Parte di kinetics

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Questions and Answers

What is the effect of co-administering Trimethoprim with another antimicrobial?

The combination results in a bactericidal effect and can improve the final outcome.

What is the primary action of Warfarin in the body?

Warfarin prevents blood clotting by inhibiting platelet action.

How does the binding of molecules to plasma proteins affect their distribution in the body?

Only the fraction of the drug that is unbound can pass from the bloodstream to tissues.

Why are lipophilic molecules more efficient at passing membranes?

Lipophilic molecules can easily navigate through membranes due to their chemical features. Signup and view all the answers

What characterizes Cefovecin as an antibiotic?

Cefovecin is known for its high binding affinity and long half-life. Signup and view all the answers

Explain the term Fu in the context of drug metabolism.

Fu refers to the fraction of the drug that is unbound in the plasma. Signup and view all the answers

What role do xenobiotics play in relation to plasma protein binding?

Xenobiotics exploit plasma protein binding mechanisms for transport within the body. Signup and view all the answers

What is a potential misuse of Warfarin in veterinary medicine?

Warfarin can be illegally used to induce toxicity in animals. Signup and view all the answers

What is the significance of lipophilicity in drug absorption and distribution?

Lipophilic drugs can easily pass through phospholipid membranes, allowing for rapid absorption and distribution in tissues and organs. Signup and view all the answers

How does hydrophilicity affect the therapeutic use of drugs in systemic treatments?

Hydrophilic drugs may encounter absorption difficulties and may not effectively reach systemic sites of action, limiting their therapeutic use. Signup and view all the answers

What are the two scenarios presented for hydrophilic drugs in treating pneumonia?

Either the drug won't be effective for pneumonia treatment, or it can be designed to target conditions that require localized bowel treatment. Signup and view all the answers

Explain the paracellular transport mechanism in drug passage.

Paracellular transport allows drugs to pass through gaps between cells, but does not permit the drug to enter the cells directly. Signup and view all the answers

What role do active and passive transport mechanisms play in drug entry into cells?

Active transport requires energy and can move drugs against concentration gradients, while passive diffusion relies on concentration gradients and does not require energy. Signup and view all the answers

Why are unionized molecules more effective in passing through cell membranes?

Unionized and lipophilic molecules can easily diffuse through the membrane due to their compatibility with the lipid bilayer. Signup and view all the answers

What is passive diffusion and what characteristics of a drug influence it?

Passive diffusion is a concentration-dependent mechanism that does not require energy, and is influenced by the lipophilicity of the drug. Signup and view all the answers

How do xenobiotic drugs utilize the same mechanisms as nutrients in drug absorption?

Xenobiotic drugs exploit the body's transport mechanisms designed for nutrients, including various forms of active and passive transport. Signup and view all the answers

What effect does the blood-brain barrier (BBB) have on dogs with a specific genetic mutation when administered Loperamide?

It causes CNS depression and difficulty in breathing. Signup and view all the answers

How is Minamata disease caused in newborn babies, and what is a significant factor in its development?

It is caused by methyl mercury exposure, primarily from contaminated fish eaten by the mother. Signup and view all the answers

What happens to the BBB during meningitis, and what are the implications for drug treatment?

The BBB becomes less impermeable, allowing certain antibiotics to penetrate the CNS. Signup and view all the answers

Which organs experience faster drug distribution due to high perfusion rates, and why is this significant?

Organs like the SNC, kidneys, heart, and lungs experience faster distribution. Signup and view all the answers

Describe the relationship between perfusion rate and drug distribution in tissues with low perfusion rates like teeth and ligaments.

Drugs distribute slowly and in lower concentrations in tissues with low perfusion rates. Signup and view all the answers

What role does age play in the permeability of the BBB, specifically in newborns?

The BBB is more permeable in newborns, increasing the risk of neurological damage from toxins. Signup and view all the answers

How does inflammation affect the permeability of the BBB?

Inflammation can decrease BBB integrity, allowing more substances to cross. Signup and view all the answers

What is the significance of the blood-brain barrier compared to other bodily barriers like the mammary barrier?

The BBB has a more crucial role in protecting the CNS from harmful substances. Signup and view all the answers

What is the primary mechanism that allows certain drugs to be redistributed in the body?

