Clonidine
Clonidine is another example of a central sympatholytic agent (similar to Methyldopa) which also works by reducing central sympathetic tone (Lei et al., 2019).
In individuals with hyperadrenergic POTS, this medication has been shown to successfully help stabilize both the blood pressure and heart rate (Lei et al., 2019).
It has been shown to reduce levels of norepinephrine when standing (which are quite elevated in individuals with hyperadrenergic POTS), and peripheral resistance is reduced; both have been shown to help reduce symptoms of orthostatic intolerance in these individuals (Gaffney et al., 1983).
Sources:
Gaffney, F. A., Lane, L. B., Pettinger, W., & Blomqvist, C. J. (1983). Effects of long-term clonidine administration on the hemodynamic and neuroendocrine postural responses of patients with dysautonomia. Chest Journal, 83(2_Supplement), 436. https://doi.org/10.1378/chest.83.2_supplement.436
Lei, L. Y., Chew, D. S., Sheldon, R. S., & Raj, S. R. (2019). Evaluating and managing postural tachycardia syndrome. Cleveland Clinic Journal of Medicine, 86(5), 333–344. https://doi.org/10.3949/ccjm.86a.18002