Guanfacine (medication): what it is, and characteristics of this drug

Guanfacine is an antihypertensive drug used for the treatment of ADHD. (Attention Deficit Hyperactivity Disorder) and for cases of high blood pressure. It is a selective adrenergic receptor agonist.

In this article we will know the characteristics of this drug (format, administration, mechanism of action...), its indications, adverse effects, studies and precautions to be taken into account for its utilization.

• Related article: "Types of ADHD (characteristics, causes and symptoms)"

Guanfacine: general characteristics

Guanfacine is an antihypertensive drug, with the trade name "Intuniv". On a chemical level, it derives from phenylacetylguanidine. Its mechanism of action is based on selective adrenergic (adrenaline) agonism for alpha 2A (α2A) receptors.

The effects of guanfacine are to lower blood pressure. As it does? Activating receptors found in the brain stem and inhibiting the activity of the sympathetic system (this system is part of the Autonomic Nervous System (ANS) and is related to the activation and preparation of the organism for the struggle).

All this translates into a reduction in nerve impulses from the heart and blood vessels; that is, what guanfacine does is relax the latter, also reducing blood pressure and improving blood flow.

• You may be interested in: "Types of psychoactive drugs: uses and side effects"

Mechanism of action

Thus, the mechanism of action of guanfacine consists, as we said, in producing a selective agonist effect at alpha 2A adrenergic receptors.

In the case of the administration of guanfacine for Attention Deficit Disorder with hyperactivity (ADHD), which we will see later, the exact mechanism that produces the effects is unknown therapeutic; however, preclinical studies suggest actions in the prefrontal cortex and in the basal ganglia. These actions are related to the intervention on norepinephrine in the aforementioned receptors.

Administration

Guanfacine is administered orally (in tablet form). Your recommended starting dose is usually once a day; ideally in the morning or at night. Guanfacine, like many other drugs, can be taken with or without food. On the other hand, something to note is that it is not recommended to take it with foods rich in fat, or with grapefruit juice.

Its tablets are prolonged release, and correspond to the following quantities: 1 mg, 2 mg, 3 mg or 4 mg.

Indications

The indications for guanfacine include cases of arterial hypertension and Attention Deficit Hyperactivity Disorder (ADHD), and it has been authorized for both types of pathologies. In the case of arterial hypertension, guanfacine is generally used in combination with other medications to reduce this tension.

On the other hand, in the case of ADHD, a series of specifications are established for the administration of guanfacine: It will be used only in children and adolescents between 17 and 17 years of age., and in cases where stimulants have been used previously and have not provided good results, not being tolerated or proving ineffective.

In addition, in this second case, it should be used as part of a comprehensive ADHD treatment that also includes psychological treatment and educational and social measures.

Considerations and precautions

The only contraindication that guanfacine presents is to manifest a hypersensitivity to it. Regarding precautions, in cases of liver failure it will sometimes be necessary to reduce your dose.

On the other hand, in relation to pregnancy and lactationIt is not recommended to take guanfacine while pregnant, nor if you are a woman, are of childbearing age and do not use any contraceptive method.

In the lactating period it is not known exactly whether guanfacine (or its metabolites) are excreted in breast milk, but animal studies suggest that they are. Thus, lactating women should evaluate the risks and benefits of their case, and assess the best option (either interrupting breastfeeding or interrupting treatment with guanfacine).

Another aspect to take into account is that we should not suddenly stop taking guanfacine, as this could cause an increase in blood pressure. Finally, it should avoid taking guanfacine when you have to drive, or when you have to do a task that requires a high level of alertness.

Use in ADHD

The pharmacological treatment typically used for Attention Deficit Hyperactivity Disorder (ADHD) are stimulants. However, guanfacine has also been used for these cases, although it is not a stimulant. The exact mechanism of action of guanfacine in ADHD is unknown, but it is known that interacts with brain areas involved in attention and impulses.

Specifically, delayed-release (or prolonged-release) guanfacine has been used for this, proving to be an effective treatment option with good tolerance for patients. In fact, it's FDA-approved for children with ADHD ages 6 and up. The FDA is the United States government agency responsible for regulating medicines and other types of products (cosmetics, medical devices, biological products...).

1. Adverse effects in ADHD

The adverse effects that have been found with the administration of guanfacine for ADHD have been, from more to less frequent: drowsiness, tiredness and/or fatigue (in 40% of cases), headache (25%) and abdominal pain (less frequent, only in 10% of cases).

On the other hand, the symptom of drowsiness improves when delayed-release guanfacine is administered together with some type of stimulant, such as methylphenidate (brand names: rubifen, medikinet, or concerta) or lisdexamfetamine (elvanse). Thus, guanfacine associated with stimulants provides a better therapeutic response than when administered alone, since it alleviates its adverse effects.

2. Studies

Although guanfacine has been shown to be effective in some cases of ADHD, there is not enough research to know the effects of long-term (used for several years) extended-release guanfacine use in children aged 6 and over years. That is why we must be cautious.

Side effects

Some of the adverse reactions produced by guanfacine are: sedation, dizziness, hypotension, nightmares, constipation, nausea, vomiting, diarrhea, emotional lability, anxiety, depression, reduced appetite or weight gain and abdominal pain.

Furthermore, it is known that drinking alcohol while taking guanfacine may lead to an increase in some of these adverse reactions.

In relation to the adverse effects of guanfacine on the heart, we find: low blood pressure, slow heart rate and other changes in heart rhythm. These effects are serious enough to require medical supervision (and monitoring).