CHAPTER 15 Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS)
I. Introduction and Definitions
A. The human immunodeficiency viruses (HIV-1 or HIV-2) are the viruses that cause HIV infection and the acquired immune deficiency syndrome (AIDS). HIV primarily attacks the immune system, making the patient extremely vulnerable to opportunistic infections (infections caused by pathogens that generally do not affect those with healthy immune systems). HIV primarily infects and destroys immune T-cells that have the CD4 receptor protein on their cell surfaces (also called CD4-positive or CD4+ T-cells). Healthy individuals have a CD4+ cell count between 600 and 1200 cells per microliter of blood. HIV patients have less than 600 CD4+ cells per microliter of blood; the lower the CD4+ count, the weaker the immune system.
B. When a patient is determined to be HIV-positive, CD4+ cell counts and the measurement of the HIV-RNA level (a determinant of viral load) are assessed to determine when treatment should be initiated and with what medications. These tests are also monitored on a regular basis after treatment is initiated to determine clinical response. A lack of clinical response to treatment may indicate viral resistance or patient noncompliance, and a regimen change may be needed.
C. HIV infection progresses to AIDS if the CD4+ cell counts drop to less than 200 cells per microliter. This may happen if the infected individual receives inadequate treatment or develops a major infection. Individuals with a CD4+ cell count less than 200 have the greatest risk of developing opportunistic infections, such as Pneumocystis pneumonia (PCP), Mycobacterium avium complex (MAC) infections, or Kaposi sarcoma.
D. According to the United States Centers for Disease Control and Prevention (CDC), approximately 56,300 patients were newly infected with HIV in 2006, which is a 40% increase from the 40,000 annual estimate used for past years. The increased number may be due to more accurate lab testing and new statistical methods, not a worsening of the epidemic. The number of AIDS-related deaths continues to decline, with an 8% decrease from 2000 through 2004. Advanced treatments can attribute to increased survival, thus resulting in an increased number of people in the United States who are living with HIV infection and AIDS.
II. Signs and Symptoms
A. Many patients are asymptomatic when they first become infected with HIV. One to 2 months after infection, some HIV patients develop flu-like or mononucleosis-like symptoms that last about 1 to 3 weeks. For the next several months or years, patients usually do not experience any symptoms of the disease. Once this asymptomatic period ends, symptoms may include enlarged lymph nodes (persistent lymphadenopathy), fatigue, weight loss, frequent fevers and sweats, persistent or frequent yeast infections of the mouth or vagina, persistent skin rashes, flaky skin, pelvic inflammatory disease (PID) in women, and short-term memory loss. As the immune system continues to weaken, patients may eventually progress to AIDS. During this stage, patients have the greatest risk of developing life-threatening opportunistic infections. HIV-related cachexia, HIV-associated dementia, and certain cancers may also occur in late-stage disease.
III. Treatment
A. Antiretroviral agents should be used in combination with at least three agents, a strategy known as highly active antiretroviral therapy (HAART). In the United States, updated treatment guidelines, drug information, and other resources formulated for consumers and healthcare professionals can be found at the following website: (www.aidsinfo.nih.gov)
B. Initial combination regimen (antiretroviral naïve patients): use either a nonnucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI) or integrase strand transfer inhibitor (INSTI) in combination with at least two nucleoside/nucleotide reverse transcriptase inhibitors (NRTI):
1. Individual antiretroviral agents used in treatment of HIV-positive patients
(a) NRTI
Table 15-1 Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTI) Combination Products
| Brand Name | Active Ingredients | Normal Adult Dosage |
|---|---|---|
| Atripla | 1 PO qd | |
| Combivir | 1 PO bid | |
| Epzicom | 1 PO qd | |
| Trizivir | 1 PO bid | |
| Truvada | 1 PO qd |
(iii) Adverse effects (primary drug examples noted in parenthesis where relevant):
a. All have boxed warning: lactic acidosis with hepatic steatosis. Gastrointestinal disturbances (diarrhea, nausea/vomiting), and headache are common side effects of all.
