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Phloroglucinol

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Phloroglucinol

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Medically reviewed

Marina Burgos

Last updated on 10/01/2026

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Phloroglucinol

Property Description
Active ingredient Phloroglucinol (C6H6O3)
Forms Tablets, Injection Solution, Suppositories
Pharmacological Class Musculotropic Antispasmodic Agent
General Purpose Relief of acute spastic pain (colic)
Origin Synthetic Organic Compound

What is Phloroglucinol and What is its Pharmacological Class?

Phloroglucinol is a specialized medication classified as a musculotropic antispasmodic agent, defined by its direct action on smooth muscle tissue. This synthetic phenol derivative is chemically known as 1,3,5-Trihydroxybenzene. Pharmacologically, it is designated under the Anatomical Therapeutic Chemical (ATC) Classification System as A03AX12, a code identifying it as a drug for functional gastrointestinal disorders. Unlike general pain relievers, Phloroglucinol's primary therapeutic purpose is to achieve symptomatic relief by directly resolving the underlying physical cause of the discomfort, specifically the spasm itself, which is a key differentiator from analgesic treatments.

Composition, Forms, and Origin of Phloroglucinol

The medication is predominantly a single-active-ingredient product, containing only Phloroglucinol as the functional compound. As a synthetic organic compound, it is manufactured rather than directly extracted from natural sources. This active ingredient is prepared into multiple dosage forms to accommodate various needs and administration requirements. These forms include tablets for oral use, a solution for injection for rapid parenteral delivery in clinical settings, and suppositories for rectal administration. In certain preparations, the compound is combined with its derivative, trimethylphloroglucinol, a formulation intended to offer a potentially synergistic effect on smooth muscle relaxation.

How Does Phloroglucinol Generally Help with Spasms?

Phloroglucinol generally helps with spastic pain by directly inducing smooth muscle relaxation in the affected internal organs. Its high-level mechanism involves interfering with the cellular processes that govern calcium entry into the muscle cells, thereby preventing the sustained, painful contractions that define a spasm. This focused spasmolytic action ensures that the drug provides targeted relief for severe, acute pain originating from functional spasms in the tracts of the body. A typical use scenario involves providing quick relief for pain associated with renal colic or spasms affecting the biliary or digestive tracts.

What side effects are possible with Phloroglucinol?

Possible Side Effects and Safety Information

The officially documented safety profile for Phloroglucinol centers primarily on hypersensitivity reactions (allergic responses) affecting the skin and other systems. Adverse reactions are classified according to frequency, as noted in regulatory documents.

Documented Adverse Reactions

Classification Adverse Reaction
Rare Urticaria (hives)
Exceptionally Quincke's oedema (angioedema), Anaphylactic shock (including low blood pressure), Generalized acute exanthematous pustulosis (AGEP)
Frequency Not Known Eruption (rash), Pruritus (itching)

The most serious adverse events listed in official labeling are the Exceptionally occurring hypersensitivity reactions, such as Anaphylactic shock and Quincke's oedema.

Safety Constraints and Special Populations

Safety limitations are explicitly defined by contraindications in cases of known hypersensitivity to Phloroglucinol or its excipients. Formulations containing specific excipients are also contraindicated for individuals with certain rare hereditary conditions, such as lactose intolerance or Phenylketonuria (PKU), when aspartame is present.

  • Pregnancy and Breast-feeding: Regulatory information advises that use during pregnancy should only be if necessary due to limited human data. Avoidance is generally advised during breast-feeding due to an absence of conclusive safety data.
  • Drug-Related Safety Note: Official documentation notes that co-administration of Phloroglucinol with morphine or morphine derivatives should be avoided. This is due to the potential for these analgesics to induce or aggravate spasmogenic (spasm-causing) effects, which can compromise the anti-spasmodic treatment.

Overdose and Emergency Response

Overdose and when to seek help

The regulatory guidance for Phloroglucinol overdose focuses primarily on the immediate action required following suspected excessive ingestion. Official documents note that while overdose events have been reported, there are no specific symptoms or characteristic clinical signs that are formally documented as unique manifestations of Phloroglucinol overexposure. The overdose profile is thus defined by the necessary emergency response rather than a distinct set of clinical observations.

