Development and evaluation of xyloglucan matrix release tabs contaning glipizide

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Pharmacodynamic Animation : full agonists, partial agonists, inverse agonists, competitive antagonists and irreversible antagonists.

 

Agonist dose response curve in the presence of competitive and irreversible antagonists

Some pharmacodynamic definitions related to the animation:

Full Agonists: Compounds that are able to elicit a maximal response following receptor occupation and activation.

Partial Agonists: Compounds that can activate receptors but are unable to elicit the maximal response of the receptor system.

Inverse agonist: an agent which binds to the same receptor binding-site as an agonist for that receptor and reverses constitutive activity of receptors. Inverse agonists exert the opposite pharmacological effect of a receptor agonist.

Competitive and Irreversible Pharmacologic Antagonists

Competitive antagonists are drugs that bind to the receptor in a reversible way without activating the effector system for that receptor. In the presence of a competitive antagonist, the log dose-response curve is shifted to higher doses (ie, horizontally to the right on the dose axis) but the same maximal effect is reached (Figure 2-5A).

In contrast, an irreversible antagonist causes a downward shift of the maximum, with no shift of the curve on the dose axis unless spare receptors are present (Figure 2-5B). The effects of competitive antagonists can be overcome by adding more agonist. Irreversible antagonists cannot be overcome by adding more agonist. Competitive antagonists increase the ED50; irreversible antagonists do not (unless spare receptors are present).

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Volume of Distribution

First, a video that analyzes the factors that affect drug distribution: protein binding, molecular weight and lipid solubility.

Authors: Nelson Caetano, Dr. Jef Bratberg. University of Rhode Island

A transcript of the explanatory text:

Unbound drug passes freely through blood vessels and is distributed into the rest of the body. Protein bound drug is trapped within the vessel and is therefore unable to reach its intended sight of action.
Small drug molecules can freely diffuse out of the blood vessel while large drug molecules are confined to the plasma. Heparin is a good example of a drug like this.
Lipid solubility of a drug is a major component in determining its distribution, particularly on the brain. The blood brain barrier prevents the crossing of polarized molecules from capillaries to brain neurons.

The slides below are part of a lecture I give about pharmacokinetics. I chose the slides that explain the meaning of the different values of volume of distribution.
A drug that has a volume of distribution near the plasma volume (e.g. 5 liters) is a drug distributed mainly in the intravascular space. A drug with a very high volume of distribution ( hundreds of liters) should guide us to think that is a drug that bind very strongly to a particular tissue.

Download PPT file: Volume of distribution

Recommended pharmacokinetics reading

Pocket Guide: Pharmacokinetics Made Easy (2009)

Basic Clinical Pharmacokinetics (2009)

Concepts in Clinical Pharmacokinetics (2010)

Clinical Pharmacokinetics, 4th Edition (2008)

Insulin secretion and sulfonylureas: mechanism of action

Sulfonylureas are the most widely prescribed drugs in the treatment of type II diabetes mellitus. The initial sulfonylureas were introduced nearly 50 years ago and were derivatives of the antibacterial sulfonamides.
The primary mechanism of action of the sulfonylureas is direct stimulation of insulin release from the pancreatic beta cells. In the presence of viable pancreatic Beta-cells, sulfonylureas enhance the release of endogenous insulin, thereby reducing blood glucose levels. At higher doses, these drugs also decrease hepatic glucose production, and the second-generation sulfonylureas may possess additional extrapancreatic effects that increase insulin sensitivity, though the clinical significance of these pharmacological effects is unclear.

Classification of sulfonylureas

First-generation Acetohexamide Tolbutamide Tolazamide Chlorpropamide	Second-generation Glyburide (Glibenclamide)Glipizide Glimepiride Glicazide Gliquidone

Mechanism of action on insulin secretion

In the basal state, the plasma membrane of the β cell is hyperpolarized, and the rate of insulin secretion from the cell is low. When glucose is available, it enters the cell via GLUT2 transporters in the plasma membrane and is metabolized to generate intracellular ATP. ATP binds to and inhibits the plasma membrane K+/ATP channel. Inhibition of the K+/ATP channel decreases plasma membrane K+ conductance; the resulting depolarization of the membrane activates voltage-gated Ca2+ channels and thereby stimulates an influx of Ca2+. Ca2+ mediates fusion of insulin-containing secretory vesicles with the plasma membrane, leading to insulin secretion.
The K+/ATP channel, an octamer composed of Kir6.2 and SUR1 subunits, is the target of several physiologic and pharmacologic regulators. ATP binds to and inhibits Kir6.2, while sulfonylureas bind to and inhibit SUR1; these agents promote insulin secretion.

Therapeutic uses, side effects and contraindications [2]

Sulfonylureas are used to control hyperglycemia in type 2 Diabetes mellitus affected patients who cannot achieve appropriate control with changes in diet alone. In all patients, continued dietary restrictions are essential to maximize the efficacy of the sulfonylureas.

The major adverse effect is hypoglycemia resulting from oversecretion of insulin; therefore, should be used cautiously in patients who are unable to recognize or respond to hypoglycemia


Contraindications to the use of these drugs include type 1 DM, pregnancy, lactation, and for the older preparations, significant hepatic or renal insufficiency.

