Side Effects of Rescriptor (delavirdine)

Rescriptor (delavirdine) is a reverse transcriptase inhibitor used to treat infections with the human immunodeficiency virus (HIV). 

During infection with HIV, the HIV virus multiplies within the body's cells. The newly-formed viruses then are released from the cells and spread throughout the body where they infect other cells. 

In this manner, the infection spreads to new, uninfected cells that the body is continually producing, and HIV infection is perpetuated. When producing new virus, the HIV virus must manufacture new DNA for each virus. 

Reverse transcriptase is the enzyme that the virus uses to form this new DNA. Rescriptor directly inhibits the activity of reverse transcriptase and blocks the production of DNA and new virus. Rescriptor does not kill existing HIV virus, and it is not a cure for HIV. 

Common side effects of Rescriptor include

• rash,
• headaches,
• diarrhea,
• nausea,
• vomiting and
• weakness.

Other important side effects of Rescriptor include

• agitation,
• difficulty sleeping,
• abdominal cramps, and
• muscle pain.

Drug interactions of Rescriptor include atorvastatin, fluvastatin, indinavir, lopinavir and ritonavir, nelfinavir, ritonavir, saquinavir, and sildenafil because Rescriptor can raise blood levels of these drugs, which could increase side effects.

• Many other drugs can interact with Rescriptor, including ADHD medications such as Adderall, cholesterol-lowering medications, antibiotic or antifungal medicines, heart or blood pressure medicines, medicines to prevent organ transplant rejection, and medicines to reduce stomach acid. 

No adequate and well-controlled studies of Rescriptor in pregnant women have been conducted. Rescriptor should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. 

It is unknown if Rescriptor is secreted in breast milk. HIV-infected mothers should not breastfeed their infants because of the risk of transmitting HIV to an infant that is not infected.

The most common side effects of delavirdine are:

• rash,
• headaches,
• diarrhea,
• nausea,
• vomiting and
• weakness.

Other important side effects include

• agitation,
• difficulty sleeping,
• abdominal cramps, and
• muscle pain.

The safety of Rescriptor Tablets alone and in combination with other therapies has been studied in approximately 6,000 patients receiving Rescriptor. The majority of adverse events were of mild or moderate (i.e., ACTG Grade 1 or 2) intensity.

The most frequently reported drug-related adverse event (i.e., events considered by the investigator to be related to the blinded study medication or events with an unknown or missing causal relationship to the blinded medication) among patients receiving Rescriptor was skin rash (see Table 8).

Table 8: Percent of Patients With Treatment-Emergent Rash in Pivotal Trials (Studies 21 Part II and 13C)^a

Adverse events of moderate to severe intensity reported by at least 5% of evaluable patients in any treatment group in the pivotal trials, which includes patients receiving Rescriptor in combination with zidovudine and/or lamivudine in Study 21 Part II for up to 98 weeks and in combination with zidovudine and either lamivudine, didanosine, or zalcitabine in Study 13C for up to 72 weeks are summarized in Table 9.

Table 9: Treatment-Emergent Events Regardless of Causality, of Moderate-to-Severe or Life-Threatening Intensity Reported by at Least 5% of Evaluable^a Patients in Any Treatment Group

