What Causes Tachyphylaxis?


Tachyphylaxis is the loss of response of tissues following repeated or continuous administration of a drug.

What does drug dependence and tachyphylaxis mean?

From Wikipedia, the free encyclopedia. Tachyphylaxis (Greek ταχύς, tachys, “rapid”, and φύλαξις, phylaxis, “protection”) is a medical term describing an acute, sudden decrease in response to a drug after its administration; i.e. a rapid and short-term onset of drug tolerance.

What do you mean by tachyphylaxis?

Tachyphylaxis is the continued or repeated exposure to a drug that may lead to a weakened pharmacological response. This presumed to be a consequence of diminished receptor sensitivity in response to consistent stimulation by a drug agonist, which produces a diminished pharmacological response in consequence.

How can tachyphylaxis be prevented?

Tolerance, termed tachyphylaxis, develops quickly to the effects of nitrates. To prevent tolerance from occurring there should be a nitrate-free interval (at least 12 hours) during each 24-hour period (typically overnight).

Which drug causes tachyphylaxis?

Over-the-counter ophthalmic decongestant drops, such as Visine (Pfizer), are another category of drugs that induce tachyphylaxis. In particular, these medications contain alpha-adrenergic amines—such as tetrahydrozoline, naphazoline or phenylephrine—that act as vasoconstrictors.

What is an example of tachyphylaxis?

Examples of tachyphylaxis include: Indirect sympathomimetics: ephedrine and metaraminol both displace noradrenaline from storage vesicles; tachyphylaxis results from repeated administration because noradrenaline is depleted from said vesicles.

What is tachyphylaxis vs tolerance?

The term tachyphylaxis is used to describe desensitization that occurs very rapidly, sometimes with the initial dose. The term tolerance is conventionally used to describe a more gradual loss of response to a drug that occurs over days or weeks.

Which type of toxic reaction takes place when a drug is taken continuously or repeatedly?

Tolerance is a person’s diminished response to a drug, which occurs when the drug is used repeatedly and the body adapts to the continued presence of the drug.

How is Tachyphylaxis treated?


  1. Increasing the current antidepressant dose. …
  2. Drug holidays or decreasing the current antidepressant dose. …
  3. Changing antidepressant drugs (to the same mechanism or a different mechanism of action). …
  4. Augmentation strategies for ADT tachyphylaxis.

What the body does to drug?

Pharmacokinetics, sometimes described as what the body does to a drug, refers to the movement of drug into, through, and out of the body—the time course of its absorption.

Why does ephedrine cause Tachyphylaxis?

When given in repeated doses, tachyphylaxis occurs, probably because of depleted norepinephrine stores. Ephedrine causes an increase in systolic, diastolic, and MAPs. It increases myocardial contractility, heart rate, and cardiac output (see Table 25.1).

What is Prozac poop out?

From Wikipedia, the free encyclopedia. Antidepressant treatment tachyphylaxis (ADT tachyphylaxis), also known as Prozac poop-out, is a medical condition in which progressive or acute tolerance effects are seen following chronic administration of a drug.

How can you prevent drug tolerance?

How can you prevent growing a tolerance?

  1. Consider non-pharmaceutical treatments. Medication is vital for many patients, but it’s not the only treatment available. …
  2. Keep a journal. Especially when recovering from an injury, it can be hard to recall how you’ve progressed. …
  3. Dispose of unnecessary prescriptions.

What does it mean when a drug is resistant?

Drug resistance: The ability of bacteria and other microorganisms to withstand a drug that once stalled them or killed them.

What does term bioavailability mean?

The ability of a drug or other substance to be absorbed and used by the body. Orally bioavailable means that a drug or other substance that is taken by mouth can be absorbed and used by the body.

Why does desensitization occur?

Homologous desensitization occurs when a receptor decreases its response to an agonist at high concentration. It is a process through which, after prolonged agonist exposure, the receptor is uncoupled from its signaling cascade and thus the cellular effect of receptor activation is attenuated.

What is acute tolerance?

Acute tolerance can be defined as a decrease in response to alcohol within a single exposure to the drug, which occurs independently of changes in blood alcohol concentrations (BACs).

What is cumulation in pharmacology?

Quick Reference. The process by which blood levels of a drug build-up, thereby increasing its therapeutic and toxic effects. If drug dosage exceeds the elimination rate, the drug will cumulate.

What is a pharmacodynamic drug?

Abstract. Pharmacodynamic drug-drug interactions (DDIs) occur when the pharmacological effect of one drug is altered by that of another drug in a combination regimen. DDIs often are classified as synergistic, additive, or antagonistic in nature, albeit these terms are frequently misused.

How drugs are transported through diffusion and Symport system?

Symporters are also termed cotransporters. They cotransport two or more different molecules or ions across the membrane. Typically, the ions will move down the electrochemical gradient through facilitated diffusion coupled with a uniporter, allowing the drug molecule to move against the concentration gradient.

Does nitroglycerin cause Tachyphylaxis?

For example, since nitroglycerine demonstrates tachyphylaxis, you should wait for durations of time (i.e., drug-free intervals) between doses to allow patients to remain sensitive to the drug effects. Studying tachyphylaxis is important in establishing proper dosing.

Does scopolamine cross the blood brain barrier?

Scopolamine crosses the blood–brain barrier and exerts its action in the CTZ. … Side effects of scopolamine include drowsiness, disorientation, confusion, dizziness, blurred vision, dry mouth, urinary retention, and pupil dilation. All of these side effects are related to the blockade of ACh receptors in the CTZ.

What is idiosyncratic adverse drug reaction?

Abstract. Idiosyncratic drug reactions may be defined as adverse effects that cannot be explained by the known mechanisms of action of the offending agent, do not occur at any dose in most patients, and develop mostly unpredictably in susceptible individuals only.


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