P
An HIV protein. p24 forms HIV's viral core.
See Related Term(s): Core
Also known as: Prescribing Information, Prescription Drug Labeling, Product Label
Drug prescribing information prepared by the drug manufacturer and approved by the Food and Drug Administration (FDA). The package insert includes details and directions that health care providers need to prescribe a drug properly, including approved uses for the drug, contraindications, potential adverse reactions, available formulations and dosage, and how to administer the drug. The package insert is included with drug packaging and is used to develop any promotional or labeling materials.
See Related Term(s): Food and Drug Administration
Care to alleviate the physical and psychological symptoms of disease or the undesirable effects of treatment. The goal of palliative care is not to cure disease but to make the person more comfortable and improve the person's quality of life. Palliative care may be given at any stage of a disease.
A gland located behind the stomach. The pancreas secretes enzymes that aid in digestion and produces several hormones, including insulin and glucagon, which regulate blood sugar levels.
See Related Term(s): Insulin
Inflammation of the pancreas. Symptoms of acute and chronic pancreatitis are similar and can include pain, nausea and vomiting, and a swollen abdomen. Gallstones are the most common cause of acute pancreatitis. Chronic, heavy alcohol use is a common cause of both acute and chronic pancreatitis. Pancreatitis may also be caused by use of certain antiretroviral (ARV) drugs or an opportunistic infection.
See Related Term(s): Pancreas
Lower-than-normal levels of blood cells (red blood cells and white blood cells) and platelets.
An epidemic of disease, or other health condition, that occurs over a widespread area (multiple countries or continents) and usually affects a sizeable part of the population.
See Related Term(s): Epidemic
Also known as: Pap Test
A procedure in which cells and secretions are collected from inside and around the cervix for examination under a microscope. Pap smear also refers to the laboratory test used to detect any infected, potentially pre-cancerous, or cancerous cells in the cervical cells obtained from a Pap smear.
See Related Term(s): Cervix
A benign (not cancerous) growth, such as a wart, on the skin or mucous membrane.
Any organism that lives on or in another living organism (the host) and gets its food from or at the expense of the host. The host does not benefit from the parasite. Many parasites cause disease in humans. People with weakened immune systems, including people with HIV, are at a higher risk for parasitic infections than people with healthy immune systems.
When a substance, such as a drug or solution, is introduced into the body through a route other than the gastrointestinal (GI) tract. (The GI tract extends from the mouth to the anus.) For example, a parenteral drug may be given through the veins (intravenous), into the muscles (intramuscular), or through the skin (subcutaneous). Parenteral nutrition refers to feeding a person intravenously.
Abnormal touch sensations, such as burning, prickling, or tingling, that occur spontaneously. Paresthesia usually occurs in the hands, arms, legs, or feet, but it can occur in other parts of the body, too. Chronic paresthesia may be due to underlying neurological disease, traumatic nerve damage, or peripheral neuropathy. Paresthesia may also be caused by use of certain antiretroviral (ARV) drugs.
See Related Term(s): Peripheral Neuropathy
Immunity that develops after a person receives immune system components, most commonly antibodies, donated from another person. Passive immunity can occur naturally, such as when an infant receives a mother’s antibodies through the placenta or breast milk, or artificially, such as when a person receives antibodies in the form of an injection (gamma globulin injection). Passive immunity provides immediate protection against an antigen, but does not provide long-lasting protection.
See Related Term(s): Acquired Immunity, Active Immunity, Antibody
A type of immunotherapy in which donated or laboratory-made immune system components or cellular proteins are given to a person to help the person fight an infection or disease. Passive immunotherapy using antibodies is often used in cancer treatment.
See Related Term(s): Immunotherapy
Any disease-causing microorganism, such as a bacterium or virus.
The origin and development of a disease. Pathogenesis includes the specific processes that occur during the development of a disease.
Peak Concentration
Also Known As: Cmax
Pediatric AIDS Clinical Trials Group (PACTG) 
(En español)
A large clinical trials network that evaluates treatments for HIV-infected children and adolescents and that develops new therapeutic approaches for preventing mother-to-child transmission of HIV. Originally an independent network, Pediatric AIDS Clinical Trials Group (PACTG) investigators are now merged with the International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) Group.