• Other Adverse Events in Phase II/III Studies: Other adverse events that occurred in patients receiving Rescriptor (in combination treatment) in all Phase II and III studies, considered possibly related to treatment, and of at least ACTG Grade 2 in intensity are listed below by body system.
• Body as a Whole: Abdominal cramps, abdominal distention, abdominal pain (localized), abscess, allergic reaction, chills, edema (generalized or localized), epidermal cyst, fever, infection, infection viral, lip edema, malaise, Mycobacterium tuberculosis infection, neck rigidity, sebaceous cyst, and redistribution/accumulation of body fat.
• Cardiovascular System: Abnormal cardiac rate and rhythm, cardiac insufficiency, cardiomyopathy, hypertension, migraine, pallor, peripheral vascular disorder, and postural hypotension.
• Digestive System: Anorexia, bloody stool, colitis, constipation, decreased appetite, diarrhea (Clostridium difficile), diverticulitis, dry mouth, dyspepsia, dysphagia, enteritis at all levels, eructation, fecal incontinence, flatulence, gagging, gastroenteritis, gastroesophageal reflux, gastrointestinal bleeding, gastrointestinal disorder, gingivitis, gum hemorrhage, hepatomegaly, increased appetite, increased saliva, increased thirst, jaundice, mouth or tongue inflammation or ulcers, nonspecific hepatitis, oral/enteric moniliasis, pancreatitis, rectal disorder, sialadenitis, tooth abscess, and toothache.
• Hemic and Lymphatic System: Adenopathy, bruising, eosinophilia, granulocytosis, leukopenia, pancytopenia, purpura, spleen disorder, thrombocytopenia, and prolonged prothrombin time.
• Metabolic and Nutritional Disorders: Alcohol intolerance, amylase increased, bilirubinemia, hyperglycemia, hyperkalemia, hypertriglyceridemia, hyperuricemia, hypocalcemia, hyponatremia, hypophosphatemia, increased AST (SGOT), increased gamma glutamyl transpeptidase, increased lipase, increased serum alkaline phosphatase, increased serum creatinine, and weight increase or decrease.
• Musculoskeletal System: Arthralgia or arthritis of single and multiple joints, bone disorder, bone pain, myalgia, tendon disorder, tenosynovitis, tetany, and vertigo.
• Nervous System: Abnormal coordination, agitation, amnesia, change in dreams, cognitive impairment, confusion, decreased libido, disorientation, dizziness, emotional lability, euphoria, hallucination, hyperesthesia, hyperreflexia, hypertonia, hypesthesia, impaired concentration, manic symptoms, muscle cramp, nervousness, neuropathy, nystagmus, paralysis, paranoid symptoms, restlessness, sleep cycle disorder, somnolence, tingling, tremor, vertigo, and weakness.
• Respiratory System: Chest congestion, dyspnea, epistaxis, hiccups, laryngismus, pneumonia, and rhinitis.
• Skin and Appendages: Angioedema, dermal leukocytoclastic vasculitis, dermatitis, desquamation, diaphoresis, discolored skin, dry skin, erythema, erythema multiforme, folliculitis, fungal dermatitis, hair loss, herpes zoster or simplex, nail disorder, petechiae, non-application site pruritus, seborrhea, skin hypertrophy, skin disorder, skin nodule, Stevens-Johnson syndrome, urticaria, vesiculobullous rash, and wart.
• Special Senses: Blepharitis, blurred vision, conjunctivitis, diplopia, dry eyes, ear pain, parosmia, otitis media, photophobia, taste perversion, and tinnitus.
• Urogenital System: Amenorrhea, breast enlargement, calculi of the kidney, chromaturia, epididymitis, hematuria, hemospermia, impaired urination, impotence, kidney pain, metrorrhagia, nocturia, polyuria, proteinuria, testicular pain, urinary tract infection, and vaginal moniliasis.

Postmarketing Experience

Adverse event terms reported from postmarketing surveillance that were not reported in the Phase II and III trials are presented below.

• Digestive System: Hepatic failure.
• Hemic and Lymphatic System: Hemolytic anemia.
• Musculoskeletal System: Rhabdomyolysis.
• Urogenital System: Acute kidney failure.

Laboratory Abnormalities

Marked laboratory abnormalities observed in at least 2% of patients during Studies 21 Part II and 13C are summarized in Table 10. Marked laboratory abnormalities are defined as any Grade 3 or 4 abnormality found in patients at any time during study.

Table 10:Marked Laboratory Abnormalities Reported by ≥ 2% of Patients

• Delavirdine is an inhibitor of CYP3A isoform and other CYP isoforms to a lesser extent including CYP2C9, CYP2D6, and CYP2C19.
• Coadministration of Rescriptor and drugs primarily metabolized by CYP3A (e.g., HMG-CoA reductase inhibitors and sildenafil) may result in increased plasma concentrations of the coadministered drug that could increase or prolong both its therapeutic or adverse effects.
• Delavirdine is metabolized primarily by CYP3A, but in vitro data suggest that delavirdine may also be metabolized by CYP2D6.
• Coadministration of Rescriptor and drugs that induce CYP3A, such as rifampin, may decrease delavirdine plasma concentrations and reduce its therapeutic effect.
• Coadministration of Rescriptor and drugs that inhibit CYP3A may increase delavirdine plasma concentrations. (See 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.)

Table 6: Drugs That Should Not Be Coadministered With Rescriptor

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