The invention relates to compounds of formula (I) or a pharmaceutically acceptable solvate or salt thereof, including a solvate of such a salt, wherein R
1
is a group such that a compound of formula (I) is a prodrug of 1R,2S-methoxamine that is converted within the kidney tubules into its active form or an active metabolite thereof. The compounds find particular use in the treatment or prophylaxis of urinary incontinence.