating independent t statistics
Test statistic
Its value is used to decide whether or not the null hypothesis should be rejected in our hypothesis test
= difference between population means
= Pooled standard deviation

25. Latency = √ 5275.44(8-1) + 93.75(8-1) t = (187.75 – 14) – 0
Count
mean
variance
Standard deviation
Intramuscular 8
187.75
72.63
Intravenous 14
93.75
9.68
= √ (8-1) (8-1) √
= 51.81
t = ( – 14) – 0
√1/8+1/8
= 7.00

26. Critical region
Set of values of the test statistic for which the null hypothesis is rejected in a hypothesis test
df = n1+n2 -2
df = 14
Critical region =

27. t = 7.00
Critical region = 1.76
Reject Ho
Fail to reject Ho
1.76
7.00

28. Duration
Count
mean
variance
Standard deviation
Intramuscular 8
535.75
296.20
Intravenous
826.75
325.55
Sp= √ (8-1) (8-1)
8+8-2
Sp =311.22
t = ( – ) – 0
311.22√1/8+1/8
= -2.64

29. Duration t = -2.64 Critical region : 1.7613 Reject Ho
Fail to reject Ho
1.76

30. Actual Results: Statistics
Student t test
t test for two independent variables
Significance level = 0.05
Latency
Intramuscular vs Intravenous
P value < 0.05
There is significant difference
Duration
P value > 0.05
There is no significant difference

31. Expected results IV route has faster onset of action than IM route
Duration of action is greater in IM than the IV route

32. Intravenous Drug Administration
Intravenous (IV) [drug administered directly into the bloodstream]
Avoids first pass metabolism
Rapid and complete absorption
[100% Bioavailability]
Fastest rate of drug delivery and onset of action

33. Intravenous Drug Administration
Maximal degree of control over drug circulating levels
No way to stop response to drug
(no recall)

34. Intramuscular Drug Administration
Intramuscular (IM)
- Rapid absorption and onset of action
Uptake of drug dependent on blood flow at the injection site and solubility of the drug.

35. IV versus IM Drug Administration
Onset of action is indeed faster in the IV route.

36. DURATION OF ACTION

37. Sources of Error Human Error:
The administration of drug was done by different experimenter
The time of observation of latency and duration was done by different people

38. CONCLUSION

39. Onset of action IV route has faster onset of action than IM route
The onset of action is dependent on the route of administration

40. Duration of action
Duration of action in the intramuscular route is dependent on the solubility of the drug
The IM route has a longer duration of action than the IV route

41. References
Howland, Richard and Mycek, Mary. Lippincott's Illustrated Reviews. Lippincott Williams and Wilkins,
Katzung, Betram G. Basic and Clinical Pharmacology, 10th ed. The McGraw-Hill Companies, Inc, 2007.

42. THANK YOU!

43. Tolerance Repeated use of ketamine
users can develop a tolerance and/or dependence to the drug.
Rises quickly with regular use and lasts about three days
Can be very high and develop rapidly to the point where after a period of time users will no longer experience the dissociative effects they first began using
Chronic use can cause development of a very high, almost permanent, tolerance to the drug.

44. Ketamine Absorption
Ketamine is rapidly absorbed when administered through the intramuscular (Tmax 5-15 min), nasal (Tmax 20 min) or oral route (as a solution) (Tmax 30 min).
Bioavailability is low when ketamine is given orally (17%) or rectally (25%). Extensive first pass metabolism in liver and intestine is largely responsible for this effect. Bioavailability after nasal administration is approximately 50% (Malinovsky et al., 1996)

45. Ketamine Distribution
Ketamine has a high lipid solubility and low plasma protein binding (12%), which facilitates rapid transfer across the blood- brain barrier.
Initially it is distributed to highly perfused tissues, including the brain, to achieve levels 4-5 times those in plasma (distribution half-life after i.v. 24 sec.).
CNS effects subside, following redistribution to less well-perfused tissues (re-distribution half-life 2.7 min.).

46. Ketamine Metabolism
Biotransformation primarily takes place in the liver. The most important pathway is N-demethylation to norketamine. When administered orally or rectally, initial plasma norketamine concentrations are higher than those of ketamine are, but the plasma area under the curve (AUC) for norketamine is similar for all routes of administration. Norketamine has one-third the anaesthetic potency of ketamine and has analgesic properties. Norketamine may be metabolised through multiple pathways, but the majority is hydroxylated and subsequently conjugated.

47. Ketamine Elimination
The predominant route of elimination is by liver metabolism. The high extraction rate (0.9) makes ketamine clearance susceptible to factors affecting blood flow. The conjugated hydroxy metabolites are mainly excreted renally. Terminal elimination half-lifes are ranging from minutes.