Instillido (Lidocaine Hydrochloride)

Instillido, a urethral local anesthetic, is used to achieve temporary loss of sensation in the urethral tract.

• Urethral anesthesia: provides localized numbness for cystoscopic examinations.
• Urethral catheterization: reduces pain and discomfort during catheter insertion.
• Minor urethral procedures: facilitates painless dilation or biopsy.

• Lidocaine Hydrochloride blocks voltage‑gated sodium channels on neuronal membranes, preventing the initiation and propagation of action potentials. By stabilizing the neuronal membrane, it inhibits nerve impulse conduction in the targeted urethral tissue, resulting in rapid onset of reversible local anesthesia without affecting surrounding structures.

Lidocaine Hydrochloride may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Burning or stinging sensation at the application site.
• Transient numbness extending beyond the intended area.
• Mild urinary urgency or frequency.
• Mild headache or dizziness.

Serious or Rare Side Effects

• Allergic reactions such as rash, angioedema, or anaphylaxis.
• Severe hypotension or cardiovascular collapse.
• Cardiac arrhythmias, including ventricular tachycardia.
• Methemoglobinemia, seizures, or respiratory depression.

When using Instillido, several safety measures should be observed to minimize risk.

• Allergy assessment: verify no known hypersensitivity to amide‑type local anesthetics.
• Cardiac monitoring: avoid use in patients with significant conduction abnormalities.
• Dose limitation: use only the amount required for the procedure.
• Concomitant medications: review for agents that may potentiate systemic lidocaine levels.
• Pregnancy and lactation: consider risk‑benefit; use only if clearly needed.
• Store at room temperature: keep in original container, protect from moisture and light.

Lidocaine may interact with other drugs, altering its systemic exposure or cardiac effects.

Major Interactions (Avoid)

• Class I antiarrhythmics (e.g., quinidine, procainamide) that increase the risk of cardiotoxicity.
• Other amide‑type local anesthetics, which can lead to cumulative toxicity.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) that raise plasma lidocaine levels.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine) that may reduce efficacy.
• Cimetidine or other H2‑blockers that modestly increase lidocaine concentrations.
• Diuretics that may affect electrolyte balance and cardiac stability.