What is the importance of DRC of drug?
6. The DRC of drug is useful to predict potency, efficacy & safety of drug. 1) Potency : The position of DRC on the axis is an index of drug potency.
What is dose response curve (DRC)?
Fig.1 : Dose response curve 6. The DRC of drug is useful to predict potency, efficacy & safety of drug. 1) Potency : The position of DRC on the axis is an index of drug potency.
What is the difference between DRC and efficacy?
The upper limit of DRC is the index of drug efficacy and refers to the maximal response that can be elicited by the drug, e.g. morphine produces a degree of analgesia not obtainable with any dose of aspirin—morphine is more efficacious than aspirin. Efficacy is a more decisive factor in the choice of a drug.
What is pharmacology?
June 14, 2017. Pharmacology is the study of drugs including their origins, history, uses, and properties. It mainly focuses on the actions of drugs on the body.
Dose Response Equation
As the dose-response curve is generally sigmoidal, it could be represented by a Hill equation.
Dose Response Curve Phases
A dose response curve consists of three phases. The first phase is when the concentration is still low enough that it is not able to initiate any responses, resulting in no observed effects. This phase is referred to as the threshold dose. Following the increase in drug concentration, an increase in the response is observed.
Effective vs Lethal Dose
Two important parameters in pharmacology can be obtained from the dose response curves. The first one is the effective dose (ED) or effective concentration (EC), which depicts the dose or concentration of a drug that is able to initiate biological responses.
What is the gap between the therapeutic effect DRC and the adverse effect DRC?
The gap between the therapeutic effect DRC and the adverse effect DRC defines the safety margin or the therapeutic index of a drug. In experimental animals, therapeutic index is often calculated as:
What is the upper limit of DRC?
The upper limit of DRC is the index of drug efficacy and refers to the maximal response that can be elicited by the drug , e.g. morphine produces a degree of analgesia not obtainable with any dose of aspirin—morphine is more efficacious than aspirin. Efficacy is a more decisive factor in the choice of a drug.
What is the difference between a steep and flat DRC?
A steep slope indicates that a moderate increase in dose will markedly increase the response (dose needs individualization), while a flat one implies that little increase in response will occur over a wide dose range (standard doses can be given to most patients). Hydralazine has a steep, while hydrochlorothiazide has a flat DRC of antihypertensive effect (Fig. 4.13).
Why is the dose response curve rectangular?
4.11). This is because drugreceptor interaction obeys law of mass action, accordingly—
Why is a drug so prominent at different concentrations?
The pharmacological basis of this phenomenon is not well understood, but may be due to dual or complex actions of the drug—different facets of which become prominent at different concentrations.
When should a drug be prescribed?
A drug should be prescribed only when the benefits outweigh the risks. However, riskbenefit ratio can hardly ever be accurately measured for each instance of drug use, because ‘risk’ is the probability of harm; and harm has to be qualified by its nature, quantum, timecourse (transient to lifelong) as well as the value that the patient attaches to it. None of these can be precisely ascertained. As such, the physician has to rely on data from use of drugs in large populations (pharmacoepidemiology) and his own experience of the drug and the patient.
Is the therapeutic range bounded by the dose that produces minimal therapeutic effect?
But this is irrelevant in the clinical set up where the therapeutic range is bounded by the dose which produces minimal therapeutic effect and the dose which produces maximal acceptable adverse effect (Fig. 4.15). Because of individual variability, the effective dose for some subjects may be toxic for others; defining the therapeutic range for many drugs is a challenging task. A drug may be capable of inducing a higher therapeutic response (have higher efficacy) but development of intolerable adverse effects may preclude use of higher doses, e.g. prednisolone in bronchial asthma.
What is the DRC of a drug?
6. The DRC of drug is useful to predict potency, efficacy & safety of drug. 1) Potency : The position of DRC on the axis is an index of drug potency. A DRC positioned rightward indicates lower potency .Drug A is more potent than drug B,since it produced intensity of response as drug B as much smaller doses.The relative potency is determined by comparing the dose of two agonists at which they produces half maximum response (EC50). eg.10mg of Morphine is equivalent 100mg of Pethidine to produce analgesia,hence morphine is 10 times more potent than pethidine.
What is the gap between the therapeutic effect DRC and the adverse effect DRC?
12. The gap between the therapeutic effect DRC & the adverse effect DRC defines therapeutic index of a drug. The therapeutic index gives a measure of safety margin of a drug. Median lethal dose Therapeutic index= Median effective dose Median effective dose (ED50) is the dose of a drug necessary to half of all population & median lethal dose is dose of a drug lethal to half of population.
What is the upper limit of DRC?
8. 2) Efficacy: The upper limit of DRC is the index of drug efficacy & refers to the maximal response that can be elicited by the drug ,eg .morphine produce a degree of analgesia not obtain with any dose of aspirin. Morphine is more efficacious than aspirin. Efficacy is a more decisive factor in the choice of the drug. Depending upon type of drug, both higher & lower efficacious drug is cleanically prefered.
What is a drug response curve?
