Background: Paclitaxel has been used widely for various solid tumors such as ovarian, lung and breast cancers. Patients treated with paclitaxel often experience mild to moderate hypersensitivity reactions (HSR) which usually occur at the first or second dose of paclitaxel. Giving premedication regimens consisting of corticosteroid, H1 and H2 antagonists can reduce the incidence of HSR from paclitaxel, but even when premedication is used, HSR can still occur.
Objective: To find the incidence of hypersensitivity reactions (HSR) from paclitaxel, including characteristics and severity of
paclitaxel-associated hypersensitivity reaction and the effects of premedication regimens used in preventing HSR.
Material and Method: Data of patients who received paclitaxel between January 2014 and December 2015 at Rajavithi Hospital were collected from hospital computer databases, pharmacy databases and chemotherapy unit. Patients who received antidotes for paclitaxel HSR were confirmed as having paclitaxel-induced HSR by medical record review. Reports of HSR from adverse drug reactions and risk management units were also included. The severity of HSR was determined in accordance with NCI CTCAE v4.03. All grade 1 or 2 types were classified as mild-moderate HSR, while severe HSR was defined as grade >3.
Results: A total of 1,132 patients received paclitaxel 5,152 times, and 48 patients (4.24%) 70 times were found to have HSR resulting from the use of paclitaxel. The severity was mostly grade 2 (55 times). Only one patient had grade 4 and did not continue paclitaxel. The first episode of HSR occurred most frequently at the first (17 patients) and second (26 patients) cycle. Premedication used in this study was divided into 2 groups: Group 1, premedication (oral dexamethasone) was given 6 to 24 hours before paclitaxel; and Group 2, premedication (iv dexamethasone) was given 30 minutes before paclitaxel. In the HSR group, HSR occurred 29.17% (14 from 48 patients, 20 times) in group 1 and 70.83% (34 from 48 patients, 50 times) in group 2. Agricultural patients had a higher incidence of HSR (OR 2.55, 95% CI: 1.20 to 5.43). Lung (14 from 187) and cervical (9 from 141) cancer patients had a higher risk of HSR than other cancer sufferers.
Conclusion: The incidence of HSR found in the present research was similar to the results of previous studies in relation to severe HSR. Agricultural workers had a higher risk of HSR, while a premedication regimen of oral dexamethasone 6 to 24 hour before paclitaxel resulted in a lower incidence of HSR. However, the HSR found in both groups was not severe and most patients were able to continue taking paclitaxel.

Keywords: Hypersensitivity reactions, Paclitaxel, Premedication