See Related Term(s): International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) Group
Pediatric AIDS Clinical Trials Group 076 (PACTG 076) (En español)
A federally funded study that determined that the risk of mother-to-child transmission (MTCT) of HIV could be reduced by nearly 70% if the antiretroviral (ARV) drug zidovudine was given to a woman during pregnancy and labor and delivery and to the newborn. The Pediatric AIDS Clinical Trials Group 076 (PACTG 076) study contributed greatly to preventing MTCT of HIV.
Pelvic Inflammatory Disease (PID) (En español)
Infection and inflammation of the female upper genital tract, including the uterus and fallopian tubes. Pelvic inflammatory disease (PID) is usually due to bacterial infection, including some sexually transmitted infections, such as chlamydia and gonorrhea. Symptoms, if any, include pain in the lower abdomen, fever, smelly vaginal discharge, irregular bleeding, or pain during intercourse. PID can lead to serious complications, including infertility, ectopic pregnancy (a pregnancy in the fallopian tube or elsewhere outside of the womb), and chronic pelvic pain.
Penicillium Marneffei Infection (En español)
Also known as: Penicilliosis
A disease caused by the fungus
Penicillium marneffei, which is endemic in Southeast Asia (especially Northern Thailand). Symptoms include fever, anemia, weight loss, and skin lesions.
Penicillium marneffei infection occurs mostly in people with weakened immune systems, such as people with HIV. Without timely antifungal treatment, the disease can be fatal.
See Related Term(s): Opportunistic Infection
Amino acids that are chemically linked to one another. Proteins are made of peptides.
See Related Term(s): Amino Acids, Protein
Pertaining to the area around the anus.
The time period that extends from about mid-way before birth to after birth. This time period begins the 20th week of gestation and ends 4 weeks after birth. Perinatal transmission of HIV refers to the passage of HIV from an infected mother to her child during pregnancy, labor and delivery, or breastfeeding (through breast milk).
See Related Term(s): Mother-to-Child Transmission
Peripheral Blood Mononuclear Cell (PBMC) (En español)
A type of white blood cell that contains one nucleus, such as a lymphocyte or macrophage.
See Related Term(s): White Blood Cell
Peripheral Nervous System (PNS) (En español)
The part of the nervous system that is made up of the nerves outside of the brain and spinal cord. The peripheral nervous system (PNS) transmits information from the brain and spinal cord to the rest of the body; it also transmits sensory information back to the brain and spinal cord. HIV infection or use of certain antiretroviral (ARV) drugs can cause damage to the PNS.
See Related Term(s): Peripheral Neuropathy
Damage to the peripheral nervous system, which includes the nerves outside of the brain and spinal cord. Symptoms include pain, numbness, tingling, swelling, and muscle weakness. Peripheral neuropathy may be due to injury, infection, disease (such as diabetes), autoimmune diseases (such as chronic inflammatory demyelinating polyneuropathy), or certain antiretroviral (ARV) drugs.
See Related Term(s): Neuropathy, Peripheral Nervous System
Persistent Generalized Lymphadenopathy (PGL) (En español)
Enlarged lymph nodes (lymphadenopathy) in at least two areas of the body for at least 3 months. In people with HIV, persistent generalized lymphadenopathy (PGL) is associated with early stages of HIV infection and with certain opportunistic infections.
See Related Term(s): Lymph Nodes
The processes by which a drug is absorbed, distributed, metabolized, and eliminated by the body.
See Related Term(s): Pharmacology
The study of drugs. Pharmacology includes the study of a drug’s composition, pharmacokinetics, therapeutic use, and toxicity.
See Related Term(s): Pharmacokinetics
The first step in testing an experimental drug in humans. Phase I trials evaluate the drug's safety and toxicity at different dose levels and determine drug pharmacokinetics. Because little is known about the possible risks and benefits of the drug being tested, Phase I trials usually include only a small number of participants (20 to 80). Testing of other biomedical interventions, such as diagnostic tests or medical devices, also begins with Phase I trials.
