Situations where great caution should be used as regards opioid use:
    

i.        Respiratory problems: asthma, emphysema

ii.        Decreased blood volume (hypotension)

iii.        Biliary colic

iv.        Liver disease (increased bioavailability)*

v.        Impaired kidney function (accumulation of metabolites)*

vi.        Opioids may aggravate pre-existing convulsions in patients with convulsive disorders. If dosage is escalated substantially above recommended levels (because of tolerance) convulsions may occur in patients who have no previous history

*Opioids may have prolonged duration of action and possibly a cumulative effect in patients who have impaired liver or kidney function.