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Medical Pharmacology Chapter 36: Antiviral Drugs
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Antiviral Drugs
Anti-viral drugs with activity against HIV (Human Immunodeficiency Virus)
HIV-1 Pathophysiology/Pathogenesis: HIV Disease Presentations
Secondary bacterial, viral, and protozoal infections of the intestines can cause diarrhea, abdominal pain and elevated temperature in HIV-infected individuals.2
Bacteria possibly responsible for secondary G.I. tract infections include enteric pathogens such as Salmonella, Shigella and Campylobacter.
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Patients with untreated HIV exhibit about a 20-fold increased risk of Salmonella typhimurium (S. typhimurium).2
Patient clinical presentations may include nonspecific symptoms such as fever, fatigue, anorexia and malaise with a several week duration.2
Diarrhea is common and the specific diagnosis follows from blood and stool culture.2
Long-term pharmacological treatment with ciprofloxacin may be recommended.
HIV-infected individuals exhibit increase incidence of typhoid fever in those geographical regions exhibiting significant typhoid presence.
Shigella (especially Shigella flexneri) is another bacteria causing severe intestinal disease in HIV patients.
In
this group as many as half of patients develop bacteremia.
Campylobacter infections also are noted with increased frequency in HIV-infected individuals.
The most frequently isolated strain is Campylobacter jejuni (C. Jejuni).
These patients present with crampy abdominal pain, bloody diarrhea and fever; furthermore, stool analysis shows fecal leukocyte presence.
Systemic infection may also occur with bacteremia noted in up to about 10% of infected patients.
Campylobacter jejuni strains are usually sensitive erythromycin.
Infection with Mycobacterium avium complex (MAC) may also present with abdominal pain and diarrhea.2
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In
as many as 50% of diarrhea cases reported in HIV-infected
individuals pathogens are not found, even after extensive
diagnostic evaluation.5
As a result, this condition is described as AIDS enteropathy, characterized by:
Chronic diarrhea
Malnutrition and
Wasting.
Possibly such chronic diarrhea may be due to not yet identified pathogens or even by noninfectious causes including lymphoma.
Furthermore, pathogen-negative diarrhea may be due to HIV directly, infecting the enterocyte and gut lymphoid tissue.5
Wasting noted in HIV-infected patients describes a body mass index of <18.5 kg/m2.5,13
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Weight loss and wasting are still noted in patients being treated for HIV infection and weight loss of 3% or more appears associated with increased mortality.
In untreated HIV infection several factors appear important in wasting.
Factors leading to increased caloric requirements in this setting include not only increased metabolic requirements of HIV replication but also metabolic requirements associated with opportunistic infections and fever.
Reduced oral intake may occur as a result of nausea, anorexia, odynophagia, dysphasia as well as chronic diarrhea.
Additional factors include food insecurity, dementia or depression.
Nutrient malabsorption from the small intestine or pancreatic disease worsens weight loss.5
Therefore in the HIV-infected patient even an increase in caloric intake may be insufficient to compensate for nutrient loss in stool.5
A
number of approaches may be helpful in managing wasting and
weight loss.
Such strategies include HIV treatment, treatment of opportunistic disease, frequent albeit small meals combined with appetite stimulants and/or other agents.
Appetite stimulants include: megestrol acetate and dronabinol)
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Anabolic steroids (testosterone, oxandrolone, nandrolone)
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Recombinant HGH (human growth hormone)
Combinations of these approaches along with HIV replication control may result in improved nutritional status and weight.5
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