Background: Associated co-morbidities with psoriasis are treated with concomitant
medications apart from the antipsoriatic therapy and the resulting Drug-Drug Interactions (DDI) may
affect therapeutic outcome.
Objective: To assess the DDI in psoriatic patients with co-morbidities.
Method: In this prospective observational analysis, 150 prescriptions of psoriatic patients, receiving
two or more drugs were analysed using drug interaction checker software. DDI was classified into
minor, moderate, major and pharmacokinetic & pharmacodynamic.
Result: Of 150 patients, 77.3% (n=116) had cardiovascular comorbities; diabetes mellitus (49.3%), psoriatic arthritis
(20.7%), hyperlipidemia (46%), infections (28.7%), neurologic conditions (24.7%) and dermatologic conditions (37.3%)
were other reported comorbidities. Of these, 138 (92%) patients had 612 DDI (4.49 interactions/patient). More number of
interactions were seen in 45-60 yrs (n=311, 50.8%). Moderate DDI (79.9%) were higher; 306 (50%) were
pharmacokinetic interactions. Frequent interactions were due to non-steroidal anti-inflammatory drugs (n=229, 37.4%)
and antibiotics (n=176, 28.8%). Monitoring of the signs & symptoms was the advised intervention in 67.2% of patients.
Mean DDI per patient was more in those who received >10 drugs (9.67). There was an increased number of DDI with an
increase in the number of medications which was statistically significant (p<0.01), with greater number of (n=458, 74.8%)
interactions seen in those who received 5-10 drugs.
Conclusion: There was an increased number of DDI in those who received more number of drugs. Careful monitoring
with appropriate timely laboratory investigations, and a rational drug prescription for the comorbid conditions can prevent
the occurrence of harmful DDIs.