As you know, you need the page number for citing a resource in APA. When an electronic source lacks numbered pages, you include paragraph numbers or headings to help readers locate the particular passage being cited.
If the source has numbered paragraphs, use the paragraph number preceded by the abbreviation “para.”: (Hall, 2008, para. 5). If the source contains headings, cite the appropriate heading in parentheses; you may also indicate the paragraph under the heading that you are referring to, even if the paragraphs are not numbered.
Hoppin and Taveras (2004) pointed out that several other medications were classified by the Drug Enforcement Administration as having the “potential for abuse” (Weight-Loss Drugs section, para. 6).