Nitrous Oxide (N2O)

MAC 100%, blood/gas solubility ratio 0.47
- An inorganic gas., low solubility in blood, but greater solubility than N2
- Inflammable, but does support combustion.
- Excreted primarily unchanged through the lungs.
- It provides amnesia and analgesia when administered alone.
- Does not produce muscular relaxation.
- Less depressant to both the cardiovascular system and respiratory system than most of the other inhalational anesthetics.
- Lack of potency and tendency to produce anoxia are its primary limitations.
- The major benefit of nitrous oxide is its ability to reduce the amount of the secondary anesthetic agent that is necessary to reach a specified level of anesthesia.

Roxithromycin

It is used to treat respiratory tract, urinary and soft tissue infections. Roxithromycin is derived from erythromycin, containing the same 14-membered lactone ring. However, an N-oxime side chain is attached to the lactone ring.

Roxithromycin has similar antimicrobial spectrum as erythromycin, but is more effective against certain gram-negative bacteria, particularly Legionella pneumophilae.

When taken before a meal, roxithromycin is very rapidly absorbed, and diffused into most tissues and Phagocytes Only a small portion of roxithromycin is metabolised. Most of roxithromycin is secreted unchanged into the bile and some in expired air

Cephalosporins

Produced semisynthetically by chemical attachment of side chains to 7-aminocephalosporanic acid. Same mode of action , same resistance mech. 
But tend to be more resistant than penicillins to certain beta –lactamases .

GENERATION BASED ON :
-- BACTERIAL SUSCEPTIBILITY PATTERNS
-- RESISTANCE TO BETA –LACTAMASES
--NOT EFFECTIVE AGAINST -MRSA , L. MONOCYTOGENES , C. DIFFICLE , ENTEROCOCCI

First Generation 

Parentral

- CEPHALOTHIN
- CEFAZOLIN

Oral

- CEPHALEXIN
- CEPHRADINE
- CEFADROXIL

Second Generation

Parentral

CEFUROXIME
CEFOXITIN

Oral

CEFACLOR
CEFUROXIME AXETIL

Third Generation

Parentral

CEFOTAXIME 
CEFTIZOXIME
CEFTRIAXONE 
CEFTAZIDIME
CEFOPERAZONE

Oral 

CEFIXIME 
CEFPODOXIME
CEFDINIR 
CEFTIBUTEN

Fourth Generation

Parentral

CEFEPIME
CEFPIROME

Antiemetics

 Antiemetic drugs are generally more effective in prophylaxis than treatment. Most antiemetic agents relieve nausea and vomiting by acting on the vomiting centre, dopamine receptors, chemoreceptors trigger zone (CTZ), cerebral cortex, vestibular apparatus, or a combination of these.
 
 Drugs used in the treatment of nausea and vomiting belong to several different groups. These include:
 
1. Phenothiazines, such as chlorpromazine, act on CTZ and vomiting centre, block dopamine receptors, are effective in preventing or treating nausea and vomiting induced by drugs, radiation therapy, surgery and most other stimuli (e.g. pregnancy).
They are generally ineffective in motion sickness.
Droperidol had been used most often for sedation in endoscopy and surgery, usually in combination with opioids or benzodiazepines

2. Antihistamines such as promethazine and Dimenhyrinate are especially effective in prevention and treatment of motion.

3. Metoclopramide has both central and peripheral antiemetic effects. Centrally, it antagonizes the action of dopamine. Peripherally metoclopramide stimulates the release of acetylcholine, which in turn, increases the rate of gastric. It has similar indications to those of chlorpromazine.

4. Scopolamine, an anticholinergic drug, is very effective in reliving nausea & vomiting associated with motion sickness.

5. Ondansetron, a serotonin antagonist, is effective in controlling chemical-induced vomiting and nausea such those induced by anticancer drugs. 

