There are five classes of antiretroviral in use at present: NRTIs, non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), integrase strand transfer inhibitors (INSTIs), and entry inhibitors
. Agents which target the viral capsid and maturation process are under investigation.
A large number of drug-resistant HIV variants have been previously reported, and they are known to be resistant to various drug groups such as nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors, integrase inhibitors, and entry inhibitors
Researches such as  suggest that viruses blocked by entry inhibitors
such as the fusion inhibitors are likely redistributed to plasma, where they artificially increase the number of HIV virions.
The bNAbs and HIV entry inhibitors
or inactivators are the best candidates.
Since hepatitis Delta virus uses the same receptor as HBV, HBV entry inhibitors
are equally effective against both viruses .
The five classes of drugs used for the management of HIV are entry inhibitors
, fusion inhibitors, integrase inhibitors, protease inhibitors and reverse transcriptase inhibitors (nucleoside reverse transcriptase inhibitors and non-nucleoside reverse transcriptase inhibitors).
The antiretroviral classes new in the mid-1990s--protease inhibitors and nonnucleosides--were not joined by entry inhibitors
and integrase inhibitors until 2003 and 2007.
Maglich et al., "The relative activity of "function sparing" HIV-1 entry inhibitors
on viral entry and CCR5 internalization: is allosteric functional selectivity a valuable therapeutic property?" Molecular Pharmacology, vol.
T-20 is one of the entry inhibitors
which are approved by FDA.
 There are very few data on the entry inhibitors
and integrase inhibitors, although some early data indicate the possibility of an improved metabolic and lipid profile.
Several anti-HIV inhibitors have been identified in PG juice and are believed to be candidates for topical microbicides as well as an HIV-I entry inhibitors
(Neurath et al.
"In order to efficiently block intracellular fusion events, the next generation of HIV entry inhibitors
must be able to permeate the cell membrane," he added.