Margaret A.WinklerMDIndividualAuthorPhil B.FontanarosaMD, Senior EditorsIndividualAuthor
Copyright 1999 American Medical Association.
All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.1999
To the Editor: The Editorial
regarding HIV treatment by Dr Gulick1 states that "the
clinician has access to a total of 13 antiretroviral agents approved by
the Food and Drug Administration, with a theoretical 1716 triple
combinations from which to choose." The number 1716 represents the
number of permutations of 3 of the 13 agents (13 × 12 × 11). There
are 286 combinations of 3 of the 13 agents: (13 × 12 × 11)/(3 × 2
× 1). The number of permutations reflects the number of therapeutic
options only if the order in which the drugs is given is of importance.
Since all drugs are given simultaneously, the correct number of
theoretical options is 286, which is still a formidable challenge for
Weinstein B. Nevirapine, Didanosine, and Zidovudine for Patients With HIV: The INCAS Trial. JAMA. 1999;281(2):130-131. doi:10-1001/pubs.JAMA-ISSN-0098-7484-281-2-jac80019