Antidiarrheal

 Antidiarrheal drugs may be given to relieve the symptom (non-specific therapy) or may be given to treat the underlying cause of the symptom (specific therapy). 

Ι. Drugs used for the symptomatic (non-specific) treatment of diarrhoea include: 

• Opiates and opiate derivatives are the most effective (such as morphine), but it is not used because of potentially serious adverse effects. Other agents, such as diphenoxylate and loperamide, are commonly used.

• Adsorbent – demulcent products such as kaolin – pectin preparation may be included in antidiarrheal preparations. Unfortunately, they may adsorb nutrients and other drugs, including the antidiarrheal agents if given concurrently.

• Anticholinergic agents e.g. atropine is occasionally used to decrease abdominal cramping and pain associated with diarrhoea.

ΙΙ. Specific therapy may include the use of antibacterial agents that are recommended for use in carefully selected cases of bacterial enteritis. For example, severe diarrhoea by salmonella, shigella, campylobacter and clostridia species can be treated by antibiotics (ampicillin, chloramphenicol, co-trimoxazole). 

Ketoprofen

It acts by inhibiting the body's production of prostaglandin.

Distal (Potassium Sparing) Diuretics

Agents:

spironolactone
triamterene

Mechanism of action

Inhibition of Na/K exchange at aldosterone dependent distal tubular site

Spironolactone - competes with aldosterone for regulatory site

Triamterene - decreases activity of pump directly
•    Either mechanism decreases potassium wasting
•    Either mechanism produces poor diuresis (when used alone)
o    relatively unimportant Na recovery site

Diurectic activity increased if:

•    sodium load (body) is high 
•    aldosterone concentrations are high 
•    sodium load (tubule) is high - secondary to diuresis

Other electrolytes unaffected

Toxicity

•    spironolactone may produce adrenal and sex hormone effects with LONG-TERM use
•    Both drugs may produce electrolyte imbalance
 

PHARMACOLOGY OF LOCAL ANESTHETICS

 Characteristics

1. Block axon conduction (nerve impulse) when applied locally in appropriate concentrations.

2. Local anesthetic action must be completely reversible; however, the duration of the anesthetic block should be of sufficient length to allow completion of the planned treatment.

3. Produce minimal local toxic effects such as nerve and muscle damage as well as minimal systemic toxic effects of organ systems such as the cardiovascular and central nervous system.

Neurophysiology

Nerve fibers exhibit wide range of sensitivity to nerve blockade-in order of increasing resistance to block are the sensations of pain, cold, warmth, touch, pressure, proprioception and motor function

Nerve Fibers:

Myelinated = faster conducting

Unmyelinated = slower conducting

- Small non-myelinated fibers (C- pain fibers) and smaller myelinated pre-ganglionic B fibers are more readily blocked than are larger myelinated fibers responsible for muscle activity and touch [A-alpha and A-beta].

- Clinically, a person would notice complete lack of sensation to a pinprick, while at the same time still be able to move their fingers.

Piroxicam:

Half‐life of 45 hrs. Once‐daily dosing. Delay onset of  action.

High doses inhibits PMN migration, decrease oxygen  radical production, inhibits lymphocyte function. 

used to relieve the symptoms of  arthritis, primary dysmenorrhoea, pyrexia; and as an analgesic,non-selective  cyclooxygenase (COX) inhibitor

The risk of adverse side efects is nearly ten times higher than with other NSAIDs. Peptic ulcer (9.5 higher)