Drug causing side effect

Alternative drug

Cautions

Nucleoside /

Nucleotide

AZT, 3TC, d4T, ddI, abacavir,

Another nucleoside

Cross-resistance between nucleosides. AZT & d4T or 3TC & ddC shouldn’t be used in the same combination.

(ddC is rarely used), tenofivir (nucleotide)

PI or dual PI * or NNRTI

Will depend on previous treatment and current combination. Nucleoside sparing combinations may be important if there are severe side effects.

NNRTI

Efavirenz or nevirapine

Another NNRTI

PI or dual PI * or  boosted PI **

Previous PI use will determine choice of next PI.

abacavir

There is limited data on long term effects of triple nucleoside combinations.

Protease

Inhibitors (PI)

Any single PI

New PI

Switching some single PIs can lead to a higher risk of viral rebounding. Switching from indinavir to nelfinavir reported a higher risk of rebound – but switching from nelfinavir to indinavir did not.

Dual PI *Boosted PI **

Switching from a single to dual PI combination generally increases potency against HIV. TDM should be used to check drug levels and toxicity.

NNRTI

Generally NNRTIs are easier for tolerance and adherence. If several nucleosides have been used previously, the risk of a viral load rebound is slightly higher

abacavir

Similar caution to switching to NNRTI. Limited long term data on triple nucleoside combinations.

Dual */booster ** PI

Changing dose

Confirm dosing with TDM

New dual */booster PI **

Confirm dosing with TDM

NNRTI

Generally NNRTIs are easier to take and tolerate. If several nucleosides have been used previously, the risk of a viral load rebound is slightly higher.