Pneumonia Flashcards
(35 cards)
Define the terms clearance (CL), half-life (t), volume of distribution (V)
Clearance - volume of plasma cleared of a drug in unit time
Half-life - the amount of time it takes for a drug concentration to decrease by half
Volume of distribution - the apparent volume in which a drug is dissolved in the body
Calculate V from a plot of log (plasma level) versus time.
Vd = amount in the body/concentration = dose/concentation at t=0
State that CL Clrenal Clhepatic, and be able to predict the consequence of change in either component on the plasma drug concentrations.
Clearance = clRenal + clHeapatic
State that at steady state Administration Rate Elimination Rate.
The steady state (Css, which is concentration steady state) is where the administration rate is equal to the elimination rate. Administration of a drug at a constant rate is a zero order process. Elimination is a first order process.
State the relationship between rate of drug infusion and steady state blood level.
Infusion Rate = Clearance x Concentration Steady State
Identify the pharmacokinetic parameters that are used to describe the rate and extent of drug absorption from an oral dose.
- rapid-release formulation, the rise to the peak is extremely quick.
- sustained release formulation, there is a prolonged absorption superimposed on elimination and the half-life is not a true elimination half-life and is known as ‘context-sensitive half-life’ or ‘functional half-life’.
Define the term bioavailability (F), state the use of AUC values to calculate F.
F - the fraction of a drug absorbed
F = (AUCoral)/(AUCiv)
Identify the factors that determine the time to steady state, the steady state concentration, and the fluctuations around this concentration on repeat dosing of a drug.
dose interval, bioavailability, clearance
Identify three factors of importance when designing a dosage regimen.
In a short half-life drug (usually around one hour) with a wide therapeutic window, it is given three to four times per day. A drug with a short half-life with a narrow therapeutic window, intravenous infusion is used.
Define a loading dose and a maintenance dose and define what pharmacokinetic parameters are required to set these values for an individual drug.
Loading Dose = (Target Steady Sate x Volume Distribution)/Bioavailability.
Maintenance Dose = (Target Steady State x Clearance x Tau)/Bioavailability
The maintenance dose for drugs with a long half life is the amount eliminated per day as a daily dosing regimen is optimal for patient compliance.
Describe the principles of antimicrobial chemotherapy
antimicrobial chemotherpay is the use of drugs to selectively kill bacteria (and viruses / fungi) without affecting the host. The targets are the bacterial cell wall, bacterial ribosomes, bacterial folate metabolism, bacterial DNA gyrases. Antibiotics are produced by an organism to attack other organisms. Antibacterials are also used and are usually man-made.
Be able to describe the mechanisms of action of: 1)Beta-lactam antibiotics 2)Macrolides 3)Tetracyclines 4)Folate inhibitors 5)Quinolones 6) Aminoglycosides
Beta-lactams: target bacterial cell wall synthesis by binding irreversibly to a transpeptidase which cross-links peptidoglycans in the bacterial cell wall.
Macrolides: Macrolides prevent the translocation of the 50S subunit of the bacterial ribosome along the mRNA. This prevents protein synthesis.
Tetracyclines: inhibit protein synthesis by binding to the 30S subunit of the bacterial ribosome and prevents tRNA from binding at the acceptor (A) site.
Folate Inhibitors: inhibits the bacterial dihydrofolate reductase, which converts folate to tetrahydrofolate. It is less potent against the human form of the enzymes needed to form DNA.
Quinolones: These are inhibitors of bacterial DNA gyrase and topoisomerase IV. In gram negative bacteria, DNA gyrase is inhibited and quinolone inhibits the supercoiling of the bacterial DNA, which is essential for DNA repair and replication. In gram positive bacteria, topoisomerase IV is the target and quinolones interfere with the separation of DNA strands on replication. They are bactericidal.
Aminoglycosides: These bind irreversibly to the 30S subunit of bacterial ribosomes, leading to misreading of mRNA and interfere with protein synthesis.
Define the terms patient safety, incidents and error.
Patient safety - the freedom for patients from unnecessary or potential harm arising from health care.
Patient safety incident - any unintended or unexpected incident which could have or did lead to harm for one or more patients receiving NHS funded care.
Human error - occurs when the actions and decisions of individuals result in failures that can immediately or directly impact patient safety.
Outline the key components of a high quality healthcare organisation.
Quality care is safe, effective, timely, efficient, person-centered and equal. Safe is minimising incidents and harm, mitigating risk, continuously improving, being just and proportionate, being open and honest, supporting those in incidents and having the freedom to speak up.
Describe the main pattern of lung infection by M. tuberculosis
- grows in tissues with a high oxygen content.
- usually infectis mononuclear phagocytes.
- slow-growing and hydrophobic due a high lipid content in the cell wall. - less permeable to usual bacterial stains
Describe the investigation of suspected tuberculosis
- cultured in category 3 lab
- uses antibiotic sensitivity test
- pcr test
- dna probes
Describe the issues involved with public health, treatment, and drug resistance in tuberculosis
- people can be asymptomatically infected
- takes a long time to treat
- some strains are drug resistant
Identify and understand your role as a doctor and a communicator.
The role of the doctor is to return the patient to their health and social obligations and to provide quality of care. They may also be expected to have emotional detachment and neutrality and power and influence.
Describe how the doctor and patient role has changed over time.
In the current approach, there is a realignment of patient and doctor roles with a greater focus on patient autonomy, values and choice for patient and greater governance to oversee duty-based actions of doctors.
Apply this information to conduct a patient-centred consultation.
The doctor establishes the patient’s agenda, listens and reflects, uses open questions and seeks to promote autonomy. The patient is an active participant, asks questions, and influences the course of the consultation.
Distinguish between upper respiratory tract infections and lower respiratory tract infections
- upper respiratory tract includes the nose and nasal passages, paranasal sinuses, the pharynx, and the portion of the larynx above the vocal folds (cords).
- lower respiratory tract includes the portion of the larynx below the vocal folds, trachea, bronchi and bronchioles.
Describe the features and causative agents of infectious mononucleosis.
glandular fever infectious mononucleosis. It is a syndrome and has a constellation of symptoms and signs, not an aetiological diagnosis. There are atypical mononuclear cells in the peripheral blood.
List viral causes of LRTI.
- influenza viruses
- respiratory syncytial virus
- SARS-CoV-2.
- varicella zoster virus
- measles virus
- cytomegalovirus
- MERS and SARS coronaviruses
Describe the clinical features and pathogenesis of influenza virus infection
Influenza viruses usually have two major components of the illness. The respiratory tract symptoms, such as a cough and shortness of breath, and systemic symptoms, such as a fever, headache and myalgia.
Influenza can be pneumotropic, where it infects the cells lining the respiratory tract, down to the alveoli. The infection can also be lytic, and strips off the respiratory epithelium. It removes two innate defence mechanisms of the respiratory tract, which are the mucous secreting cells and the cilia. Interferon production circulates in the blood, but the virus doesn’t.
