Delavirdine warnings and precautions

# Warnings

## Drug Interactions
Because delavirdine may inhibit the metabolism of many different drugs (e.g., antiarrhythmics, calcium channel blockers, sedative hypnotics, and others), serious and/or life-threatening drug interactions could result from inappropriate coadministration of some drugs with delavirdine. In addition, some drugs may markedly reduce delavirdine plasma concentrations, resulting in suboptimal antiviral activity and subsequent emergence of drug resistance. All prescribers should become familiar with the following tables in this package insert: Table 5, Drugs That Are Contraindicated With RESCRIPTOR;Table 6, Drugs That Should Not Be Coadministered With RESCRIPTOR;and Table 7, Established and Other Potentially Significant Drug Interactions: Alteration in Dose or Regimen May Be Recommended Based on Drug Interaction Studies or Predicted Interaction. Additional details on drug interactions can be found in Tables 1 and 2 under the CLINICAL PHARMACOLOGY section.
Concomitant use of lovastatin or simvastatin with RESCRIPTOR is not recommended. Caution should be exercised if RESCRIPTOR is used concurrently with other HMG-CoA reductase inhibitors that are also metabolized by the CYP3A4 pathway (e.g., atorvastatin or cerivastatin). The risk of myopathy including rhabdomyolysis may be increased when RESCRIPTOR is used in combination with these drugs.
Particular caution should be used when prescribing sildenafil in patients receiving RESCRIPTOR. Coadministration of sildenafil with RESCRIPTOR is expected to substantially increase sildenafil concentrations and may result in an increase in sildenafil-associated adverse events, including hypotension, visual changes, and priapism (see PRECAUTIONS: Drug Interactions and Information for Patients, and the complete prescribing information for sildenafil).
Concomitant use of St. Johns wort (Hypericum perforatum) or St. Johns wort-containing products and RESCRIPTOR is not recommended. Coadministration of St. Johns wort with NNRTIs, including RESCRIPTOR, is expected to substantially decrease NNRTI concentrations and may result in suboptimal levels of RESCRIPTOR and lead to loss of virologic response and possible resistance to RESCRIPTOR or to the class of NNRTIs.

# Precautions

## General
Delavirdine is metabolized primarily by the liver. Therefore, caution should be exercised when administering RESCRIPTOR Tablets to patients with impaired hepatic function.
- Immune reconstitution inflammatory syndrome
- Autoimmune disorders (such as Graves disease, polymyositis, and Guillain-Barre syndrome) have also been reported to occur in the setting of immune reconstitution; however, the time to onset is more variable, and can occur many months after initiation of treatment.

## Resistance/Cross-Resistance
NNRTIs, when used alone or in combination, may confer cross-resistance to other NNRTIs.

## Fat Redistribution
Redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and "cushingoid appearance" have been observed in patients receiving antiretroviral therapy. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established.

## Skin Rash
Severe rash, including rare cases of erythema multiforme and Stevens-Johnson syndrome, has been reported in patients receiving RESCRIPTOR. Erythema multiforme and Stevens-Johnson syndrome were rarely seen in clinical trials and resolved after withdrawal of RESCRIPTOR. Any patient experiencing severe rash or rash accompanied by symptoms such as fever, blistering, oral lesions, conjunctivitis, swelling, and muscle or joint aches should discontinue RESCRIPTOR and consult a physician. Two cases of Stevens-Johnson syndrome have been reported through postmarketing surveillance out of a total of 339 surveillance reports.
In Studies 21 Part II and 13C (see  DESCRIPTION OF CLINICAL STUDIES), rash (including maculopapular rash) was reported in more patients who were treated with RESCRIPTOR 400 mg 3 times daily (35% and 32%, respectively) than in those who were not treated with RESCRIPTOR (21% and 16%, respectively). The highest intensity of rash reported in these studies was severe (Grade 3), which was observed in approximately 4% of patients treated with RESCRIPTOR in each study and in none of the patients who were not treated with RESCRIPTOR. Also in Studies 21 Part II and 13C, discontinuations due to rash were reported in more patients who received RESCRIPTOR 400 mg 3 times daily (3% and 4%, respectively) than in those who did not receive RESCRIPTOR (0% and 1%, respectively).
In most cases, the duration of the rash was less than 2 weeks and did not require dose reduction or discontinuation of RESCRIPTOR. Most patients were able to resume therapy after rechallenge with RESCRIPTOR following a treatment interruption due to rash. The distribution of the rash was mainly on the upper body and proximal arms, with decreasing intensity of the lesions on the neck and face, and progressively less on the rest of the trunk and limbs.
Occurrence of a delavirdine-associated rash after 1 month is uncommon. Symptomatic relief has been obtained using diphenhydramine hydrochloride, hydroxyzine hydrochloride, and/or topical corticosteroids.