Rubidium (and to a much lesser extent caesium) can function as temporary cures for hypokalemia; while rubidium can adequately physiologically substitute potassium in some systems, caesium is never able to do so.
ɹuːbˈɪdiəm ænd tʊ ɐ mˈʌtʃ lˈɛsɚɹ ɛkstˈɛnt sˈiːsiəm kæn fˈʌŋkʃən æz tˈɛmpɚɹˌɛɹi kjˈʊɹz fɔːɹ hˌaɪpoʊkeɪlˈiːmiə; wˌaɪl ɹuːbˈɪdiəm kæn ˈædɪkwətli fˌɪzɪəlˈɑːdʒɪkli sˈʌbstɪtˌuːt pətˈæsiəm ɪn sˌʌm sˈɪstəmz, sˈiːsiəm ɪz nˈɛvɚɹ ˈeɪbəl tə dˈuː soʊ.