Famotidine

BRAND NAMES:

Pepcid- It consists of the main active ingredient as Famotidine 20mg and 40mg tablets. Available as Pepcid famotidine 20mg tablets 

Zantac- Famotidine is the major active ingredient in the Zantac for duodenal ulcer taken 150mg twice daily. 

MECHANISM OF ACTION:

Enterochromaffin-like cells are neuroendocrine cells that live near parietal cells and regulate histamine release at the basic level. Acetylcholine and the peptide hormone gastrin stimulate histamine release. The proton pump increases acid secretion by releasing more protons into the stomach. Ulcers, for example, are related with acid hypersecretion. Famotidine inhibits histamine activity by binding to H2 receptors.

PHARMACOKINETICS:

Absorption: The bioavailability of oral famotidine ranges from 40% to 45 %. Oral administration, famotidine exhibits an onset of action within 1 hour and reaches its peak effect within 1 to 3 hours. The intravenous administration of the drug results in a peak effect within approximately 30 minutes. The anti-secretory effect of famotidine typically persists for around 10 to 12 hours.

Distribution: Famotidine exhibits a plasma protein binding of 15% to 20%, accompanied by a relatively small volume of distribution between 1.0 and 1.3L/kg.

Metabolism: Famotidine has limited first-pass metabolism and is largely metabolized by the cytochrome P450 system, notably CYP1A2. Hepatic metabolism eliminates approximately 25-30% of the medication. The only metabolite known in humans is S-oxide.

Excretion: Famotidine elimination half-life ranges from 2.5 to 3.5 hours. Around 65% to 70% of famotidine is excreted unchanged in the urine.

PHARMACODYNAMICS:

Famotidine suppresses both baseline and nocturnal stomach acid production, as well as acid secretion induced by meals, caffeine, insulin, and pentagastrin. Famotidine's therapeutic activity is dosage dependent, with the highest dose providing the longest duration of action and the strongest inhibitory effect on gastric acid output. Famotidine reduces stomach acid production, acid concentration, and pepsin content, as well as the volume of gastric secretions.

DOSE AND ADMINISTRATION:

Famotidine comes in the form of pills and suspension. 

Tablets -10mg, 20mg, and 40mg 

Tablets chewable -10mg and 20mg. 

Oral suspension: -40 mg/5 mL

Famotidine is available in two forms: tablets and oral suspension. It is typically given once daily at bedtime, or twice to four times each day. Famotidine is available over the counter form of tablets, chewable tablets, and capsules for oral administration. It is often taken by mouth. It is often taken once or twice a day. To avoid symptoms, take 15 to 60 minutes before eating or drinking anything that may induce heartburn.

CONTRAINDICATIONS:

Famotidine is contraindicated for patients with hypersensitivity to famotidine or any of its formulation components. Due to observed cross-sensitivity among H2RAS, famotidine should not be prescribed to patients with a history of hypersensitivity to cimetidine. OTC tablets should not be used by patients experiencing difficulties or pain while swallowing food, exhibiting vomiting with blood or noticing the presence of bloody or black stools. The OTC famotidine tablets should also not be administered to patients who are allergic to or are currently taking other acid reducers, as well as those with renal impairment.

DRUG INTERACTIONS:

Other may interact with famotidine include

• Anticoagulants – warfarin, Aspirin

• Anti-fungal drugs- fluconazole, itraconazole, ketoconazole, or voriconazole

• Tumor drugs- Bosutinib, dabrafenib, dasatinib, erlotinib, neratanib or         Pazopanib

• Epilepsy medications- carbamazepine, fosphenytoin, phenobarbital or phenytoin

• HIV medications- atazanavir and ritonavir.

• Iron supplements- ferrous fumarate, ferrous gluconate, or ferrous sulfate

• Loperamide

• Metformin

• Multivitamins

• warfarin

SIDE EFFECTS:

Famotidine oral pills may produce mild or severe adverse effects. 

• Problems with heart rate and rhythm include dizziness, fainting, shortness of breath, and irregular heartbeat. 

• Severe muscle difficulties, including pain, weakness, and fever. 

• Neurological disorders include agitation, anxiety, sadness, difficulty sleeping, and seizures. 

• Liver disorders include unusual weakness, decreased appetite, stomach pain, and changes in urine color. 

• Skin issues: blisters, redness, and mouth sores.

• Overdose

• When we consume harmful amounts of drugs in the body. The following signs indicate a drug overdose: 

• Agitation 

• Confusion 

• Seizures 

• Severe muscular ache.

TOXICITY:

Any unabsorbed medicine should be removed from the gastrointestinal tract and the patient monitored accordingly. Hemodialysis is an effective method for eliminating the medication from the systemic circulation, however clinical experience with hemodialysis in reaction to famotidine overdose is limited. Because famotidine is mostly removed through the kidneys, the risk of toxicity may be increased in people with weakened renal functions. Patients with moderate-to-severe renal impairment require dose modifications.

STORAGE:

Store the oral pills at 77°F (25°C). They can be stored for a short period between 59°F and 86°F (15°C to 30°C).