Two novel potentiometric sensors were developed for the quantification of olopatadine hydrochloride and oxeladine citrate in pure forms, pharmaceutical preparations and human plasma. The both sensors were fabricated on incorporating the olopatadine and oxeladine tetraphenylborate ion-pairs as electroactive materials in plasticized poly (vinyl chloride) matrix membranes with o-nitrophenyl octyl ether. They displayed Nernstian and near Nernstian responses over the concentration ranges of 1.0 × 10−5–1.0 × 10−2 mol L−1 oxeladine and olopatadine with cationic slopes of 60 and 50 mV decade−1, respectively. Detection limits were reported to be 4.4 × 10−6 and 5.0 × 10−6 mol L−1 while the response times were 3.0 and 18 s for oxeladine and olopatadine, respectively. The useful ranges of pH were 2.5–8.5 and 3.0–4.5 for oxeladine and olopatadine, respectively. The life extents were long (3 months) for both sensors. The sensors were successfully used for the assay of oxeladine and olopatadine in pharmaceutical dosage forms with a recovery of 100.0% for both drugs. Also the oxeladine sensor was used for the estimation of the drug in human plasma with an average recovery of 99.49%.