Factors affecting drug adherence

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Transcript Factors affecting drug adherence

Ethnopharmacology
by Sue Henderson
Ethnopharmacology
• Study of the effect of
ethnicity on
responses to
prescribed medication
and incorporates
pharmacogenetics,
the study of genetic
variations in
responses to drugs.
Ethnicity: Shared cultural bonds,
common genetic heritage or both
Race
Common
lineage and
geographic
origin of
ancestry
(genetics)
Culture
Common
learned
beliefs and
customs
Effects of ethnicity on drug
response
• Pharmacokinetics (drugs absorption,
metabolism, distribution, and elimination)
• Pharmacodynamics (drugs mechanism of
action and effects at the target site)
• Consumer adherence and education
• Wide variation in drug response within
each ethnic group
Cultural competence involves:
• Working within the consumers cultural
context
Knowledge of consumers:
• Beliefs/values about health/illness
• Responses to treatment, including drug
therapies.
Assessment
• “What do you think caused your health
problem?”
• “What treatment do you think will help
you?”
Metabolism of drugs
• Most drugs metabolized by liver enzymes.
• Cytochrome P-450 (CYP) is a common
group of liver enzymes
• Rate of metabolism will affect drug blood
levels
• Genetic abnormalities in enzymes
common
• Enzymes vary by race/ethnic group
Genetic abnormalities
Ultrarapid metabolizers
• > 2 functional copies of CYP2D6 gene
faster than normal enzyme activity = lower
levels of drug in blood
Poor metabolizers
• 2 non-functional copies of CYP2D6 gene
slower than normal enzyme activity =
higher level of drug in blood
Asians: Antipsychotics
Asians same dose as whites:
• Higher blood levels of typical
antipsychotics
• Have more EPSE
• Need lower doses
(Atypicals may be better but few ethnopharmacologic studies on atypicals)
Tricyclic antidepressants
Asians compared whites have:
• Faster therapeutic response
• Higher blood levels drug
• More adverse effects (such as delirium)
• Adverse effects occur at much lower
dosages.
(Few ethno-pharmacologic studies on
SSRIs)
Non White: Lithium
• Require lower doses
• Report more lethargy and dizziness (even
when blood levels similar).
• Monitor closely for symptoms of toxicity
(blood levels may be higher than in white’s
given same dosage).
Cultural/Lifestyle
• Tobacco/alcohol use (influenced by
cultural & genetic factors) affect drug
response.
• Tobacco/alcohol increase or decrease rate
of drug metabolizm & drug clearance.
• Smoking decreases blood levels of typical
antipsychotics (? caused by effects of
smoking on liver enzymes).
Adherence
• Adverse effects contribute to non-adherence.
• Drug effects may be interpreted as negative or
positive depending on the consumers
beliefs/expectations.
Factors affecting drug adherence:
• Language barriers
• Clinicians’ beliefs/preconceptions
• Consumers distrust of the health care system
References
Muñoz, C., & Hilgenberg, C. (2005).
Ethnopharmacology American Journal of
Nursing, 105(8), 40 - 48.