The primary mechanism is the kinetic process that allows liposoluble drugs to pass through membranes and accumulate in adipose tissue. Signup and view all the answers

How does the redistribution of anti-parasitic drugs differ between animals and humans?

In animals, redistribution can effectively prolong the duration of drug effects, while in humans, varying body weight affects this mechanism. Signup and view all the answers

What role does perfusion play in drug distribution throughout the body?

Perfusion affects how quickly and effectively a drug can move from the bloodstream to target tissues based on blood flow to those organs. Signup and view all the answers

Explain the significance of ketamine's redistribution in patients following anesthesia.

Ketamine has a prolonged sedative effect due to its slow redistribution and metabolism, resulting in a longer recovery time. Signup and view all the answers

In the context of drug absorption, what does the term 'redistribution' specifically refer to?

Redistribution refers to the movement of a drug from highly perfused organs to less perfused tissues over time. Signup and view all the answers

Why are spot-on formulations used for antiparasitic drugs in animals?

Spot-on formulations are used because they allow lipophilic drugs to be absorbed and stored in fat, providing extended action. Signup and view all the answers

What defines a 'low-perfused organ' in relation to drug redistribution?

A low-perfused organ is characterized by having less blood flow, which results in drugs reaching these areas more slowly and at lower concentrations. Signup and view all the answers

How does the concept of kinetic effect influence the design of veterinary drug treatments?

The kinetic effect allows veterinarians to design treatments that utilize drug accumulation in tissues for prolonged therapeutic effects. Signup and view all the answers

What role does biotransformation play in the elimination of hormones in the body?

Biotransformation helps to eliminate hormones after they complete their physiological function. Signup and view all the answers

How do biotransformations relate to environmental pollutants and xenobiotics?

Biotransformations are utilized by the body to detoxify and eliminate xenobiotics, including environmental pollutants and drugs. Signup and view all the answers

Explain the significance of transforming lipophilic substances into hydrophilic compounds.

Transforming lipophilic substances into hydrophilic compounds facilitates their excretion from the body through bile or urine. Signup and view all the answers

What percentage of drugs are expected to lose efficacy after biotransformation?

It is expected that 90%-95% of drugs lose their efficacy after being biotransformed. Signup and view all the answers

What characteristics differentiate endogenous compounds from xenobiotics?

Endogenous compounds are produced naturally within the body, whereas xenobiotics are foreign substances originating from external sources. Signup and view all the answers

Why is it important for the liver's capacity for biotransformation to evolve in humans?

The evolution of the liver's biotransformation capacity allows humans to effectively eliminate a wider range of substances, including various drugs and toxins. Signup and view all the answers

Describe how biotransformation affects the bioactivity of drugs.

Biotransformation generally inactivates drugs by converting them into more hydrophilic forms, thereby reducing their bioactivity. Signup and view all the answers

In what way can drugs sometimes exploit toxic effects despite undergoing biotransformation?

Some drugs may still retain toxic effects even after being biotransformed, contrary to the expected loss of efficacy. Signup and view all the answers

What is aflatoxin B1 and how is it formed?

Aflatoxin B1 is a toxic substance produced by the fungi Aspergillus flavus that parasitizes various plants and cereals. Signup and view all the answers

Explain the biotransformation of aflatoxin B1 in the liver.

In the liver, aflatoxin B1 undergoes microsomal oxidation, but this process generates a reactive epoxide instead of a less toxic compound. Signup and view all the answers

What are the potential health consequences of DNA modification by aflatoxin B1 epoxide?

DNA modification by aflatoxin B1 epoxide can lead to hepatocellular carcinoma and other serious malignancies. Signup and view all the answers

Define 'teratogenic' and 'mutagenic' effects as they relate to aflatoxin B1.

Teratogenic effects refer to malformations in a fetus, while mutagenic effects involve mutations that can lead to cancer or death. Signup and view all the answers

Why is aflatoxin B1 monitored in food and feed?

Aflatoxin B1 is monitored due to its potential for causing carcinogenic, teratogenic, and mutagenic effects. Signup and view all the answers

What role does benzopyrene play in relation to cancer?