6. Benzodiazepines: The antiemetic potency of lorazepam and alprazolam is low. Their beneficial effects may be due to their sedative, anxiolytic, and amnesic properties

CARDIAC GLYCOSIDES

Cardiac glycosides (Digitalis)

Digoxin

Digitoxin

Sympathomimetics

Dobutamine

Dopamine

Vasodilators

α-blockers (prazosin)

Nitroprusside

ACE-inhibitors (captopril)

Pharmacology of Cardiac Glycosides

1. Positive inotropic effect (as a result of increase  C.O., the symptoms of CHF subside).

2. Effects on other cardiac parameters

1) Excitability

2) Conduction Velocity; slightly increased in atria & ventricle/significantly

reduced in conducting tissue esp. A-V node and His-Purkinje System

3) Refractory Period; slightly ^ in atria & nodal tissue/slightly v in ventricles

4) Automaticity; can be greatly augmented - of particular concern in ventricle

3. Heart Rate

-Decrease due to 1) vagal stimulation and 2) in the situation of CHF, due to improved hemodynamics

4 Blood Pressure

-In CHF, not of much consequence. Changes are generally secondary to improved cardiac performance.

-In the absence of CHF, some evidence for a direct increase  in PVR due to vasoconstriction.

5. Diuresis

-Due primarily to increase in  renal blood flow as a consequence of positive inotropic effect (increase CO etc.) Possibly some slight direct diuretic effect.

 Mechanism of Action of Cardiac Glycosides

Associated with an interaction with membrane-bound Na+-K+ ATPase (Na-K pump).

Clinical ramifications of an interaction of cardiac glycosides with the Na⁺ K pump.

I. Increase levels of Ca⁺⁺, Increase therapeutic and toxic effects of cardiac glycosides

II. Decrease levels of K⁺ , Increase toxic effects of cardiac glycosides

Therapeutic Uses of Cardiac Glycosides

• CHF
• CHF accompanied by atrial fibrillation
• Supraventricular arrhythmias

Structure of the CNS 

The CNS is a highly complex tissue that controls all of the body activities and serves as a processing center that links the body to the outside world. 
It is an assembly of interrelated “parts”and “systems”that regulate their own and each other’s activity. 

1-Brain                                  
2-Spinal cord 

The brain is formed of 3 main parts: 

I. The forebrain
• cerebrum
• thalamus
• hypothalamus

II. The midbrain
III. The hindbrain
• cerebellum
• pons
• medulla oblongata

Different Parts of the Different Parts of the CNS & their functions CNS & their functions
The cerebrum(cerebral hemispheres):
It constitutes the largest division of the brain. 
The outer layer of the cerebrum is known as the “cerebral cortex”. 

The cerebral cortex is divided into different functional areas: 
1.Motorareas(voluntary movements) 
2.Sensoryareas(sensation) 
3.Associationareas(higher mental activities   as consciousness, memory, and behavior).

Deep in the cerebral hemispheres are located the “basal ganglia” which include the “corpus striatum”& “substantianigra”. 

The basal gangliaplay an important role in the control of “motor”activities

The thalamus:

It functions as a sensory integrating center for well-being and malaise. 
It receives the sensory impulses from all parts of the body and relays them to specific areas of the cerebral cortex.

The hypothalamus:

It serves as a control center for the entire autonomic nervous system. 
It regulates blood pressure, body temperature, water balance, metabolism, and secretions of the anterior pituitary gland.

The mid-brain: 

It serves as a “bridge”area which connects the cerebrum to the cerebellum and pons. 
It is concerned with “motor coordination”.

The cerebellum:

It plays an important role in maintaining the appropriate bodyposture& equilibrium.

The pons:

It bridges the cerebellum to the medulla oblongata. 
The “locus ceruleus”is one of the important areas of the pons.

The medulla oblongata:
 
It serves as an organ of conduction for the passage of impulses between the brain and spinal cord. 
It contains important centers: 
• cardioinhibitory 
• vasomotor 
• respiratory 
• vomiting(chemoreceptor trigger zone, CTZ).

The spinal cord:

It is a cylindrical mass of nerve cells that extends from the end of the medulla oblongata to the lower lumbar vertebrae. 
Impulses flow from and to the brain through descending and ascending tracts of the spinal cord.