wˌaɪl ɹˈɪtənˌævɪɹ ɪz ɐ pɹˈoʊɾeɪs ɪnhˈɪbɪɾɚ, ɪt kænˈɑːt biː jˈuːzd tʊ ɪnhˈɪbɪt ˌeɪtʃˌaɪvˈiː sɪɡnˈɪfɪkəntli baɪ ɪtsˈɛlf æt ðə lˈoʊ dˈoʊsᵻz ɹᵻkwˈaɪɚd tʊ ɛnhˈæns ˈʌðɚ pɹˈoʊɾeɪs ɪnhˈɪbɪɾɚz.
While ritonavir is a protease inhibitor, it cannot be used to inhibit HIV significantly by itself at the low doses required to enhance other protease inhibitors.