Reasons for failure to improve with therapy:
(1) diagnosis-related
(2) medication-related
(3) patient-related
Diagnosis-related:
(1) wrong diagnosis
(2) presence of more than 1 condition (mixed)
(2a) initially
(2b) during therapy
(3) adverse drug reaction
(4) correct diagnosis but with disease progression or relapse
(5) re-exposure following cure
Medication-related:
(1) inappropriate drug (wrong choice, or more effective drug available)
(2) resistance factor to effect (patient genetics, micro-organism, tumor-related, absence of necessary cofactor)
(3) insufficient dose
(4) inappropriate route of administration
(5) antagonism from another drug
(6) surgery or other therapy required for effect (medication alone ineffective)
(7) insufficient duration of therapy (need to wait for the effect)
(8) counterfeit or bogus drug
Patient-related:
(1) noncompliance
(2) decreased absorption
(3) increased metabolism or excretion
(4) malingering or intentionally misleading
(5) failure to comprehend or follow instructions
(6) comorbid condition that has impaired the host response
