Instillagel (Chlorhexidine Gluconate, Methyl Parahydroxybenzoate, Propyl Parahydroxybenzoate, Lidocaine Hydrochlo)

Instillagel is used in the urological field to provide antisepsis and local anaesthesia for procedures involving the urethra.

• Urethral catheterisation: provides antiseptic cleansing and local anaesthesia to facilitate catheter insertion.
• Prevention of catheter‑associated urinary tract infection: reduces bacterial colonisation of the urethra during catheter use.
• Urethral procedures (e.g., cystoscopy): offers temporary numbing and antimicrobial protection during diagnostic or therapeutic interventions.

• Chlorhexidine gluconate disrupts bacterial cell membranes by binding to phospholipids, leading to leakage of intracellular contents and cell death. Lidocaine hydrochloride blocks voltage‑gated sodium channels in peripheral nerves, preventing depolarisation and producing reversible local anaesthesia. The combination delivers rapid antiseptic action together with short‑duration numbness at the site of application.

Instillagel may cause local and systemic adverse reactions.

Common Side Effects

• Mild urethral irritation: transient burning or stinging sensation.
• Localised redness or mild inflammation at the application site.
• Temporary numbness lasting a few minutes after use.
• Minor allergic skin reaction such as itching or rash.

Serious or Rare Side Effects

• Severe allergic reaction (anaphylaxis) requiring immediate medical attention.
• Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Significant urethral ulceration or tissue necrosis.
• Systemic lidocaine toxicity presenting as dizziness, tinnitus, or cardiac arrhythmia.

Before using Instillagel, consider the following safety measures.

• Allergy assessment: verify no known hypersensitivity to chlorhexidine, lidocaine, or the preservatives.
• Pregnancy and lactation: use only if the clinical benefit outweighs potential risk.
• Urethral injury: avoid application in patients with traumatic urethral lesions or recent surgery.
• Concurrent antiseptics: do not use other chlorhexidine‑containing products simultaneously to prevent excess exposure.
• Storage: Store at room temperature below 25°C: keep in the original container, protect from moisture and light.

Instillagel can interact with certain systemic medications.

Major Interactions (Avoid)

• Lidocaine with Class I antiarrhythmic agents (e.g., quinidine): may increase systemic lidocaine levels.
• Chlorhexidine with ototoxic drugs (e.g., aminoglycosides): potential additive toxicity if absorbed.
• Concurrent use of other topical anesthetics: risk of cumulative lidocaine toxicity.

Moderate Interactions (Monitor Closely)

• Systemic analgesics (e.g., opioids): may enhance local anaesthetic effect.
• Renal impairment: monitor for lidocaine accumulation and adjust use accordingly.
• Use with other antiseptics: may increase local irritation or chemical incompatibility.