Part 1: Experiment Studying Drug Interactions

STA 6167 – Project 2

Spring 2008 – Due Feb. 7

Part 1: Experiment studying Drug Interactions

A study was conducted to determine whether there was a drug interaction between popular heartburn medications (pepcid or tagamet) with theophylline (a drug used for respiratory diseases such as COPD and asthma). The researchers selected 14 subjects suffering from chronic obstructive pulmonary disorder (COPD), and had each subject receive each of the following drug combinations (treatments):

·  Theophylline/Placebo (i=1)

·  Theophylline/Tagamet (i=2)

·  Theophylline/Pepcid (i=3)

Under each treatment, the primary measure was the clearance of theophylline (the rate at which the drug is removed from the blood stream, low clearances mean that the drug stays in the body too long and is not good for the patient). Note that in this study the 14 subjects are acting as blocks, and our goal is to compare the true population mean theophylline clearances in the treatment groups.

1)  Give the sample means for each treatment.

2)  Give the sample means for each subject

3)  Obtain the Analysis of Variance Table

4)  Test the null hypothesis that the 3 treatment means are all equal (which implies neither Tagamet or Pepcid interact with theophylline) versus the alternative that the true means are not all equal. (a=0.05)

5)  Use Tukey’s method to compare all pairs of treatment means with an experimentwise error rate of aE=0.05.

6)  Give the relative efficiency of the RBD to CRD for this experiment. How many subjects would be needed per treatment for CRD to give treatment means estimates with the precision of this RBD?

7)  Qualitatively, what is the study’s implications?

Part 2: Experiment studying Recombinant Bovine Growth Hormone (rbGH)

A study involved randomly assigning 30 male and 30 female rats to one of the following 6 treatments (dosing regimens of rbGH):

·  Control (0 mg/kg/day)

·  Subcutaneous Injection (1.0 mg/kg/day)

·  Oral Glavage (0.1 mg/kg/day)

·  Oral Glavage (0.5 mg/kg/day)

·  Oral Glavage (5 mg/kg/day)

·  Oral Glavage (50 mg/kg/day)

The response is 85 day weight gains in the rats.

Analyze this as a 2-Factor ANOVA (gender and dosing regimen).

1)  Give the sample means for the 12 treatments (2 Gender x 6 Dosing Regimens)

2)  Test whether there is an interaction between Gender and Dosing Regimen. (a=0.05)

3)  If there is an interaction, separately for each gender, Use Tukey’s method to compare (aE=0.05) all pairs of dosing. You will need to compute this part by hand using your ANOVA output.

4)  If there is not an interaction:

a)  Test whether there are gender or dosing regimen main effects. (Each at a=0.05).

b)  Use Tukey’s method to compare genders (aE=0.05), and all pairs of dosing regimens (aE=0.05).

5) Qualitatively, what is the study’s implications?