Aromatic compounds

Basic characteristics and phenol

All pharmacological agents of this group share a common structural feature: the presence of a benzene ring. The main reference representative of the class is phenol (also known in medical practice as carbolic acid). All other considered drugs are classified either as its derivatives or as complex multicomponent products containing phenol as the active substance.

The spectrum of antimicrobial action of phenol has clear boundaries: it exerts a strong lethal effect on vegetative forms of microorganisms, yet demonstrates weak efficacy against bacterial spores. In modern medicine, the use of pure phenol is strictly limited. It is used exclusively for the disinfection of external environment objects. It is employed to treat medical instruments, hospital linens, room surfaces, and various household items. At the same time, phenol retains its significance as an active component in complex products such as tars and ichthammol.

Products of natural raw material distillation

This category includes complex mixtures obtained by thermal distillation.

1. Birch tar. By origin, this is a product of the distillation of birch bark. It possesses a triple pharmacological effect: antimicrobial, insecticidal (effective as a pediculicide), and locally irritant. The main indications for its prescription are various dermatological pathologies, such as eczema, psoriasis, and neurodermatitis. In clinical practice, tar is most often used not in its pure form, but as part of well-known combination drugs, for example, Wilkinson's ointment and Vishnevsky balsam liniment.

1. Ichthammol (ichthyo.). Unlike tar, ichthammol is a product of shale distillation. Its pharmacological profile is broader and includes antimicrobial, antiseptic, pronounced anti-inflammatory, keratoplastic, and local anesthetic effects. Methods of application depend on the medical field:
2. In dermatology, ichthammol is used in the form of ointments and pastes for the treatment of burns, erysipelas, and eczema.
3. In gynecology and proctology, the drug is prescribed in the form of suppositories for inflammatory processes of the pelvic organs, including diseases of the rectum and female genital organs.

Synthetic phenol derivatives

Chemically modified aromatic compounds include resorcinol and triclosan.

Resorcinol in its chemical structure is m-dihydroxybenzene. The mechanism of its antimicrobial action lies in the ability to cause protein coagulation, which directly leads to the death of vegetative microbial forms. The drug is indicated for bacterial and fungal skin lesions, including eczema, seborrhea, and conditions accompanied by severe pruritus.

Triclosan is a chlorine-containing phenol derivative characterized by extremely high antibacterial activity. Its mechanism of action differs fundamentally from resorcinol: triclosan inhibits lipid biosynthesis in the bacterial cell. A specific target for the drug is the enoyl-reductase enzyme encoded by the fabl gene. It is important to note that upon mutation of the fabl gene in microorganisms, resistance to triclosan may develop.

Areas of application for triclosan include:

• Surgical practice: antiseptic treatment of the surgeon's hands, preparation of the operative field, and wound treatment.
• Material production: incorporation into specialized medical plastics.
• Daily hygiene: use as an active component in toothpastes (e.g., Macleans), antibacterial soaps (e.g., Safeguard), and therapeutic shampoos.

Class and exam questions

What else to study on this topic

• Composition and features of application of Wilkinson's ointment and Vishnevsky liniment.
• Mechanisms of development of microbial resistance to chlorine-containing phenol derivatives.
• Comparative characteristics of the keratoplastic and locally irritant effects of the drugs.
• Use of ichthammol suppositories in gynecological and proctological practice.

Other topics in the section «Antiseptics and Disinfectants»

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