What are the functions, uses, and common preparations of medicinal camphor as a pharmaceutical-grade active pharmaceutical ingredient?

Pharmacopoeia quality standards for pharmaceutical-grade camphor:

- Description: White crystalline powder or colorless, translucent hard lumps. When a small amount of ethanol is added, it is easily ground into fine powder; it has a characteristic pungent odor and an initially pungent taste followed by a cooling sensation. It is highly volatile at room temperature and burns with a smoky, luminous flame. It is readily soluble in ethanol, fatty oils, or volatile oils, and very slightly soluble in water.

- Melting point: 176–181°C.

- Specific optical rotation: Dissolve a precisely weighed sample in ethanol and quantitatively dilute to prepare a solution containing about 0.1g per 1ml. The specific optical rotation is between +41° and +44°.

- Identification: Dissolve the sample in ethanol and dilute to prepare a solution containing about 2.5mg per 1ml. Measure the absorbance using ultraviolet-visible spectrophotometry in the wavelength range of 230–350nm. Maximum absorption occurs at 289nm with an absorbance of approximately 0.53. Additionally, the infrared absorption spectrum of the sample should match the reference spectrum (Spectrum Collection, Figure 535).

What are the functions, uses, and common preparations of medicinal camphor as a pharmaceutical-grade active pharmaceutical ingredient?

Common camphor preparations are mainly divided into topical and oral formulations based on their dosage forms and uses. Below is a detailed introduction:

I. Topical Preparations of Medicinal Camphor

1. Camphor Ointment  

- Ingredients: Primarily contains camphor, often combined with bases such as petroleum jelly.  

- Function: Stimulates vasodilation of skin blood vessels, improves local blood circulation, relieves muscle soreness and joint pain, and can also be used to alleviate itching and reduce swelling in the early stages of frostbite.  

- Applicable scenarios: Suitable for rheumatoid arthritis, muscle strain, frostbite (when unbroken), etc.  

2. Camphor Spirit (Camphor Alcohol Solution)  

- Ingredients: A solution of camphor dissolved in ethanol (typically at a concentration of 10%).  

- Function: When applied to the skin, the evaporation of ethanol cools the area, while camphor stimulates cold receptors, producing a cooling sensation that provides analgesic and antipruritic effects. It also has some antibacterial properties.  

- Applicable scenarios: Used for insect bite dermatitis, skin itching, neurodermatitis, etc. It can also be applied as a topical liniment to relieve muscle soreness.  

3. Compound Camphor Cream  

- Ingredients: Camphor combined with menthol, methyl salicylate, diphenhydramine, and other components.  

- Function: Provides comprehensive analgesic, antipruritic, anti-inflammatory, and antihistamine effects, alleviating both local pain and itching caused by allergies.  

- Applicable scenarios: Used for skin conditions such as eczema, allergic dermatitis, insect bite dermatitis, and neurodermatitis.  

4. Camphor Liniment  

- Ingredients: A mixture of camphor with alcohol, glycerol, etc.  

- Function: Stimulates local blood circulation to relieve joint and muscle pain. Glycerol helps keep the skin moist and reduces irritation from alcohol.  

- Applicable scenarios: Often used as an adjunct treatment for rheumatoid arthritis, muscle pain, frostbite, etc.  

II. Oral Preparations of Medicinal Camphor

1. Sodium Camphorsulfonate Injection (for injection)  

- Ingredients: Sodium camphorsulfonate, a colorless or slightly yellow clear liquid.  

- Function: In small doses, it stimulates the medullary respiratory and vasomotor centers. In larger doses, it excites the cerebral cortex, improving respiratory and circulatory functions.  

- Applicable scenarios: Used to treat central respiratory and circulatory insufficiency, respiratory depression caused by drowning or poisoning. It must be administered intravenously or intramuscularly under medical supervision.  

2. Camphor Tincture (oral preparation, less common)  

- Ingredients: An ethanol solution of camphor (low concentration), prepared according to pharmacopoeial standards.  

- Function: When taken orally, it stimulates the gastric mucosa, reflexively exciting the central nervous system. It also has mild carminative and expectorant effects.  

- Applicable scenarios: Previously used to treat gastrointestinal flatulence, motion sickness, and seasickness. However, due to camphor's toxicity and side effects, it is now rarely used clinically, and dosage must be strictly controlled.  

III. Other Preparations of Medicinal Camphor (Traditional Chinese Medicine or Compound Formulations)

1. Bingpeng Powder (contains camphor)  

- Ingredients: Borneol, borax, cinnabar, camphor, etc. (a traditional Chinese medicine compound).  

- Function: Clears heat, detoxifies, reduces swelling, and relieves pain. Camphor contributes by inducing resuscitation and alleviating pain.  

- Applicable scenarios: Used for sore throat, gum swelling and pain, mouth and tongue sores, etc.  

2. Essential Balm (contains camphor)  

- Ingredients: Menthol, camphor, eucalyptus oil, eugenol, etc.  

- Function: Provides cooling, pain relief, wind-dispelling, and antipruritic effects. Camphor enhances analgesic and refreshing effects.  

- Applicable scenarios: Used for mosquito bites, motion sickness, headaches, dizziness, etc. It can be applied topically or taken orally in small amounts (follow instructions).