Instillido (Lidocaine Hydrochloride)

Instillido, containing lidocaine hydrochloride, is employed in urethral procedures to provide localized anesthesia and improve patient comfort.

• Urethral catheterization: reduces pain and spasm during insertion of urinary catheters.
• Diagnostic cystoscopy: numbs the urethral tract to facilitate tolerable endoscopic examination.
• Minor urethral surgery: provides intra‑procedural anesthesia for interventions such as urethrotomy.
• Urethral stent placement: eases discomfort associated with stent insertion.
• Urethral dilation: diminishes pain during gradual widening of the urethral lumen.

• Lidocaine hydrochloride exerts its anesthetic effect by reversibly binding to the intracellular portion of voltage‑gated sodium channels on neuronal membranes. This blockade prevents the rapid influx of sodium ions required for depolarization, thereby inhibiting the generation and propagation of nerve impulses. The result is a rapid onset of localized loss of sensation without affecting surrounding muscle function. The effect is concentration‑dependent and typically lasts for the duration of the procedure.

Lidocaine administered urethrally may be associated with local and systemic adverse reactions, most of which are mild and transient.

Common Side Effects

• Burning sensation at the application site.
• Transient urinary urgency or frequency.
• Mild local irritation or erythema.
• Temporary numbness lasting minutes to hours.

Serious or Rare Side Effects

• Systemic toxicity presenting as dizziness, tinnitus, or seizures.
• Severe allergic reaction with rash, swelling, or anaphylaxis.
• Cardiac arrhythmias such as bradycardia or ventricular ectopy.
• Methemoglobinemia causing cyanosis and shortness of breath.

When using Instillido, clinicians should observe specific safety measures to minimize adverse events and ensure optimal efficacy.

• Allergy assessment: verify no known hypersensitivity to lidocaine or other amide‑type anesthetics.
• Urethral condition: avoid use in active infection, severe inflammation, or traumatic injury.
• Dosage control: adhere strictly to the prescribed volume to prevent systemic absorption.
• Concurrent anesthetics: do not combine with other local anesthetics without specialist guidance.
• Pregnancy and lactation: use only when the potential benefit justifies the possible risk to the fetus or infant.
• Store at room temperature: keep in the original container, protect from light and moisture.

Lidocaine can interact with other medicines, altering its plasma concentration or enhancing cardiovascular effects; awareness of these interactions helps prevent complications.

Major Interactions (Avoid)

• Class I antiarrhythmic agents (e.g., quinidine, procainamide): may increase lidocaine plasma levels and toxicity.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): can reduce metabolism and elevate systemic exposure.

Moderate Interactions (Monitor Closely)

• Beta‑blockers and calcium‑channel blockers: may potentiate lidocaine’s negative inotropic and conduction effects.
• Concurrent use of other local anesthetics: raises risk of cumulative neuro‑ and cardiotoxicity.
• Epinephrine‑containing solutions: can modify absorption rate and cardiovascular response.