Ipratropium

BRAND NAMES:

Combivent: It contains the active ingredients of Ipratropium bromide and albuterol sulfate. It is available as an inhalation aerosol used to make breathing easy.

Ipravent: It contains the active ingredient of Ipratropium bromide. It is available in the form of a respiratory solution.

Atrovent: It contains the active ingredient of ipratropium bromide. It is available in the form of aerosol.

MECHANISM OF ACTION:

The administration of ipratropium inhibits the metabolism of acetylcholine in smooth muscle, inhibiting airway contraction and inducing relaxation. At the molecular level, the width of the airways is regulated by the release of acetylcholine into muscle cells, which causes them to contract and narrow the airway. It works as an antagonist for the muscarinic acetylcholine receptor. This action inhibits the parasympathetic nervous system in the airways, preventing them from functioning properly. The parasympathetic system's job in the airway is to promote bronchial secretion and construction; hence, inhibiting this activity might cause bronchodilation and less secretion. 

PHARMACOKINETICS:

Absorption: After delivery, ipratropium is deposited in the gastrointestinal system, with a lesser percentage reaching the lung, which is its designated site of action. Because it is a quaternary amine, it has little systemic absorption. The time to enhance pulmonary function is around 15 minutes, the peak plasma concentration is reached in 1 to 2 hours, and the effect lasts for 2 to 4 hours. Ipratropium nasal formulation has a systemic absorption of less than 20% and a beginning of action of about 15 minutes.

Distribution: Ipratropium has a volume of distribution of 4.6 L/kg and is thus known to be widely dispersed in tissues.

Metabolism: The absorbed fraction is largely converted by ester hydrolysis into inactive metabolites such as tropic acid and tropane. Ipratropium is metabolized in the gastrointestinal system by cytochrome P-450 enzymes. Approximately 90% of the orally taken dosage is excreted unaltered.

Excretion: Ipratropium has an elimination half-life of about 2 hours. Approximately 50% of the dosage is eliminated unaltered in urine.

PHARMACODYNAMICS:

Ipratropium is a short-acting drug that inhibits the parasympathetic nervous system in the airway, resulting in bronchodilation. The impact of this drug begins after 1-2 hours and is known to last only 4 to 6 hours. Ipratropium has the action of relaxing the bronchial airways, which reverses the constriction that causes wheezy breathing, chest tightness, coughing, and irregular gas exchange.

ADMINISTRATION:

Ipratropium is available in two forms: a solution for oral inhalation with a nebulizer and an aerosol for oral inhalation with an inhaler. The nebulizer solution is often used three or four times a day, once every six to eight hours. The aerosol is typically used four times each day. Don't use more or less of it, or use it more frequently than suggested by your physician.

DOSAGE AND STRENGTH:

This dosage is available in both metered-dose inhalers and nebulized solutions. 

Inhalation aerosol: 2 inhalations orally four times each day, or as needed, for a total of 12 inhalations in 24 hours.

Nebulizer inhalation solutions: 500 mcg three or four times per day by oral nebulization, with dosages lasting 6 to 8 hours.

Usual pediatric dose for chronic obstructive pulmonary diseases:

Nebulizer inhalation solution: 

Solution for nebulizer inhalation for children under 12 years old. The safety of taking 500 mcg three or four times a day via oral nebulization with doses 6 to 8 hours apart is unknown for those aged 12 and up.

DRUG INTERACTIONS:

Ipratropium may interact with medications from the following classes that have anticholinergic activity.

• Revefenacin and Aclidinium
• Anti-depressants: Amitriptyline and Paroxetine
• Anti-histamines: diphenhydramine, hydroxyzine, and chlorpheniramine
• Agents for overactive bladder: Darifenacin, Oxybutynin, and Solifenacin
• Anti-Parkinson agents: Benztropine and Trihexyphenidyl
• Antipsychotics: olanzapine, quetiapine, and haloperidol
• Cardiovascular agents: disopyramide
• Atropine and Hyoscyamine
• Muscle relaxants: cyclobenzapine

CONTRAINDICATIONS:

Contraindications to ipratropium inhaler use include patients with hypersensitivity to ipratropium bromide or atropine due to the structural similarity between ipratropium bromide and atropine.

SIDE EFFECTS:

Ipratropium may cause side effects.

• Dizziness
• Nausea
• Heartburn
• Constipation
• Dry mouth
• Difficulty urinating
• Pain when urinating
• Back pain

Some side effects can be serious

• Rash
• Hives
• Itching
• Swelling of the eyes, face, lips, tongue, throat, hands, feet, ankles, or lower legs
• Chest pain

OVERDOSE:

Overdose symptoms can include

• Chest pain
• Fast or pounding heartbeat
• Tremors
• Dry mouth
• Extreme thirst
• Muscle weakness
• Severe headache

TOXICITY:

A high dose of ipratropium can cause toxicity similar to anticholinergic toxicity. Reports have indicated that ipratropium exacerbates ischemic injuries in nonclinical settings.

STORAGE:

Inhaled ipratropium vials should be kept at room temperature. The vials should be maintained in the foil pouches until used and kept away from light.