Centrally acting muscle relaxants

Thursday, December 16, 2010


 

1. Mephenesin group

           Mephenesin
           Carisoprodol
           Chlorzoxazone
           Chlormezamone
           Methocarbamol

2 .Benzodiazepines

           Diazepam and others

3. GABA derivative
       
         Baclofen

4. Central alpha 2 agonists
         Tizanidine

Local anesthetics


1. Injectable

A. Low Potency, Short Duration Of Action

Procaine
Chlo-procaine

B. Intermediate potency and duration

Lignocaine (Lidocaine)
Prilocaine

C. High potency, long duration

Tetracaine (Amethocaine)
Cinchocaine
Bupivacaine
Ropivacaine


11. Surface anesthetics

A. Soluble

Cocaine
Lignocaine
Tetracaine


B. Insoluble

Benzocaine
Butamben
Oxethazaine

Parasympathomimetic drugs


1. Choline esters

Acetyl choline
Methacholine  - 10-30 mg , s/c
Carbachol- 0.2 – 0.5mg s/c , or 1-4mg , orally
Bethanechol- 2.5 mg s/c, 5 -30 mg orally


2. Naturally occurring  alkaloids

Polocarpine
Muscarine
Arecholine


3. A . Cholinesterase inhibitors

Physostigmine
Neostigmine
Pyrodostigmine
Benzpyrinium
Ambenonium
Edrophonium
Demecarium

 3. B Cholinesterase inhibitors (irreversible ) or organophosphorus
   compounds
 
DFP –(Di-iso-propyl fluorophosphate)
HETP- (Hexa ethyl tetra phosphate)
TEPP – (Tetra ethyl pyrophosphate)
OMPA – Octa methyl pyrophosphoramide)

Sympathomimetic drugs


 

Classification as per their site and mode of action

1.Alpha receptors

Noradrenalin
Mephentermine
Metarminol
Methoxamine
Phenylephrine

2. Beta receptor
Isoprenaline
Isoxsuprine
Nylidrine

3. Acting on both alpha and beta receptor

Adrenaline
Ephedrine
Amphetamine

Bile secretion



Composition of Bile

Water  - 97.5%

Solids -  2.5%

Solids contains


Organic substances                          - Bile salts
                                                            Bile pigments
                                                            Cholesteros
                                                            Fatty acids
                                                            Lecithin
                                                            Mucin


In organic substances                          Sodium
                                                            Potassium
                                                            Calcium
                                                            Chlorides
                                                            Bicarbonates
 

Formation of biles

Bile is produced continuously y by hepatocytes

Bile drains into the hepatic ducts and is stored in the gallbladder for subsequent release

Choleretic agents increase the formation of bile


Bile is formed by the following process


Primary acids

Ex – Cholic acid and chenodeoxycholic acid are synthesized from cholesterol  by hepatocytes


Secondary bile acids

In the intestine , bacteria convert a portion of each of the primary bile acids to secondary bile acids (deoxycholic acid and lithocholic acid)

Synthesis of new bile acids occurs as needed , to replace bile acids that are excreted in the feces

The bile acids are conjugated with glycine or taurine to form their respective bile salts

Ex – Taurocholic acid is cholic acid conjugated with taurine


Electrolytes and H2O are added to the bile

During the interdigestive period m the gallbladder is relaxed the sphincter of Oddi is closed and the gallbladder fills with bile

The bile is concentrated in the gallbladder as a result of isosmotic absorption of solutes and H2O

 Contraction of gallbladder

CCK

It is released in response to small peptides and fatty acids in the duodenum
It tells the gallbladder that bile is needed to emulsify and absorb lipids in the duodenum
It causes contraction of the gallbladder and relaxation of the sphincter of Oddi

 Ach

It causes contraction of the gallbladder
 
Function of bile

1.Digestive function

2. Absorptive functions

3. Excretory function

Bile pigments are the major excretory products of the bile

The other substances excreted in bile are             
Heavy metals like copper and iron
Some bacteria like typhoid
 Some toxins
Cholesterol
Lecithin

4. Laxative action

5. Antiseptic action

Bile inhibits the growth of certain bacteria in the lumen of intestine by its natural
detergent action

6. Lubrication function

The mucin in bile acts as a lubricant for the chime in  intestine

7.Maintenance of PH in GIT

It is highly alkaline, it neutralizes the acid chime which enters the intestine from stomach.
The optimum PH is maintained for the action of digestive enzymes