When to Seek Immediate Medical Help

The core regulatory requirement is to seek medical attention without delay in any suspected overdose scenario. If a person, or a child, has accidentally swallowed too much of the medicine, regulators mandate that the patient or caregiver must contact the nearest hospital casualty department or tell their doctor immediately.

Immediate consultation is necessary to ensure that timely treatment can be provided. Patients should be prepared to take the product packaging to the medical facility for identification.

Management and Antidote

Management of Phloroglucinol overdose is described as being symptomatic and supportive, as there is no specific antidote known or documented in the official prescribing information to reverse the effects of the drug. Due to the absence of a known reversing agent, hospital monitoring may be required to manage any clinical changes that arise.

Therapeutic Uses of Phloroglucinol

What Phloroglucinol Treats: Main Uses and Benefits

Phloroglucinol is commonly used to provide supportive symptomatic relief across several key areas where smooth muscle spasms (cramps) can be a source of acute discomfort, and provides support that helps ease the overall symptom burden during periods of heightened symptoms. The medication is applied in addressing symptomatic pain linked to organ systems, which may include the digestive tract, the urinary tract, and gynecological discomfort.

Symptom-Focused Relief

This therapy is applied across domains where additional symptomatic support is needed, and is relevant for managing symptoms that may appear suddenly or intensify, such as the acute pain seen in renal colic or biliary spasms. It is relevant for managing symptoms that interfere with daily comfort. Phloroglucinol may assist with maintaining a sense of stability when symptoms are more noticeable, providing support during phases of increased distress. It may also help patients cope more steadily with symptom fluctuations associated with recurrent or episodic manifestations.

Quick Fact: Relief for Spasmodic Pain

Regulatory References

  1. Malta Medicines Authority Package Leaflet

Eligibility and Restrictions for Use

Who can and cannot use Phloroglucinol?

The official regulatory documents define clear population eligibility rules for Phloroglucinol. Use is established for adults and for children over 2 years of age. However, use is formally not established for children under two years, setting a minimum eligibility age.

Contraindicated Populations

Phloroglucinol is contraindicated in several specific populations and conditions:

  • Individuals with a known hypersensitivity to the active substance or any of the product's excipients.
  • Patients with Phenylketonuria (PKU) due to the presence of aspartame in some oral formulations.
  • Patients with rare hereditary metabolic issues, such as galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption, due to the lactose content in tablets.
  • Patients diagnosed with functional ileus or intestinal obstruction.

Use Limitations

Use of this medicine requires careful consideration in specific physiological states:

  • Pregnancy: Use should only be considered if necessary, according to official labeling.
  • Lactation: Use is not recommended while breastfeeding, as insufficient data is available regarding the substance's excretion into breast milk.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The official interaction profile of Phloroglucinol is narrowly defined, primarily focusing on a single, significant interaction based on pharmacological effect, according to regulatory documentation.

Interaction Scope

The main regulatory restriction involves Major Analgesics, specifically Morphine and its Derivatives. This is classified as a pharmacodynamic interaction, meaning the substances directly oppose each other's effects on the body. This combination is listed as a prohibited co-administration because these specific analgesics are known to have a spasmogenic (spasm-causing) effect, which directly counteracts the intended spasmolytic (anti-spasm) action of Phloroglucinol, compromising its function.

Interaction Classifications (High-Level)

The interaction severity is classified by regulatory authorities as a contraindicated combination or one that must be avoided. The constraint is entirely based on the pharmacologic conflict arising from the compounds' opposing effects on smooth muscle tissue.

Resulting Interaction Structure

Official prescribing information does not detail specific restrictions related to changes in the drug's plasma concentration via metabolic pathways, such as the Cytochrome P450 enzyme system, or via drug transporters. Consequently, no specific medicines are flagged for altering the exposure (AUC/Cmax) of Phloroglucinol. Furthermore, no specific warnings are mandated concerning interactions with food, alcohol, herbal products, or dietary supplements, and there are no documented mandatory timing-separation requirements for administration.

Mechanism of Action

The mechanism of action for Phloroglucinol involves direct modulation of smooth muscle contractility in visceral organs. This process is independent of the nervous system, focusing instead on internal cellular signaling.

Phloroglucinol targets the membrane of the smooth muscle cell, where it acts as an inhibitor and blocker of Voltage-Dependent L-Type Calcium Channels (CaV1.2). These channels are the primary gateway for extracellular calcium ions ( Ca^2+) to enter the cell. By limiting this influx, the drug directly modulates the electrical excitability of the muscle fiber, resulting in a reduction of smooth muscle excitability and contraction amplitude.