Benzopyrene, found in tobacco smoke, is transformed into a reactive epoxide that can lead to lung cancer. Signup and view all the answers

Describe the oxidation process of amylofloxacin to ciprofloxacin.

Amylofloxacin undergoes a phase one oxidation process, resulting in its transformation to ciprofloxacin, also known as M1. Signup and view all the answers

What does the chromatographic graph peak signify in the context of ciprofloxacin?

The first peak in the chromatographic graph represents ciprofloxacin, indicating its presence in the sample being analyzed. Signup and view all the answers

Study Notes

Pharmacokinetics

Pharmacokinetics is the study of how drugs move through the body.
It encompasses administration, distribution, metabolism, and elimination (ADME).
Pharmacodynamics is the study of how drugs affect the body.
It focuses on the mechanisms of drug action, such as binding to receptors or altering blood osmolarity.

Drug Administration Routes

Drugs can be administered orally, parentally (IV, IM, SC, etc), or topically.
Formulation is tailored to the route; a pill is not suitable for injection.

Absorption

Absorption is the movement of a drug from the site of administration to the bloodstream.
Factors like drug solubility, ionization (pH), and other components of the formulation affect absorption.
The absorption rate impacts the time it takes for a drug to have an effect.

Distribution

Distribution is the movement of a drug from the bloodstream to various tissues and organs.
Drug binding to plasma proteins influences the distribution; only free drug can access tissues.
Tissues and organs with higher blood flow receive higher drug concentrations.

Metabolism

Biotransformation, mainly in the liver, is the conversion of a drug to another form or to metabolites.
This process often makes the drug more water-soluble for excretion.
This conversion can sometimes be to a less-active or more toxic form.
The process can occur in other organs and tissues, not just the liver.

Elimination

Elimination is the removal of a drug from the body.
Excretion. Excretion primarily occurs via the kidneys (urine), but also from the liver (bile), and through sweat, feces, etc.
Renal function is vital in drug elimination, kidney failure can slow or stop drug removal, leading to toxicity

Factors Affecting Drug Absorption

Lipophilicity/hydrophilicity: lipophilic drugs cross membranes easily.
Ionization: the ionized form is more polar and less lipid-soluble.
pH: the environment affects drug ionization and thus its passage through membranes.

Factors Affecting Drug Distribution

Blood flow to tissues.
Plasma protein binding (only free drug can enter tissues).
Drug-tissue interactions.

Factors Affecting Drug Metabolism

Enzyme induction/inhibition (e.g., by drugs or environmental factors).
Genetic polymorphisms.
Age.
Gender.
Disease.
Diet

Factors Affecting Kidney Function

Renal disease, which can affect both glomerular filtration and tubular secretion.

Drug Transport

Solute carriers (SLCs) and ATP-binding cassette (ABC) transporters are membrane proteins that play a role in drug absorption, distribution, and excretion.
These transporters can be affected by drug-drug interactions

Bioavailability

Bioavailability is the fraction of the administered drug that enters the systemic circulation and is available to bind to receptors.
It's often expressed by the area under the concentration-time curve (AUC).
Important when assessing different routes of administration (IV, IM, oral).

Routes of Administration

Oral
Intravenous
Intramuscular
Subcutaneous
Topical
Others (inhalation, intra-articular etc)

Other important concepts:

Henderson-Hasselbalch equation. This equation reveals the relationship between the pH of the environment and the ionization.
First-pass metabolism. This is the metabolism of the drug by the liver after absorption from the gastrointestinal tract, resulting in a lower bioavailability.
Hepato-enterohepatic recirculation. This process can potentially prolong the presence of drugs in the body, especially the water-soluble drug metabolites and also the parent drug.
Phase I and Phase II reactions of metabolism.
Cytochromes p450. These enzymes play a key role in the biotransformation of drugs.
Clinical relevance. These are important considerations for drug dosages and patient health. (e.g., species-selective differences, drug and drug interactions)

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Description

Test your knowledge on pharmacology concepts related to drug interactions, absorption, and distribution in the body. This quiz covers key topics such as the effects of antimicrobial co-administration, the action of Warfarin, and the importance of lipophilicity in drug transport. Dive into these essential principles of drug metabolism and therapeutic effectiveness.