
Pear vodka is a flavored vodka — a neutral base with pear added, so pear is the dominant note.
Pear brandy / eau-de-vie (Poire Williams)
Works in the same amount. It is a little stronger and tastes far more of real pear.
Pear liqueur
Mix it half and half with plain vodka. That gives noticeably more sugar, so cut any syrup by roughly a barspoon per 45 ml.
At 38 to 40% the spirit itself is stable; the pear flavor is what fades. Keep it cold and closed, and finish an opened bottle within months.