Histamine And Antihistaminic Agent - Omeprazole

Omeprazole :-

INTRODUCTION:-

1. Omeprazole , sold under the brand name Prilosec & Losec.
2. Originally approved by the FDA in 1989 , Omeprazole is a proton – pump inhibitor. Used to tread Ellison gastric acid related disorders.
3.  It is used in the treatment of gastroesophageal reflux disease , peptic ulcer disease & Zollinger –syndrome.
4. It is also prevent upper gastrointestinal bleeding in people who are at high risk. It is taken by mouth or injected into a vein.
5. When given in a sufficient does (20mg per day) , the acid production can be diminished by more than 95%.
6. Omeprazole is generally effective as well as tolerates tolerated , promoting its popular use in children & adults.

STRUCTURE OF OMEPRAZOLE:-

MECHANISM OF ACTION:-

1. Omeprazole is a selective & irreversible proton pump inhibitor.
2. Hydrochloric acid (HCL) secretion into the gastric lumen is a  process regulated  mainly by the H(+)/K(+)-ATPase of the proton pump , expressed in highquantities by the parietal cells of the stomach.
3. ATPase is an enzyme on the parietal cells membrane that facilitates hydrogen  & Potassium exchange through the cell, which normally results in the extrusions of Potassium & formation of HCL ( gastric acid).

Metabolism:-

1. Omeprazole is heavily metabolized in the liver by the cytochrome p450 ( cyp)  enzyme system. 
2. The main part of its metabolism depends on the polymorphically expressed  CYP2C19, which is responsible for the formation of hydroxyomeprazole,the major metabolite found in plasma.
3. The remaining part depends on CYP3A4, responsible for the formation of Omeprazole sulphone.

PHARMACOKINETICS :-

1. The absorption Omeprazole takes place in the small intestine & it is usually completed within 3-6 hours. 
2. Systemic bioavailability after repeated does is 60%. Plasma half-life is 0.5-1.0 hour.
3. Omeprazole as well as other PPIS, are only effective on a  H+/k+-ATPase pumps.
4. These pump stimulated in the presence of food to aid In  Digestion.  For this reason, patients should be advised to take
5.  Omeprazole with a  glass of water on an empty stomach.

ADVERSE EFFECTS:-

1. Central nervous system :  Headache ( 7%) , dizziness (2%).
2. Respiratory : upper respiratory tract injection (2%), Cough (1%).
3.  Gastrointestinal :  Abdominal pain (5%), diarrhea (4%),
4.  Nausea(4%),  Vomiting (3%), Constipation (2%).
5. Neuromuscular & skeletal : Back pain(1%), weakness (1%).
6.  Dermatological : Rash (2%).
7. Osteoporosis : related fracture.
8. Hypomagnesaemia.
9.  PPI are extremely safe however diarrhea, headache,& abdominal
10. Pain is reported ( 1-5%).

 SIDE EFFECTS:-

More common side effects :-

1. Headache.
2. Stomach Pain.
3.  Nausea.
4. Diarrhea
5. Vomiting.
6. Children’s side effects can include:  Fever

 Serious side effects:-

1. Abnormal or fast heart rate 
2. Jitteriness 
3.  Muscle weakness
4. Dizzinesmethotrs
5. Tremors

 

USES:-

1. Gastroesophageal reflux disease (GERD).
2. Gastric (stomach) ulcers or duodenal ulcers.
3. Zollinger – Ellison syndrome
4. Stomach injection caused by Helicobacter pylori bacteria.

PRECAUTIONS:-

1.  Pregnancy cat C .
2.  Do not crush , chew or break.

Warnings:-

1.  Allergy alert :   Do not use if you are allergic to Omeprazole.
2. Do not use if you have trouble or pain swallowing food, vomiting  with blood, or bloody or black stools.
3. These may be signs of a serious condition. See your doctor.