Drug Information Resources

Published on 16/06/2015 by admin

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CHAPTER 4 Drug Information Resources

The pharmacist is the healthcare professional who is the point-person for all drug information. Because it is impossible for any one person to know everything, the pharmacist should be able to know where to get information. In addition to locating the information, the pharmacist must be able to interpret, evaluate, and apply it. Equally important is communication of this information. If a physician asks for information, the pharmacist can likely share the information with the language in which it was discovered. However, if the information is intended to be passed along to a patient, the pharmacist may need to explain it in a way that reflects the patient’s health literacy (explained in further detail in Chapter 6, Patient Education).

I. Hierarchy of Pharmacy and Medical Literature

II. Components of a Clinical Trial

B. Baseline assessment

C. Study location

1. Single center: use of one site to conduct a research study

2. Multicenter: use of multiple sites to conduct a research study

3. International: use of multiple countries to conduct a research study

1. Single blind: patient masked, or investigator masked, but not both

2. Double blind: patient and investigator masked

3. Open label: no masking; all patients and investigators aware of treatment

1. Placebo controlled: administration of an inactive substance for a control

2. Double dummy: use of multiple controls to maintain blinding

a) Example: To compare two medicines, one presented as blue tablets and one as red capsules, researchers could also supply blue placebo tablets and red placebo capsules so that both groups of patients would take one blue tablet and one red capsule

3. Active control: use of an established therapy as the comparative group

4. Crossover: patients serve as their own control by receiving multiple interventions

G. Institutional review board (IRB), ethics committees

H. Intervention, duration of treatment

1. Measure of adherence

L. Outcome Measures

1. Primary/secondary endpoints

2. Surrogate endpoints: easily measured substitute markers in place of more clinically meaningful endpoints (e.g., CD4 count used as a surrogate endpoint for a trial regarding HIV infection)

1. Goal: to be confident that the probability statement (p value) is valid and to maximize the possibility of detecting a difference when one actually exists¹

O. Reporting adverse effects (MedWatch)

III. Assessing Trial Results

B. Were the findings statistically significant?

1. Hypothesis testing

a) Tests against the null hypothesis

(1) Null hypothesis (H_o): states that the variable of interest is equal to a given value or that no relationship exists between various variables

2. Statistical and clinical significance

a) Statistical: probability that the results are due to chance or due to a true effect of treatment

b) Clinical: importance of the practical relevance or variation of a difference in outcomes

(1) A statistically significant outcome may not be clinically significant

a) The probability of the observed result or a more extreme result occurring by chance alone

b) The probability of the observed difference occurring if the null hypothesis is true

5. Confidence interval (CI)

a) The range of values in which researchers can be certain that the true point estimate will fall

b) 95% CI most commonly reported

(1) 95% probability that the true result lies within the range of results found, and there is a 5% probability that the true range lies outside the interval

c) CI is calculated by subtracting from and adding to the sample mean the appropriate number of standard errors of the mean

d) The narrower the CI, the greater the reliability and more precise the data

C. How large is the treatment effect (when the primary outcome shows a statistically significant difference)?

1. Relative risk (RR)

a) The reduction in the risk from one therapy relative to another (RR = events in treatment group ÷ events in placebo group)

(1) A RR of 1 means that there is no difference.

(2) A RR that is <1 (e.g., 0.75) means that risk is decreased

(3) A RR that is >1 (e.g., 1.15) means that risk is increased

b) Commonly used to express the therapeutic benefit of a drug

2. Absolute reduction risk (ARR)

a) The absolute difference between the probabilities of the treatment event rate and control event rate (ARR = Probability of events in placebo group [P_B] − Probability of events in the active treatment group [P_A])

b) Expressed as a percentage

3. Number needed to treat (NNT)

a) Number of subjects needed to treat over a defined period of time to experience one benefit of therapy

V. Study Types in Clinical Research

A. Randomized controlled trial

1. An experiment in which investigators assign, by random allocation, eligible subjects into intervention groups to receive or not to receive one or more interventions that are being compared

2. Gold standard: Randomized controlled trials are considered to have the highest validity and reliability of various research designs, as they eliminate causes of bias and provide a high level of experimental control.

3. Necessary for Food and Drug Administration (FDA) approval

B. Cohort studies

1. Group of subjects who have not yet experienced the outcome of interest

2. Subjects exposed to a factor of interest are compared to a group not exposed and followed prospectively over time

C. Case-control studies

1. Subjects with a particular characteristic are compared to a similar group without the characteristic to determine the cause

2. Retrospective

D. Case reports

2. No designed intervention

3. Descriptive account of a subject

E. Meta-analysis

1. A method of combining results of previous and similar research to determine a single estimate of treatment

F. Cross-sectional studies

1. Measurements taken at a single point in time

1. Research used to study the incidence, distribution, and relationship

H. “N-of-1” trials

1. Randomized controlled study involving a single subject

2. Crossover design

3. Lack of generalizability to a population

VI. Research involved in the FDA Drug Approval Process

A. Preclinical research

1. Goal: assess potential therapeutic effects

2. Does not predict human response

1. Initial study, usually in healthy human volunteers

2. Small number of subjects (fewer than 100 subjects); brief length of study (less than 1 year

3. Determines toxicology, metabolism, and pharmacologic activities; early evidence of effectiveness

1. Expanded drug study to obtain preliminary efficacy data and safety in humans

2. Small and highly homogeneous population of patients for whom the drug is intended (N = several hundred participants)

1. Pivotal trials

2. Larger study (N = hundreds to thousands of participants)

3. Long-term (up to several years)

4. Semidiverse population (representing target population)

5. Establishes final formulation, marketing claims, product stability, packaging, and storage concerns

6. Successful completion may mean ready to submit compound to FDA for approval

E. Phase IV (postmarketing surveillance)

F. New Drug Application (NDA) form

G. Abbreviated NDA (aNDA) form: generic drug approval

H. Supplemental NDA (sNDA): approval for new indication

Table 4-1 Common Examples of Tertiary Literature (NOTE: lists are not comprehensive)

Topic of Interest	Literature in which to Find Topic
Alcohol/sugar/gluten free	Red Book (Drug Topics)
Adverse effects	Meyler’s Side Effects of Drugs Drug-Induced Diseases
Bioequivalence	Orange Book (electronic version on FDA website)
Compounding	Remington’s Pharmaceutical Sciences Extemporaneous Formulations
Consumer health information	USP DI Vol II: Advice for the Patient (obsolete) Clinical Pharmacology Lexi-Comp Micromedex Websites: www.drugdigest.org www.webmd.com
Diseases/General Medicine	Cecil Textbook of Medicine Harrison’s Principles of Internal Medicine
Dosing Dosing: Special populations	AHFS Drug Information Clinical Pharmacology Buy Membership for Basic Science Category to continue reading. Learn more here

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