Pharmacology Chapter on Bioavailability

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The proportion of an administered drug that reaches the systemic circulation unchanged.

Increased first-pass metabolism means a higher proportion of the drug is broken down in the liver before it reaches the systemic circulation.

A drug's lipid solubility determines its ability to cross cell membranes.

The dosage formulation greatly influences how a drug is absorbed into the body.

The pKa of a drug determines its ionization state, which affects its absorption and distribution.

The interval between doses should be based on the half-life of the drug to maintain a steady concentration in the body.

Prolonging drug action is about making the drug last longer in the body.

Induction of microsomal enzymes can lead to faster drug metabolism, thereby shortening its duration of action.

Altering drug formulation can change how the drug is absorbed, distributed, and eliminated, ultimately affecting its action in the body.

Two drugs may compete for the same receptor site, altering their efficacy or effects.

The initial breakdown of a drug in the body, primarily by enzymes in the liver.

Drugs that increase the activity of liver enzymes, leading to faster metabolism of other drugs.

Drugs bind to specific targets like enzymes, receptors, or ion channels to exert their effects.

The relative amount of a drug needed to produce a desired effect.

The maximum effect that a drug can produce, regardless of the dose.

Drugs with a narrow therapeutic index (TI) have a small margin between the effective dose and the toxic dose.

A graph that shows the relationship between the dose of a drug and the magnitude of its effect.

These drugs have a high risk of toxicity, especially with small dose increases.

Drugs taken orally are absorbed through the digestive system and work by influencing the body's processes. They are commonly used for treating various conditions.

Paracetamol, insulin, heparin, nitroglycerin, and ampicillin are all commonly used drugs in healthcare.

Essential drugs are a carefully selected group of medicines that satisfy the priority healthcare needs of the majority of the population. They are designed to be safe, effective, and affordable.

Drugs work by interacting with specific targets in the body. These targets can include enzymes, hormones, receptors, plasma proteins, or ion channels. This interaction leads to a change in the body's function.

Second messengers are molecules inside cells that transmit signals from the outside to the inside, triggering a cascade of events. They play a crucial role in how drugs exert their effects.

Bioavailability reflects the extent to which an ingested drug actually reaches the bloodstream and has an effect. Factors like the route of administration, metabolism, and absorption play a role.

Oral drug administration can be safe, cheaper, and convenient. The drug travels through the digestive system and enters the bloodstream.

The first-pass effect is the metabolism of a drug by the liver before it can reach the bloodstream. This can reduce the amount of drug available to exert its effect.

Beta-blockers are a class of drugs that block the effects of adrenaline (epinephrine) and noradrenaline (norepinephrine) at beta-adrenergic receptors in the heart, blood vessels, and lungs.

Peripherally acting muscle relaxants primarily affect skeletal muscles, unlike centrally acting ones which also affect the central nervous system.

Atropine is a drug that blocks the action of acetylcholine, a neurotransmitter involved in various bodily functions. Its effects include dilated pupils, increased heart rate, dry mouth, and difficulty urinating.

Cholinergic stimulation refers to the activation of receptors that respond to acetylcholine. This neurotransmitter is involved in various processes, including muscle contraction, glandular secretion, and heart rate.

Muscarinic receptors are a type of cholinergic receptor found in various organs, including the heart, smooth muscle, and glands. Acetylcholine acting on these receptors can cause bronchoconstriction, increased lacrimation, and miosis.

Glaucoma is an eye disease characterized by increased pressure inside the eye. Drugs like Latanoprost and Timolol reduce this pressure by affecting either the production or drainage of fluid within the eye.

Local anesthetics are drugs that block the conduction of nerve impulses, preventing pain signals from reaching the brain. They are commonly used during surgery and dental procedures.

Propofol, Halothane, and Nitrous Oxide are all used for general anesthesia but Ketamine is a dissociative anesthetic and Oxygen is a respiratory gas.

Oxidation, Hydrolysis, and Reduction are common phase 1 reactions in drug metabolism. Acetylation and Glucoronide conjugation are phase 2 reactions - conjugation.

Chloramphenicol, Cimetidine, and Phenobarbitone are known microsomal enzyme inhibitors. Rifampicin is an inducer, and Ciprofloxacin is not directly known for inhibiting microsomal enzymes.

Barbiturates, Paracetamol, and Digoxin have a low therapeutic index, meaning a small difference between therapeutic dose and toxic dose.

Vasoconstriction can prolong drug action by slowing down absorption and distribution, delaying excretion also prolongs drug action, altering drug formulation can change absorption and distribution, and promoting drug metabolism can decrease drug action.

Pharmacodynamics is the study of drug action on the body. It includes receptors, dose-response, tolerance, but not absorption or elimination. Absorption and elimination are part of pharmacokinetics.

Bioavailability is the extent and rate at which a drug reaches the systemic circulation. It is dependent on the rate of absorption, the route of administration, and first-pass metabolism.

A drug's bioavailability is dependent on the rate of absorption and the first-pass metabolism. It is not directly dependent on the drug's half-life, volume of distribution, clearance, or the route of administration.

Tricyclic antidepressants are a class of medications used to treat depression and anxiety.

Commonly used antidepressant drugs include sertraline, amitriptyline, and paroxetine. These medications work to elevate mood and combat symptoms of depression.

Propranolol, pizotifen, and ergotamine are used to prevent migraines. These medications work by reducing the frequency and severity of migraine attacks.

Mydriatic drugs, such as atropine, tropicamide, and cyclopentolate, are used to dilate the pupils of the eyes. This dilation can help with eye examinations and certain eye surgeries.

Glaucoma is a serious condition that damages the optic nerve in the eye. Drugs like physostigmine, timolol, and acetazolamide are used to treat this condition.

Some antihypertensives not safe in pregnancy include lisinopril, losartan, and olmesartan. These medications can pose potential risks to the developing baby.

Hydrochlorothiazide is an example of a diuretic that helps lower blood pressure by reducing body fluid volume. However, it should generally be avoided during pregnancy.

Antihypertensives that can be used safely in pregnancy include a-methyldopa, nifedipine, and labetalol. These medications have been shown to be safe for both mother and baby.

Drugs that have proven survival benefits in heart failure patients include beta-blockers, ACE inhibitors, digoxin, and spironolactone. These medications help to strengthen the heart and improve overall function.

The following medications prolong the QT interval on an electrocardiogram (ECG): Quinidine, disopyramide, phenytoin, and amitriptyline. This can increase the risk of developing certain heart rhythm abnormalities.

Examples of drugs that can cause reflex tachycardia include noradrenaline, dopamine, and glyceryl trinitrate. This occurs when the heart rate increases as a compensatory response to a decrease in blood pressure.

ACE inhibitors, such as lisinopril and enalapril, work to lower blood pressure. They primarily reduce afterload, which is the resistance the heart experiences as it pumps blood.

ACE inhibitors are contraindicated in pregnancy, bilateral renal artery stenosis, and certain other conditions. It is important to consult with a doctor before taking these medications if you have any underlying health issues.

Nitroglycerin is a vasodilator commonly used for the treatment of angina pectoris. When taken, it can lead to side effects such as hypotension (low blood pressure) and headache.

Nitroglycerin is used to treat angina pectoris by reducing both preload and afterload, thus easing the strain on the heart. This can improve blood flow and reduce pain.