See Related Term(s): Clinical Trial, Pharmacokinetics, Phase II Trial, Phase III Trial, Phase IV Trial
The second step in testing an experimental drug (or other treatment) in humans. Typically, Phase II trials are done only if Phase I trials have shown that the drug is safe, but sometimes Phase I and Phase II trials are combined. Phase II trials are designed to evaluate the drug's effectiveness in people with the disease or condition being studied and to determine the common short-term adverse effects and risks associated with the drug. Phase II trials involve more participants (often several hundred) and typically last longer than Phase I trials.
See Related Term(s): Clinical Trial, Phase I Trial, Phase III Trial, Phase IV Trial
The third step in testing an experimental drug (or other treatment) in humans. Phase III trials are conducted to confirm and expand on safety and effectiveness results from Phase I and II trials, to compare the drug to standard therapies for the disease or condition being studied, and to evaluate the overall risks and benefits of the drug. This trial phase recruits a large group of people with the disease or condition, usually ranging from 1,000 to 3,000 participants. Results from Phase III trials provide information that the Food and Drug Administration (FDA) needs to consider the drug for approval.
See Related Term(s): Clinical Trial, Food and Drug Administration, Phase I Trial, Phase II Trial, Phase IV Trial
Testing in humans that occurs after a drug (or other treatment) has already been approved by the Food and Drug Administration (FDA) and is being marketed for sale. Phase IV trials are conducted to determine long-term safety and effectiveness and to identify adverse effects that may not have been apparent in prior trials. Thousands of participants are usually recruited to volunteer for this phase of clinical testing.
See Related Term(s): Clinical Trial, Food and Drug Administration, Phase I Trial, Phase II Trial, Phase III Trial
Phenotypic Antiretroviral Resistance Test (En español)
Also known as: Phenotypic Assay
A type of resistance test that measures the extent to which a person's strain of HIV will multiply in different concentrations of antiretroviral (ARV) drugs. Resistance testing is used to guide selection of an HIV regimen when initiating or changing antiretroviral therapy (ART).
See Related Term(s): Genotypic Antiretroviral Resistance Test, Resistance Testing
Abnormal sensitivity to light. Symptoms may include reddening and blistering of the skin. Use of some antiretroviral (ARV) drugs may cause photosensitivity reactions.
Combination antiretroviral therapy (ART) that does not include antiretroviral (ARV) drugs from the protease inhibitor (PI) drug class. Excluding PIs from an HIV treatment regimen saves drugs in the PI class for future use.
See Related Term(s): Protease Inhibitor
The number of tablets, capsules, or other dosage forms that a person takes on a regular basis. A high pill burden can make it difficult to adhere to an HIV treatment regimen.
See Related Term(s): Adherence
Also known as: Sham, Sugar Pill
An inactive drug (or other intervention) that is identical in appearance to a therapeutically active drug. In some clinical trials, researchers compare the effects of a placebo with those of an active drug under investigation to determine if the active investigational drug is effective.
See Related Term(s): Placebo Effect, Placebo-Controlled Trial
An effect (usually, but not necessarily, beneficial) that arises from an expectation that the given drug (or other intervention) will have an effect. In a clinical trial, placebo effect can refer to an effect experienced by either a participant or a researcher.
See Related Term(s): Placebo
Placebo-Controlled Trial (En español)
A type of clinical trial. In placebo-controlled trials, one group of participants (the control arm) receives an inactive drug (or other intervention), called a placebo, while another group of participants (the experimental arm) receives the active drug being tested. The two groups are compared to see if the drug is more effective than the placebo.
See Related Term(s): Placebo
The sac-shaped organ that develops in the uterus of a pregnant woman. The placenta provides the fetus with oxygen and nutrients and takes away wastes, such as carbon dioxide, via the umbilical cord.
The clear, yellowish liquid part of blood. Plasma carries red blood cells, white blood cells, and platelets throughout the body.
