Changing HIV drugs

Some symptoms in the first few weeks of treatment may be caused by immune stimulation of your body getting better. Treatment sometimes takes a while to settle down. So what you think may be side effects may not be related to the drugs at all.

Many symptoms then become easier over the first few days and weeks of treatment.

If your initial symptoms are only mild or moderate, seeing whether they settle down before changing treatment, can be good advice.

If side effects are more serious or difficult it is sometimes important to switch drugs.

If you can’t tolerate one treatment, then changing to another at any time is usually easy. It will not affect your future options.

• Switching drugs can improve your quality of life and still keep your viral load undetectable.
• Never just stop or interrupt treatment without contacting your doctor first.

The decision to change treatment in order to manage side effects will depend on:

• The other drugs available.
• Whether the side effects are likely to get worse if you remain on the same drugs.
• Whether the side effects are related to drugs. Even though there may not be a known link, this may be a new report, and you may be the first person to experience this.
• If you have a detectable viral load before switching then have a resistance test first.
• If your current combination is not your first treatment, you may have fewer options,

Close monitoring after changing a drug will help you know whether the treatment that you switched from was causing those symptoms.

Changing only one or two drugs is only recommended when viral load is undetectable prior to the switch.

Switching nukes

Most combinations involve two nukes: AZT, d4T, ddI, 3TC, FTC, abacavir, or tenofovir.

In general, people still using AZT, d4T or ddI should switch to tenofovir or abacavir as these drugs have fewer side effects.

So long as you haven’t developed resistance to other nukes, you can switch between them. The exceptions are:

• Do not use 3TC and FTC together
• Do not use AZT and d4T together
• Do not use d4T and ddI together
• Do not use ddI and tenofovir together
• There may be a caution against using abacavir and tenofovir together

Switching NNRTIs

Nevirapine and efavirenz have similar potency but some different side effects.

Nevirapine is more linked with skin rash and liver toxicity – usually in the first 1-2 months of treatment.

Efavirenz is linked to mood disturbance, disturbed sleep patterns and vivid dreams (called CNS side effects) when starting and more rarely in the long term.

You should be able to switch from one to the other without stopping treatment or changing your other drugs.

Two newer NNRTIs may also become more widely used as options for people who have difficulty with efavirenz or nevirapine.

Etravirine (Intelence, TMC-125) is a new NNRTI that can be used if you have difficulty with nevirapine or efavirenz, Etravirine does not cause CNS side effects.

Rilpivirine (TMC-278) is a new NNRTI that is expected in 2011. Although it still has CNS side effects, this is only at half the rate compared to efavirenz.

Switching between PIs

Switching from one protease inhibitor (PI) to another is also straight-forward, especially if both PIs are being boosted by 100 mg or 200 mg of ritonavir.

However, some people find ritonavir a difficult drug, even at 100 mg/day.

Although not generally recommended, atazanavir and fosamprenavir can also be used without ritonavir.

If you want to do this, your drug levels need to be checked using TDM tests.

Using new drugs and new classes of drugs

One of the advantages of new drugs is that they hopefully have fewer side effects.

There are several new drugs available including some that work in different ways.

These include:

• raltegravir (an integrase inhibitor),
• maraviroc (a CCR5 inhibitor),
• etravirine (an NNRTI), and
• darunavir/r (a protease inhibitor).

Each of these drugs may have a different role as switch options based on their side effects.

For example, raltegravir does not increase cholesterol or triglycerides.

Many of these drugs could also be used as a switch option for people who are currently having trouble with T-20.

Darunavir uses a lower boosting dose of ritonavir than some other protease inhibitors.

As each new drug becomes more widely used, they will probably be used as switch options.

Each choice will be based on your individual treatment history.It may also depend on how the drug is licensed, on drug cost, and on which clinic you attend. If it is important to get access to a new drug, it may be worth changing your clinic.