Mechanism of Action and Secretion Physiology
Normally, hydrogen ion (H⁺) secretion is performed by gastric parietal cells. This process is tightly regulated by the central nervous system and humoral factors through three main stimulation pathways:
- Neuronal: acetylcholine stimulates M₃ muscarinic receptors (signals transmitted via the vagus nerve).
- Paracrine: histamine acts locally on H₂ histamine receptors. Histamine release is mediated by enterochromaffin-like cells when the cholinergic system stimulates their M₁ receptors.
- Humoral: gastrin activates CCK₂ receptors.
The intracellular signaling cascade (such as upon H₂ receptor activation) involves receptor coupling to Gs proteins, adenylate cyclase activation, cAMP accumulation, and the activation of cAMP-dependent protein kinases. The final target is the H⁺, K⁺-ATPase enzyme («proton pump»), which transports hydrogen ions from the cell into the gastric lumen in exchange for potassium ions.
Administration of Acidum hydrochloricum dilutum does not affect these receptor mechanisms. The drug works via replacement therapy — it physically replenishes the deficiency of endogenous hydrochloric acid in the gastric lumen.
Pharmacological Effects
The preparation recreates the necessary acidic environment in the stomach (gaster). This is critical for normal digestion: the acidic environment ensures protein denaturation and digestion, and is required for the activity of proteolytic enzymes (pepsin).
From a pharmacokinetic perspective, hydrochloric acid acts as a potent chemical barrier. It destroys acid-labile substances (e.g., benzylpenicillin) and is one of the factors reducing the bioavailability of numerous orally administered drugs before they reach the portal vein and liver. The stomach is only the initial transit phase. The primary site of drug absorption into the venous blood is the small intestine (intestinum tenue), where chyme passes after acid processing.
Indications for Use
The primary indication is digestive gland hypofunction accompanied by a decrease in or complete absence of endogenous hydrochloric acid production.
The drug is used strictly as part of replacement therapy. It is important to remember that such treatment does not address the underlying etiology of the disease or affect its pathogenesis. The goal of therapy is to mitigate the manifestations of a vital substance deficiency. The nature of application in such cases is typically long-term (course-based or lifelong).
Interactions with Other Substances and the GI Environment
- Antacids: react directly with hydrochloric acid via an extracellular mechanism, neutralizing it. This impairs protein denaturation and digestion.
- Food Effects: food delays gastric emptying, which postpones the transit of medications into the intestine and slows their absorption rate. An exception is lipophilic substances: fatty food stimulates bile secretion, enhancing their emulsification and absorption.
- Drug Protection from Acid: to protect acid-labile medications from destruction by hydrochloric acid, enteric-coated dosage forms (tablets or capsules with acid-resistant coatings) are used. They pass through the stomach unchanged and disintegrate only in the small intestine. Alternatively, sublingual or buccal administration allows lipophilic non-polar substances to be absorbed via passive diffusion in the oral cavity, bypassing the harsh gastric environment and first-pass hepatic metabolism.
Administration Considerations and Risks
The medication is available in 15, 30, and 100 mL bottles. It is administered orally (per os). The recommended dosage is 10–15 drops, which must be diluted in 1/2 cup of water. It is taken 3–4 times daily.
Clinical Mucosal Protection Note: Excess gastric hydrochloric acid is extremely dangerous when defensive mucosal factors are diminished. For example, during the administration of ulcerogenic drugs (NSAIDs), non-reactive inhibition of the COX-1 enzyme occurs. This reduces the synthesis of prostaglandins (E2 and I2) responsible for protective mucus and bicarbonate production. Under these conditions, acid damages the gastric wall (NSAID-induced gastropathy). Using milk to wash down medications for acid protection is ineffective: milk provides only a temporary buffering effect, while calcium ions can secondarily stimulate hydrochloric acid secretion. Proton pump inhibitors or prostaglandin analogues are required for gastroprotection.