An irregularly shaped cell-like particle found in the blood. Platelets cause blood clots to form, which helps prevent bleeding.
Pneumocystis Jiroveci Pneumonia (En español)
Also known as: Pneumocystis Pneumonia, Pneumocystis Carinii Pneumonia, Pneumocystosis
Formerly known as
Pneumocystis carinii pneumonia (PCP). A lung infection caused by the fungus
Pneumocystis jiroveci. Symptoms include a cough (often mild and dry), fever, and shortness of breath. The fungus is common in the environment and does not cause illness in healthy people.
Pneumocystis jiroveci pneumonia occurs only in people with weakened immune systems. In people with HIV,
Pneumocystis jiroveci pneumonia is an AIDS-defining condition.
See Related Term(s): AIDS-Defining Condition, Opportunistic Infection
Also known as: Bronchopneumonia
Inflammation of the lungs, which is usually caused by a bacterial, viral, or fungal infection. People older than 65 years of age or younger than 2 years of age and people with weakened immune systems are more at risk for pneumonia. Symptoms include cough, shortness of breath, fevers, chills, chest pain, and weakness. In people with HIV, recurrent pneumonia (pneumonia that returns again and again) is considered an AIDS-defining condition.
See Related Term(s): AIDS-Defining Condition
Polymerase Chain Reaction (PCR) (En español)
A laboratory technique used to produce large amounts of specific DNA fragments. PCR is used for genetic testing and to diagnose disease.
Neuropathy that damages multiple nerves.
See Related Term(s): Neuropathy
Also known as: Multivalent Vaccine
A vaccine that immunizes against more than one antigen. An example of a polyvalent vaccine is the MMR vaccine, which immunizes against three viruses—the viruses that cause measles, mumps, and rubella.
See Related Term(s): Antigen, Vaccine
The time period after birth. Postnatal refers to the newborn.
The time period after childbirth. Postpartum refers to the mother.
Pre-Exposure Prophylaxis (PrEP) (En español)
Administration of antiretroviral (ARV) drugs before potential HIV exposure in order to reduce the risk of HIV infection. Clinical trials are underway to determine if pre-exposure prophylaxis (PrEP) is a safe and effective way to reduce HIV transmission in people at high risk for HIV infection.
Preliminary testing of an investigational drug (or other intervention) in laboratory animals. Preclinical studies are used to determine a drug’s effects and safety in laboratory animals before Phase I clinical trials in humans can begin.
See Related Term(s): Clinical Trial, Phase I Trial
Preconception Counseling and Care (En español)
Ongoing education and care to improve the health of a woman before pregnancy. Preconception counseling and care involves identifying and managing conditions and behaviors that could put the woman or her baby at risk. For women with HIV, this includes counseling on the risks and benefits of antiretroviral (ARV) drugs to prevent mother-to-child transmission (MTCT) of HIV.
See Related Term(s): Mother-to-Child Transmission
Also known as: Antenatal
The time period before birth. Prenatal can refer to both the woman and the fetus.
President's Emergency Plan for AIDS Relief (PEPFAR) (En español)
The U.S. government global initiative to combat the HIV/AIDS epidemic. The President's Emergency Plan for AIDS Relief (PEPFAR) works with governmental and non-governmental partners worldwide to support integrated HIV prevention, treatment, and care programs. PEPFAR places emphasis on improving health outcomes, increasing program sustainability and integration, and strengthening health systems.
Based on a reasonable assumption. In non-breastfed infants born to HIV-infected mothers, presumptive exclusion of HIV infection is based on two or more negative HIV tests, one at age 14 days or older and the other at age 1 month or older. Additional testing is necessary to definitively exclude HIV infection.
See Related Term(s): Definitive
The number or proportion of people with a particular disease or condition in a given population and at a specific time.
See Related Term(s): Incidence
Prevention of Mother-to-Child Transmission (PMTCT) (En español)
Strategies used to prevent the spread (transmission) of HIV from an HIV-infected mother to her child during pregnancy, during labor and delivery, or by breastfeeding (through breast milk). Strategies include antiretroviral (ARV) prophylaxis for the mother during pregnancy and labor and delivery, scheduled cesarean delivery, ARV prophylaxis for the newborn infant, and avoidance of breastfeeding.