The reduction of calcium within the cell alters the downstream Excitation-Contraction Coupling Pathway. Insufficient Ca^2+ prevents the necessary activation of the enzyme Myosin Light Chain Kinase (MLCK), subsequently blocking the physical interaction between the muscle proteins (Actin and Myosin). The physiological consequence of this interference is spasmolysis, which is the direct relaxation of smooth muscle tone.

In some formulations, the derivative trimethylphloroglucinol is present, possessing a similar musculotropic action that complements the primary mechanism. However, this action is subject to antagonism by the spasmogenic effects of certain opioid analgesics, constraining the overall modulation of smooth muscle tone.

Dosage and Administration Information

Official Administration Routes and Forms

Phloroglucinol is administered through several officially approved routes, including oral use (tablets), parenteral injection (intravenous or intramuscular solution), and rectal use (suppositories). The selection of the route is defined by the clinical context, with the injection form typically used in acute care and the oral form used for follow-up or general symptomatic use.

Dosing and Frequency Guidelines

Usage of Phloroglucinol is characterized as symptomatic treatment, meaning the doses are taken only when symptoms occur, not on a routine, scheduled basis. The dosing and frequency limits established for this medication are as follows:

Patient Group Standard Dose Maximum Daily Limit Minimum Interval
Adults (Oral) 160 mg (two 80 mg tablets) 480 mg (six 80 mg tablets) 2 hours between doses
Children over 2 years (Oral) 80 mg (one 80 mg tablet) 160 mg (two 80 mg tablets) 2 hours between doses

Preparation and Procedural Rules

For oral tablets, specific instructions are provided for proper administration. Adults may take the tablet by dissolving it under the tongue for a potentially faster effect, or by dissolving it in a glass of water. For children over two years, the tablet must be dissolved in a glass of water before being consumed immediately. Use is not established for children under two years of age. Treatment duration is determined by the underlying condition, and users are instructed to seek reassessment if symptoms persist.

Recent Clinical Evidence

Recent Clinical Evidence Overview

Phloroglucinol is a phenol derivative commonly used for its non-specific antispasmodic properties, which primarily affect smooth muscle. Recent clinical research has focused on evaluating its effect in conditions involving spasms and motility issues, including gastrointestinal disorders, urological pain, and applications in obstetrics.

Gastrointestinal and Diagnostic Use

Studies have investigated phloroglucinol's role in managing symptoms of Irritable Bowel Syndrome (IBS), specifically the diarrhea-predominant type (IBS-D). A randomized, double-blind, placebo-controlled trial examining overall IBS symptoms reported that the proportion of patients responding positively was significantly higher in the phloroglucinol group compared to the placebo group after a three-week period (61.6% vs 30.6%).

Phloroglucinol has also been studied as a premedication for diagnostic procedures. Research has shown that oral administration of phloroglucinol significantly suppressed gastrointestinal peristalsis during unsedated esophagogastroduodenoscopy (EGD) compared with placebo, which improved the ease of intragastric observation for clinicians.

Spasms in Urinary and Biliary Tracts

Phase 3 multicenter, open-label, randomized studies have compared phloroglucinol preparations (oral and parenteral) against reference drugs for reducing pain and spasms associated with renal or biliary colic. These studies found that phloroglucinol was comparable to established current therapeutic options in providing relief from these spasms. Additionally, studies have explored phloroglucinol's potential application to assist in the shortening of the active phase of labor in pregnant women.

How should Phloroglucinol be stored and disposed of?

How to Store and Dispose of Phloroglucinol

The storage and disposal of Phloroglucinol must strictly follow regulatory documentation to maintain its quality and ensure environmental safety.

Storage Requirements

Phloroglucinol must be stored at a temperature below 30 C and out of the sight and reach of children. The medicine should be protected from moisture by keeping it in the original package and ensuring containers are tightly closed.

  • Stability: Do not use the product after the expiry date. If supplied in a bottle, the contents must be used within 1 month after first opening.

Disposal Instructions

Expired or unused Phloroglucinol must not be thrown away via wastewater or household waste. Disposal should be managed by asking a pharmacist for the correct procedure, which adheres to local pharmaceutical waste regulations.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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