Polysulfated Glycosaminoglycan

Disease-modifying osteoarthritis agent (DMOA) Glycosaminoglycan

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog IM 5 mg/kg Twice weekly for up to 4 weeks Duration: 4 weeks; may repeat after 8 weeks
Notes: Administer by deep intramuscular injection. Do not mix with other drugs.
Horse IM 500 mg (approximately 1 mg/kg) Every 4 days for 7 treatments Duration: 28 days
Notes: Alternatively, 250 mg every 4 days for 7 treatments. For intra-articular use, 250 mg per joint once weekly for up to 5 weeks.
Horse IA 250 mg per joint Once weekly for up to 5 weeks Duration: 5 weeks
Notes: Strict aseptic technique required. Do not use if joint infection is suspected.

Clinical Indications & Species Uses

General Indications
  • Symptomatic treatment of osteoarthritis and joint inflammation in companion animals
Dog (Canine)
  • Treatment of non-infectious degenerative and traumatic arthritis
  • Management of osteoarthritis
  • Improvement of joint function and lameness
Horse (Equine)
  • Treatment of degenerative joint disease (osteoarthritis)
  • Traumatic arthritis
  • Acute and chronic lameness associated with joint inflammation

Pharmacology & Mechanism of Action

Drug Class: Disease-modifying osteoarthritis agent (DMOA) | Pharmacological Group: Glycosaminoglycan

Mechanism of Action: Polysulfated glycosaminoglycan (PSGAG) is a semi-synthetic glycosaminoglycan derived from bovine tracheal cartilage. It exerts its effects by inhibiting enzymes that degrade cartilage matrix, such as metalloproteinases (e.g., collagenase, stromelysin) and aggrecanases, and by reducing the activity of inflammatory mediators like prostaglandins and interleukins. PSGAG also stimulates the synthesis of cartilage matrix components, including proteoglycans and collagen, and enhances the production of hyaluronic acid in synovial fluid. It may also inhibit the complement system and reduce the chemotaxis of leukocytes, thereby decreasing joint inflammation and slowing the progression of osteoarthritis.

Pharmacodynamics: PSGAG has a high affinity for cartilage and synovial tissue, where it accumulates and exerts its chondroprotective effects. It reduces the degradation of cartilage proteoglycans and collagen, promotes the synthesis of new matrix components, and improves the viscoelastic properties of synovial fluid. In clinical studies, PSGAG has been shown to improve joint function, reduce lameness, and slow the radiographic progression of osteoarthritis in horses and dogs. Its effects are typically seen after several weeks of treatment and may persist for weeks to months after discontinuation.

⚡ Pharmacokinetics Summary

Absorption: After intramuscular (IM) or subcutaneous (SC) administration, PSGAG is absorbed into the systemic circulation. Bioavailability is high after IM injection, with peak plasma concentrations occurring within 1-2 hours. Oral absorption is poor and not clinically used.
Distribution: PSGAG distributes widely into synovial fluid and cartilage, where it binds to proteoglycans and collagen. It has a high affinity for articular cartilage and synovial membrane, with concentrations in these tissues exceeding plasma levels. It also distributes to other connective tissues.
Metabolism: PSGAG is metabolized in the liver and possibly in the synovium. It undergoes desulfation and depolymerization to smaller fragments, which are then excreted.
Excretion: PSGAG and its metabolites are primarily excreted via the kidneys. In horses, approximately 50% of an administered dose is excreted in urine within 24 hours, with the remainder excreted over several days.
Half-Life: The elimination half-life in horses is approximately 2-3 hours for the parent compound, but the pharmacological effect persists much longer due to tissue binding. In dogs, the half-life is similar.
Bioavailability: Intramuscular and subcutaneous administration results in high bioavailability (nearly 100%). Oral bioavailability is negligible.
Protein Binding: PSGAG is highly protein-bound, with approximately 90% bound to plasma proteins.

Available Formulations & Strengths

Injectable Solution 100 mg/mL (5 mL vial) (IM, IA)

Contraindications & Clinical Warnings

Contraindications:
  • Known hypersensitivity to PSGAG or any component
  • Active joint infection (septic arthritis) – especially for intra-articular use
  • Bleeding disorders or concurrent anticoagulant therapy (due to potential anticoagulant effects)
  • Pregnancy or lactation (safety not established)
Warnings & Clinical Precautions:
  • Use with caution in animals with hepatic or renal impairment
  • Intra-articular injections must be performed under strict aseptic conditions
  • Do not administer intravenously
  • May cause transient pain or swelling at injection site
  • Not for use in food animals due to lack of withdrawal time data
  • Safety in breeding, pregnant, or lactating animals has not been established

Adverse Effects & Reactions

Common:

  • Injection site pain or swelling
  • Transient lameness after intra-articular injection

Serious / Severe:

  • Anaphylactic reactions (rare)
  • Coagulopathy (with high doses or concurrent anticoagulant use)

Rare:

  • Allergic reactions
  • Hepatotoxicity (reported in some cases)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Anticoagulants (e.g., warfarin, heparin) PSGAG may have anticoagulant properties and may increase the risk of bleeding when used with anticoagulants. High
Nonsteroidal anti-inflammatory drugs (NSAIDs) Concurrent use may increase the risk of gastrointestinal ulceration and renal toxicity, although PSGAG is often used with NSAIDs for synergistic effects. Moderate
Corticosteroids Concurrent use may reduce the chondroprotective effects of PSGAG; avoid intra-articular injection of corticosteroids with PSGAG. Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Gastrointestinal upset (vomiting, diarrhea)
  • Incoordination
  • Bleeding tendencies
  • Hypotension

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Monitor for bleeding and administer fresh frozen plasma or vitamin K if coagulopathy occurs. Provide fluid therapy and supportive care as needed.

Food Animal Withdrawal Times

Not approved for use in food animals; no withdrawal times established. Do not use in animals intended for human consumption.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F)

Handling & Special Conditions: Protect from freezing. Keep out of reach of children.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs and horses (e.g., Adequan® Canine and Adequan® i.m. for horses).

Extra-Label (Off-Label) Use: In the US, PSGAG is approved for use in dogs and horses. Extra-label use in other species is permitted under AMDUCA only with a valid veterinarian-client-patient relationship and appropriate withdrawal times.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Polysulfated glycosaminoglycan is a valuable disease-modifying agent for the management of osteoarthritis in dogs and horses. It is most effective when used early in the disease process and may be combined with NSAIDs, physical therapy, and weight management. Intra-articular administration should be reserved for cases where systemic therapy is ineffective or for targeted joint treatment. Response to therapy may take several weeks; a re-evaluation is recommended after the initial course. Adverse effects are uncommon but include injection site reactions and rare allergic reactions. Use with caution in animals with bleeding disorders or those on anticoagulant therapy. Not for use in food animals.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)