"DRUG RESPONSE CURVE & THERAPEUTIC" it's a topic in which detail information about How Drug Response when taken in body & effect of various drugs on body with there Response Curve is Given .
How are dose and response related?
4. The dose and response is closely related to each other and this relationship is called as Dose response relationship. There is direct relationship between dose intensity of response of the curve, i.e.the intensity of response increases with the increase in dose. A typical curve showing the dose response relationship is called dose response curve (DRC).
What does DRC mean on the dose axis?
The position of DRC on the dose axis is the index of drug potency which refers to the amount of drug needed to produce a certain response. A DRC positioned rightward indicates lower potency.
What is the upper limit of DRC?
The upper limit of DRC is the index of drug efficacy and refers to the maximal response that can be elicited by the drug , e.g. morphine produces a degree of analgesia not obtainable with any dose of aspirin—morphine is more efficacious than aspirin. Efficacy is a more decisive factor in the choice of a drug.
What is the difference between a steep and flat DRC?
A steep slope indicates that a moderate increase in dose will markedly increase the response (dose needs individualization), while a flat one implies that little increase in response will occur over a wide dose range (standard doses can be given to most patients). Hydralazine has a steep, while hydrochlorothiazide has a flat DRC of antihypertensive effect (Fig. 4.13).
What is dose response graph?
Dose-response data are typically graphed with the dose or dose function (eg, log 10 dose) on the x-axis and the measured effect ( response) on the y-axis. Because a drug effect is a function of dose and time, such a graph depicts the dose-response relationship independent of time. Measured effects are frequently recorded as maximal at time of peak effect or under steady-state conditions (eg, during continuous IV infusion). Drug effects may be quantified at the level of molecule, cell, tissue, organ, organ system, or organism.
Is drug concentration linear or nonlinear?
However, response to concentration may be complex and is often nonlinear. The relationship between the drug dose, regardless of route used, and the drug concentration at the cellular level is even more complex (see Pharmacokinetics ).
What is the AUC of a drug?
The AUC is inversely proportional to the clearance of the drug. That is, the higher the clearance, the less time the drug spends in the systemic circulation and the faster the decline in the plasma drug concentration. Therefore, in such situations, the body exposure to the drug and the area under the concentration-time curve are smaller.
What does CL mean in pharmacology?
Apparent clearance (CL’): In some pharmacokinetic trials, the bioavailability of the studied drug is not known. The apparent clearance, resulting from the dose divided by the AUC, reflects the drug’s clearance that does not take into account the bioavailability of the drug.
What does C (0) mean?
C (0) = extrapolated plasma concentration at time 0
What is the clinical pharmacology of drugs?
Clinical Pharmacology: focuses on the therapeutic uses of drugs and the factors that may affect the efficacy of a drug, such as age, pregnancy, disease, and combination in use with other drugs. It is also concerned with bioavailability, which is the proportion of a drug dose that is actually absorbed by the body instead of just passing through.
What are the two branches of pharmacology?
Other areas in pharmacology that can involve both of the two main branches of pharmacodynamics and pharmacokinetics include: 1 Clinical Pharmacology: focuses on the therapeutic uses of drugs and the factors that may affect the efficacy of a drug, such as age, pregnancy, disease, and combination in use with other drugs. It is also concerned with bioavailability, which is the proportion of a drug dose that is actually absorbed by the body instead of just passing through. 2 Toxicology: focuses on the adverse effects that drugs may have on the body. It examines side effects not only from drugs given therapeutically but also on chemicals that a person may be exposed to in their household, occupation, or environment.
What is pharmacology lab?
Pharmacology work is lab-based. With a bachelor’s degree, one can work as a research technician in a laboratory. Further schooling leading to a master’s degree may lead to positions with more responsibility, such as lab manager or research assistant positions. A PhD is required to be in charge of a lab and design experiments. Labs may be located in universities (where teaching may also be required), pharmaceutical companies, commercial or government-funded research centers, or medical charities. Pharmacologists often specialize in a specific area such as neuropharmacology, cardiovascular pharmacology, or veterinary pharmacology.
What is the purpose of pharmacology?
It mainly focuses on the actions of drugs on the body. A drug is defined a substance that is used to treat, cure, or prevent a disease or otherwise enhance physical or mental health. The word pharmacology comes from the Greek words pharmakos, meaning medicine or drug, and logos, meaning study.
What classes do you take in pharmacology?
Pharmacology majors then take upper-level courses more specific to the field, such as biochemical pharmacology, cellular biology, developmental biology, and neurobiology. Of course, biology majors who are not going into the field of pharmacology may also take some of these upper-level courses as well. If one is interested in becoming ...
What is the compound that is used to treat parasympathetic nervous system?
There, he studied chloroform, which was used as an anesthetic, chloral hydrate, a sedative and hypnotic, and muscarine, a compound isolated from the mushroom Amanita muscaria that stimulates the parasympathetic nervous system and has been used to treat various diseases such as glaucoma.
Which organ filters out drugs from the body?
A drug may be administered orally, parenterally (such as through an injection), or intravenously (into the bloodstream, through an IV). The kidney is the main organ that filters out drugs from the body, but the lungs and sweat glands also have minor roles.