Chloramphenicol

2013-11-22T11:54:09Z

Sknight: /* Introduction */

[[Image: Chloramphenicol.png|thumb|right|250px|The 3D Structure of Chloramphenicol]]
==Introduction==
Chloramphenicol orginates from cultures of ''Streptomyces'' and was one of the first antibiotics to be synthetically mass-produced. It is a dichloracetic acid derivative. Its analogues florfenicol and thiamphenicol are discussed at the bottom of the page.

==Mechanism of Action==
Chloramphenicol works by inhibiting the transpeptidation of the peptide chain, during protein synthesis on the ribosomes. This will limit the growth and replication of bacteria but will not kill the bacteria so is a '''bacteriostatic''' antibiotic.

==Spectrum of Activity==
*It is a broad spectrum antibiotic active against most gram-positives, many gram-negatives and all anaerobes. It is also active against rickettsia and chlamydophilia.
*''Pseudomonas'' and mycobacteria species are resistant.

==Pharmacokinetic Considerations==
They are very lipophilic neutral small molecules, which are orally active and have a very wide volume of distribution. It is thus capable of penetrating cell membranes and will enter the CSF. It is eliminated in the liver via hepatic metabolism with only 10% being excreted in the urine unchanged. The half-life varies between each species and also with age of the animal.

==Side Effects and Contraindications==
* A reversible suppression of haematopoiesis occurs in cats when recieving high doses. It's use in cats should be limited to seven days.
* Myocardial depression has been noticed following intravenous administration.
* If it is given per os, dogs and cats often have gastrointestinal irritation.
* In man a fatal aplastic anaemia can occur, this has had severe implications on the veterinary world. In the EU it is now '''banned in all food producing animals in all of its forms''' (ie has no safe withdrawal period) to ensure it doesn't enter the food chain. The only licensed veterinary products are currently topical eye medication and off-shelf use of human oral and parenteral products in non-food producing animals.

==Florfenicol and Thiamphenicol==
These are both analogues of chloramphenicol with similar antibacterial activity. With these a higher percentage of drug is excreted unchanged in the urine.

More importantly they aren't associated with aplastic anaemia in man and so are authorised to be used in food-producing animals.

[[Category:WikiDrugs]]

The Formation of the Filtrate by the Glomerular Apparatus - Renal Flash Cards - Anatomy & Physiology

2010-11-16T13:47:01Z

Sknight:

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|linkpage =Urine Production - Renal Flash Cards - Anatomy & Physiology
|linktext =URINE PRODUCTION - RENAL FLASH CARDS
|maplink = Urinary System (Content Map) - Anatomy & Physiology
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'''Use the mouse to highlight the answers. They are written in white.'''

<TABLE BORDER="2" BORDERCOLOR="#6600FF" CELLPADDING="2" CELLSPACING="2" WIDTH="80%">
<TR>
<TD>'''Question'''</TD>
<TD>'''Answer'''</TD>
<TD>'''Link'''</TD>
</TR>
<TR>
<TD>What are the three layers of glomerular filtration barrier?</TD>
<TD>

* Fenestrated Capillary Endothelium
* Glomerular Basement Membrane
* Podocytes</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Glomerular Filtration| Link]]</TD>
</TR>
<TR>
<TD>Which of the three layers is the major barrier to protein?</TD>
<TD>

Glomerular Basement Membrane
</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Glomerular Basement Membrane|Link]]</TD>
</TR>
<TR>
<TD>Which Factors Determine Selective Filtration?</TD>
<TD>

* Hydrostatic pressure
* Molecular size
* Electrical charge
* Protein binding
* Molecular configuration
* Rigidity</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Factors Which Determine Selective Filtration|Link]]</TD>
</TR>
<TR>
<TD>Substances which are filtered at the same levels as plasma are described at being filtered at what level?</TD>
<TD>

Isotonic</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Composition of Filtrate|Link]]</TD>
</TR>
<TR>
<TD>Define Glomerular Filtration Rate.</TD>
<TD>
The glomerular filtration or GFR is the amount of fluid filtered from the capillaries into the Bowmans capsule per unit time.</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Glomerular Filtration Rate|Link]]</TD>
</TR>
<TR>
<TD>By which formula can GFR be expressed?</TD>
<TD>
GFR = Kf x net filtration pressure</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Glomerular Filtration Rate|Link]]</TD>
</TR>
<TR>
<TD>What determines renal blood flow and capillary hydrostatic pressure?</TD>
<TD>
Arterial blood pressure coupled with the contraction of both the afferent and efferent arterioles</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Regulation of Renal Blood Flow and Capillary Hydrostatic Pressure|Link]]</TD>
</TR>
<TR>
<TD>Why is it important that the constriction of the afferent and efferant arterioles changes with blood pressure?</TD>
<TD>
To maintain renal blood flow</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Regulation of Renal Blood Flow and Capillary Hydrostatic Pressure|Link]]</TD>
</TR>
<TR>
<TD>What effect does contracting the afferant arteriole have on filtration pressure?</TD>
<TD>
Reduces filtration pressure</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Constriction of the Afferent and Efferent Arterioles|Link]]</TD>
</TR>
<TR>
<TD>What are the two mechanisms for pressure autoregulation?</TD>
<TD>

* The Myogenic Response
* Tubuloglomerular Feedback</TD>
<TD>[[Autoregulation of GFR - Anatomy and Physiology#Pressure Autoregulation|Link]]</TD>
</TR>
<TR>
<TD>Which mechanism works by responding to increased stretch in the arterioles by constricting them to a smaller diameter?</TD>
<TD>
The Myogenic Response</TD>
<TD>[[Autoregulation of GFR - Anatomy and Physiology#Myogenic Response|Link]]</TD>
</TR>
<TR>
<TD>Which structure in the wall of the distal tubule detects an increase in NaCl when blood pressure increases?</TD>
<TD>
The Macula Densa</TD>
<TD>[[Reabsorption and Secretion Along the Distal Tubule and Collecting Duct - Anatomy & Physiology#Juxtaglomerular Apparatus|Link]]</TD>
</TR>
<TR>
<TD>What is the effect of increased sympathetic activity on the kidneys?</TD>
<TD>

* Reduced renal blood flow
* Small decrease in excreted waste
* Increased conservation of water and sodium</TD>
<TD>[[Sympathetic Nervous System effect on Glomerular Filtration Rate|Link]]</TD>
</TR>
<TR>
<TD>What is Renal Clearance?</TD>
<TD>

Renal clearance is the ability of the kidney to remove a compound from the blood</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Renal Clearance|Link]]</TD>
</TR>
<TR>
<TD>What other methods of clearance from the body apart from renal are there?</TD>
<TD>

* Biliary
* Pulmonary
* Salivary </TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Renal Clearance|Link]]</TD>
</TR>
<TR>
<TD>For the renal clearance of a substance to represent the GFR which two things must not happen to it as it moves along the nephron?</TD>
<TD>

It must not be reabsorbed or further secreted </TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Renal Clearance and GFR|Link]]</TD>
</TR>
<TR>
<TD>Name three compounds which can be used to measure GFR from Renal clearance.</TD>
<TD>

* Inulin
* Creatinine
* Urea</TD>
<TD>[[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Determination of GFR from Renal Clearance|Link]]</TD>
</TR>
</table>

[[Category:Urinary System]]

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Chloramphenicol

The Formation of the Filtrate by the Glomerular Apparatus - Renal Flash Cards - Anatomy & Physiology