Primary Immune Complex Reaction (En español)
A type of hypersensitivity reaction that results from interactions between a drug and the immune system. During a primary immune complex reaction, antigens and antibodies clump together to form immune complexes. These immune complexes then damage body tissue. This rare but serious drug reaction can occur with use of certain antiretroviral (ARV) drugs.
See Related Term(s): Hypersensitivity
Also known as: Primary Prevention
Drugs or other forms of treatment used to prevent the development of a disease in a person who is at risk for but with no prior history of the disease. For example, primary prophylaxis is used to prevent people with advanced HIV infection from developing opportunistic infections, such as toxoplasmosis.
See Related Term(s): Maintenance Therapy
Inflammation of the anus and rectum.
An early symptom that indicates the onset of a disease.
Programmed Cell Death
Also Known As: Apoptosis
Progressive Multifocal Leukoencephalopathy (PML) (En español)
A rare disorder of the central nervous system caused by the John Cunningham virus (JCV). Most people are infected with JCV by 10 years of age; however, only people with weakened immune systems develop progressive multifocal leukoencephalopathy (PML). PML is primarily characterized by damage to myelin in the brain. Symptoms of PML vary and can include headache, loss of coordination, loss of speech, vision problems, and progressive weakness in the arms and legs. In people with HIV, PML is an AIDS-defining condition.
See Related Term(s): AIDS-Defining Condition, Central Nervous System, Myelin, Opportunistic Infection
Prophylactic
Also Known As: Condom
A type of enzyme that breaks down proteins into smaller proteins or smaller protein units, such as peptides or amino acids. HIV protease cuts up large precursor proteins into smaller proteins. These smaller proteins combine with HIV’s genetic material to form a new HIV virus. Protease inhibitors (PIs) prevent HIV from replicating by blocking protease.
See Related Term(s): Life Cycle, Maturation, Protease Inhibitor
Antiretroviral (ARV) HIV drug class. Protease inhibitors (PIs) block protease (an HIV enzyme). This prevents new HIV from forming.
See Related Term(s): Drug Class, Protease
A large molecule made up of a series of peptides—one or more long chains of amino acids. The specific sequence of the amino acids determines the protein’s structure and function. Proteins are essential to all living organisms.
See Related Term(s): Amino Acids
Excess protein in the urine. Proteinuria is a sign of chronic kidney disease, which can result from diabetes, high blood pressure, and diseases that cause inflammation in the kidneys. Proteinuria can also occur if antiretroviral (ARV) drugs damage the kidneys.
The detailed plan for conducting a clinical trial. The protocol is carefully designed to safeguard the health of participants and to answer specific research questions. The protocol describes what the trial will do, how it will be carried out, and why each part of the trial is necessary. Each person participating in a clinical trial must agree to the rules set out by the protocol.
See Related Term(s): Clinical Trial, Eligibility Criteria
A single-celled microorganism. Some protozoans can cause disease in humans, including
Toxoplasma gondii (causes toxoplasmosis), the group
Plasmodium (causes malaria), and the group
Cryptosporidium (causes cryptosporidiosis). People with weakened immune systems, including people with HIV, are at a higher risk for protozoan infections than people with healthy immune systems.
Also known as: Proviral DNA
HIV DNA that has integrated into the DNA of the host cell. When HIV enters a host cell, HIV RNA is first changed to HIV DNA (provirus). The provirus then gets inserted into the DNA of the host cell. When the host cell replicates, the HIV provirus is passed from one cell generation to the next, ensuring ongoing replication of HIV.
See Related Term(s): Integration
An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief. Common causes of pruritus include allergic reactions, insect bites, and reactions to medications.
A service of the U.S. National Library of Medicine that provides free access to an extensive database of citations and abstracts for biomedical literature, life science journals, and online books. Citations may include links to full-text content and to related resources.
See Related Term(s): National Library of Medicine