Captopril Sublingual: Mechanism of Action, Indications, Dosage, Precautions, Side Effects, Contraindications and Interactions

It is a hypotensive drug used to treat a hypertensive emergency and is easy to apply, fast, effective and safe.

The treatment of sublingual captopril has been influential in reducing the systodiastolic figures and stabilizing the patient.

Chemical formula


1 – [(2S) -3-mercapto-2-metilpropionil] -L- prolina

Mechanism of action

Captopril inhibits the enzyme that converts angiotensin, which transforms angiotensin I into angiotensin II, a potent endogenous vasoconstrictor substance, resulting in a decrease in blood pressure through a double mechanism.

When arteriovenous vasodilatation occurs, it reduces the peripheral resistance and achieves the reabsorption of sodium and water, with the consequent decrease in blood volume when aldosterone production decreases.

In the case of hypertensive crisis, a unique form of treatment is using sublingual captopril; this means the drug dissolves in the saliva and reaches the circulatory system through the network of venous and lymphatic vessels.

As well as the conjunctive tissue present in the sublingual mucosa, achieving a high speed of absorption.



In a situation where it produces a considerable elevation of blood pressure which must be controlled quickly to prevent damage to the target organs (heart, kidney, retina, brain, and arteries), it is necessary to apply intrahospital treatment with antihypertensive medications.

In these cases, it is common to administer treatments sublingually, to achieve rapid absorption.

Captopril sublingual is indicated for the control of crisis in hypertension in situations of hypertensive emergencies.


The recommended dose for a hypertensive emergency is 25 mg with repetitions every 30 minutes as required, monitoring blood pressure.

With a maximum dose of 100 mg.

This route for medication administration must be used under medical supervision.

The first dose of 25 mg of sublingual captopril guarantees a 25% reduction in blood pressure. The additional intake of 25 mg of captopril ensures optimal blood pressure control; only in extreme cases is it necessary to apply the third dose.


Captopril use can cause facial, lingual, and laryngeal angioedema, which could endanger respiratory capacity. If this happens, the measures to prevent suffocation must be put into practice.

Particular emphasis must be placed on the formulation of the correct dose and the administration of other antihypertensive drugs to avoid hypotensive crises.

It is convenient to carry out constant monitoring of blood pressure levels.

Particular attention should be paid to specific categories of patients at risk, such as immunosuppressed patients or patients with functional renal-type disabilities, among others.

Side effects

Side effects of sublingual captopril are pretty frequent. However, they are not clinically relevant and may occur as episodes of itchy rash, fever, dry cough, photosensitivity, headache, chest pain, dizziness, redness or paleness, and metallic taste.


Sublingual captopril is not recommended in case of hypersensitivity to any of its components, with aortic stenosis and severe kidney function impairment. It is also contraindicated in pregnancy and lactation.

Drug Interactions

Captopril can develop interactions with the following medications:

  • Potassium supplements or diuretics cause an increase in plasma levels of this element.
  • Hypoglycaemic drugs, an increase in the glucose-lowering effect.
  • Corticosteroids with an increase in water retention.
  • Negatively charged membranes, such as hemodialysis, with an increase in anaphylactic episodes.
  • Lithium salts result in accumulation and increase cytotoxic effects.

Captopril sublingual vs embarazo

The benefits of sublingual captopril in the management of hypertensive crises present an alternative for the use of sublingual captopril as an alternative to the medications already known for managing blood pressure in patients with severe preeclampsia or eclampsia.

Small doses have been proposed, and studies have been conducted where satisfactory answers have been obtained, without evidence of complications for the mother, the neonate, or the fetus attributed to the medication.

This absence of complications has been confirmed with the strict measurement of creatinine and urinary volumes during the first 24 hours in the case of the neonate that is attributed to the medication, for which treatment has been recommended.