AGENTS AFFECTING GIT WATER FLUX AND MOTILITY

Introduction

GI motility refers to wall movement in the digestive tract. 

The enteric nervous system is the most important regulator of physiological gut function including contraction, absorption and secretion.

  Other regulatory systems in the gut include the CNS and humoral pathways.

Role of the ENS in GI motility

The  ENS is an autonomous collection of nerves within the wall of the GI tract.

It  consists of:

The  myenteric (Auerbach’s) plexus which is found between the circular and longitudinal muscle layers

The  submucosal (Meissner’s) plexus, found below the epithelium.

Auerbach’s plexus is responsible for motor control, while the Meissner’s plexus regulates secretion, fluid transport, and vascular flow.

Overview of  motility disorders of the bowel

Decreased GI motility can affect one or more parts of the GIT

TREATMENT OF PEPTIC ULCERS AND GASTRO-OESOPHAGEAL REFLUX DISEASE

Peptic ulcer disease  (PUD):

a condition in which there is a discontinuity in the entire thickness of the gastric or duodenal mucosa that persists as a result of acid and pepsin in the gastric juice.

 In the stomach, mucus and bicarbonate, stimulated by the local generation of prostaglandins, protect the gastric mucosa.

If these defences are disrupted, a gastric or duodenal ulcer may form.

Infection with Helicobacter pylori and use of NSAIDs also play a key role in the pathogenesis of acid-peptic diseases and these factors should be considered in treatment and  prevention  of PUD

Causes of PUD

NAUSEA AND VOMITING

Introduction

Nausea and vomiting are protective mechanisms designed to :

Rid  the body of  toxic substances

Prevent  their further ingestion.

Phases of vomiting

Vomiting may be divided into three phases:

Nausea ( preejection phase)

TOPICAL ANTI-INFECTIVE AGENTS

ANTIBACTERIAL AGENTS

Introduction

Topical antibacterial agents may be useful in:

Preventing   infections in clean wounds,

In  the early treatment of infected dermatoses and wounds,

In  reducing colonization of the nares by staphylococci,

In  axillary deodorization,

In the management of acne vulgaris.

The efficacy of antibiotics in these topical applications is not uniform.

Antibiotic-corticosteroid combinations

Topical  anti-infectives may  contain corticosteroids in addition to antibiotics.

ANTIHISTAMINES

Introduction

Histamine is a potent vasodilator, bronchial smooth muscle constrictor, and stimulant of nociceptive itch nerves. In addition to histamine, multiple chemical itch mediators can act as pruritogens on C-fibers, including neuropeptides, prostaglandins, serotonin, acetylcholine, and bradykinin.

Histamine receptors

Human skin mast cells express H1, H2, and H4 receptors but not H3 receptors.

H1 and H2 receptors are involved in wheal formation and erythema,

Only H1 receptor agonists cause pruritus

ACNE PREPARATIONS

Retinoic acid derivatives

Retinoic acid, also known as tretinoin or all-trans-retinoic acid, is the acid form of vitamin A.

It is an effective topical treatment for acne vulgaris.

Several analogs of vitamin A, e.g. 13-cis-retinoic acid (isotretinoin), are effective in various dermatologic diseases when given orally.

Retinoic acid derivatives

PHOTOCHEMOTHERAPY

Introduction

Phototherapy and photochemotherapy are treatment methods in which ultraviolet or visible radiation is used to induce a therapeutic response either alone or in the presence of a photosensitizing drug respectively.

Phototherapy using UVB or high-dose UVA-I is efficacious in selected dermatological diseases.

To be effective, the incident radiation must be absorbed by a target or chromophore in the skin.

 In phototherapy the chromophore is