Sources

[1] Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy, Second Edition
by David E. Golan.

[2] Goodman & Gilman’s The Pharmacological Basis of Therapeutics, 11 edition, by Laurence Brunton, John Lazo, and Keith Parker.

Benzodiazepines and GABA receptors: mechanism of action

Gamma amino butyric acid (GABA) is an inhibiting neurotransmitter that is present on human brains. As shown in the animation, gamma amino butyric acid promotes opening of a postsynaptic receptor, the GABA-A receptor.

This opening leads to a increased conductance to cloride ions, which produces membrane hiperpolarization, this induces a neuronal inhibition.

The binding of benzodiazepines to the GABA-A receptor increases the affinity of gamma amino butyric acid (GABA) and its receptor, thereby increasing the opening frecuency of GABA-A receptor.As a consequence of this, benzodiazepines potentiate GABAergic neurotransmission.

Drug list:

Some of the drugs included under the benzodiazepine class are:

• Alprazolam
• Diazepam
• Flurazepam
• Lorazepam
• Midazolam
• Oxazepam
• Prazepam
• Temazepam
• Triazolam

References:

• Modern Pharmacology with Clinical Applications, Sixth Edition by Charles Craig
• Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy, Second Edition
   by David E Golan

Mechanism of action : ACE inhibitors, Angiotensin II receptor blockers (ARBs) and the Renin Angiotensin Aldosterone System

Also, a diagram of the Renin Angiotensin Aldosterone System (RAAS System) physiology.

Drugs acting on the Renin Angiotensin Aldosterone System.

ACE Inhibitors.

List of agents

Sulfhydryl-containing agents

Captopril (Capoten), Zofenopril

Dicarboxylate-containing agents

Enalapril (Vasotec, Renitec)
Ramipril (Altace, Tritace, Ramace, Ramiwin)
Quinapril (Accupril)
Perindopril (Coversyl, Aceon)
Lisinopril (Lisodur, Lopril, Novatec, Prinivil, Zestril)
Benazepril (Lotensin)

Phosphonate-containing agents

Fosinopril (Monopril) is the only member of this group

Angiotensin II receptor blockers (ARBs)

Mode of action. Source: Wikipedia

These substances are AT1-receptor antagonists – that is, they block the activation of angiotensin II AT1 receptors. Blockade of AT1 receptors directly causes vasodilation, reduces secretion of vasopressin, reduces production and secretion of aldosterone, amongst other actions – the combined effect of which is reduction of blood pressure.

List of agents
Losartan (Cozaar)

Irbesartan ( Aprovel, Karvea, and Avapro)

Olmesartan (Benicar, Olmetec)

Candesartan (Blopress, Atacand, Amias, and Ratacand)

Valsartan (Diovan, Valtan, Valtan)

Recommended reading

• Cardiology Drug Guide 2010
• Drugs for the Heart: Expert Consult: Online and Print
• Clinical Cardiology Made Ridiculously Simple (Edition 3 – 2010 )

TRUTH and FACTS revealed

My main motto in writing this article is to built or strive for a Better INDIA...Better World !!

It is good to be influenced by a PERSON and follow him, but making HIM a GOD is a very foolish thing to do.

Now a Days, Many are cashing the believes of the innocent people.. It is a truth that there are nearly a thousands of PEOPLE who are fooling the other PEOPLE among them..

Who said that I will be BORN AGAIN as another AVATAR...??? No ONE !!
But one has announced that HE is the AVATAR of the Previous one !!
and the innocent people started believing the same.. made him a GOD-MAN !!

Not only the innocent common man, but many famous personalities started doing the same.. There is a REASON behind this story..
If a famous personality started following some GOD-MAN, automatically,, all the other common man get influenced by the same, and get started to follow the same !! This is a trick followed by most of the GOD-MANS now a days..

This GOD-MAN has already announced that I will be having another AVATAR in the coming Future !!

In the Coming future, If any body says that I'M THE AVATAR, that GOD-MAN SAID... people start believing him toooo.

I dont want to criticise or stabb some one, but the fact is this. I'm glad that many of the GOD-MANS do many CHARITY based services, apart from making people FOOL !! I support and appreciate to all those who do charity and help for the PEOPLE..

Since my Childhood, I used to see, many of my classmates talking about MAKARA JYOTHI in sabarimalai. I used to say alwayz that, Believe in GOD, but not in this foolish SHRINE's..
But no one of my friends agreed with me.. neither the Public..
But Now, all got revealed.. The Travancore Devaswom Board (TDB) itself told the Kerala High Court on April 25th 2011 Monday, that CELESTIAL LIGHT was actually a MAN-MADE , three months after a stampede killed 102 pilgrims there.

According to THE HOLY BIBLE, Nostradamus, and many more great Scholars.. At the End of the World, all the TRUTHS will be Revealed.. Now many have been already revealed.. Many more yet to be Revealed in the coming future..

Why We Celebrate Easter ????

CHILDREN WITH CANCER.... Save them..Love Them !!

Save Women & Respect Women !