Topical Pain Medications also know as Compounded pain creams
Topical Pain Creams compounded for topical use are gaining popularity for the management of chronic and acute pain. The advantages of topical pain medications include reduction of systemic adverse effects, improved patient acceptance, few drug interactions, ease of dose determination, avoidance of the first-pass metabolism, increased medication compliance, ease of administration. The ability of topical pain creams to directly access the target site, allow 70% delivery of medication the site of pain as opposed to 17% by the oral route. Compounded topical pain creams typically use a mixture of 3 or more single medications to achieve multiple complementary effects at lower doses of each individual medication. Herein, we review the mechanisms, adverse effects, and evidence for some of the most commonly used medications in topical pain creams for pain management. Because more topical pain creams are used for chronic pain, dermatologists can expect an increase in irritant and allergic contact dermatitis related to these medications. A new pain study confirms 45% reduction of opioid usage by using transdermal pain creams.
- A brief overview of the categories of pain
- Review opioid pharmacology
- Review the available treatment modalities and alternative options for pain management
- Art and science of preparing customized medications
- Today an estimated 10% of all prescriptions and medication orders are compounded
- Pain is an unpleasant sensory and emotional experience
- Every individual is unique and the pain experience can be equally diverse
- 1.5 billion people worldwide suffer from chronic pain
- 3-4.5% of the global population suffers from neuropathic pain incidence rate increases with age1
- Back pain is the leading cause of disability in Americans under 45 years old2
- More than 26 million Americans between the ages of 20-64 experience frequent back pain2
Special Feature: Pain.
The incidence of Pain – American Academy of Pain Medicine
Chronic Pain 100 million Americans Institute of Medicine of The National Academies 3
Diabetes 25.8 million Americans (diagnosed and estimated undiagnosed) American Diabetes Association
CHD (heart attack and chest pain) 16.3 million Americans American Heart Association
Stroke 7.0 million Americans
Cancer 11.9 million Americans American Cancer Society
5 Major Categories of Pain
- Inflammatory – response to tissue damage that potentiates pain
- Pro-inflammatory mediators → peripheral sensitization
- Phenotypic switch (chemical and physical change in character and function of nerves – neuroplastic change)
- Central sensitization
- Soft tissue – pressure ulcers, burns
- Intracranial pressure – brain tumor edema and hemorrhage
- Nociceptive – CNS and peripheral afferent pathways modulated via the spinal cord
- Somatic – aching, constant, localized (musculoskeletal)
- Visceral – sharp, crescendo/decrescendo (cholecystitis, renal stones, intestinal obstruction, MI)
- Neuropathic – ischemia, destruction or encroachment of nerve by disease or tumor
- Paroxysmal shooting or shock-like pain on a background of burning, aching sensation
Receptor Affinity of Opioid Analgesics
- Opioid: Narcotic or opiate-like drugs include natural, synthetic, and endogenous ligands/substances
- Receptor site: that portion of a nerve cell to which a drug can bind. There are several opioid receptor sites, e.g., mu (beta-endorphins), kappa (dynorphins) and delta (met- & leu-enkephalins)
- Agonist: in large enough doses, this type of drug binds to a specific site and initiates activity at that receptor site.
- Types of agonist:
- Pure agonist – binds tightly with the receptor site and produces the near maximal activity possible at that receptor site.
- Partial agonist – binds with the receptor site less tightly than a pure agonist
- Antagonist: in large enough doses, this type of drug binds to a specific site, or it displaces the agonist at the receptor site, thereby stopping the receptor’s activity.
- Types of antagonist:
- Pure antagonist – binds tightly with the receptor site and stops or blocks activity at that receptor site.
- Partial antagonist – binds with the receptor site less tightly than a pure antagonist, stopping or blocking less of the activity at that receptor site
N-Methyl D-Aspartate Antagonist/Inhibitors
NMDA N-methyl-D-aspartate receptor Antagonists
- Blocks the amino acid glutamate from binding to NMDA receptors
- reducing the depolarization of spinal cord neurons
- continued firing of these neurons causes hyperalgesia
- This increased response or hypersensitivity to a painful stimulus causes a “windup” phenomenon, a progressive increase in depolarization spikes that cause a single summation spike and the spontaneous firing of neurons that can persist for minutes
Transdermal Treatment with Topical Pain Creams
- Transdermal delivery allows drugs to solubilize in order to penetrate the tissue layers
- Gels form liposomes that carry the drug down between the cells of the dermis and epidermis.
- Minimizes SE’s by delivering the drug to the site of injury.
- Research confirms peripheral site of action for many of these drugs.
Common Topical Pain Cream Agents
Mode of Action of Topical Pain Creams
NMDA receptor antagonist, advantageous because it is not a controlled substance.
Has been shown to reduce nerve pain when used topically but the mechanism of action is unknown.
Very effective muscle relaxant and anti-spastic agent. Thought to work by decreasing excitatory neurotransmitter release.
Local anesthetic with double the duration of action of Lidocaine. Sodium channel blocker that works to prevent ectopic neuropathic impulses.
Effective for treating trigeminal neuralgia. Decreases polysynaptic responses and blocks post-tetanic potentiation. Great for relieving nerve pain.
An alpha receptor agonist useful in reducing neuropathic pain, especially syndromes with a sympathetic component.
Muscle relaxant and an anti-spastic agent that affects muscle function. Possesses anti- neuropathic properties as it is structurally related to the tricyclic antidepressants by inhibiting sodium channels.
A natural anti-viral from Alaskan Red Algae.
A potent NSAID with augmented absorption and depot effect.
Anticonvulsant which works by 3 mechanisms for neuropathic pain. Best combined with ketamine for a maximum synergistic effect.
Has been shown in studies to be an effective muscle relaxant but the mechanism of action is unclear.
Inhibiting cyclooxygenase and preventing formation of inflammatory mediators, such as prostacyclin, prostaglandin, and thromboxane, NSAID. Best for pain involving torn muscles and similar injuries.
An opioid agonist that produces an antihyperalgesic effect through peripheral opioid receptors in inflamed tissue.
A mineral is known for its ability to provide muscle relaxation.
Calcium channel blocker that works at the gated NMDA receptor but also greatly improves tissue perfusion, improving healing time and nerve conduction velocity.
Strong muscle relaxant and pain relieving agent that provides both NMDA receptor and sodium channel blocking properties. Provides additional benefits when combined with neuropathic and muscle relaxing agents.
A xanthine derivative that improves blood flow in peripheral extremities.
An anticonvulsant used in combo with other analgesics for chronic pain.
Member of the oxicam family, inhibits edema, erythema,
tissue proliferation, fever, and pain.
An anticonvulsant with numerous properties contributing to pain relief.
Used topically as an analgesic and an antipyretic that replaces the perception of musculoskeletal pain with a cooling sensation.
Acts as a local anesthetic or counterirritant by replacing the perception of localized pain with a cooling sensation.
Dimethyl sulfoxide used to increase skin penetration
Some of the Numerous Clinical Trials of Topical Pain Creams
- BAK-Baclofen 1.67%, Amitriptyline 3.33%, Ketamine 1.67% (5ml twice daily)
- Chemotherapy-induced peripheral neuropathy
- Locally we see BAK 2/2/2%, max 5/5/5%
- Sig: Apply 1-2 ml topically up to tid
- AK-Amitriptyline 4%/ Ketamine 2%
- Sig: 4ml topically bid
- amitriptyline 40mg/ml, ketamine 20mg/ml
- Clinicaltrials.gov identifier: nct00516503
Topical Pain Creams for Neuropathic Pain
Visible role in treating neuropathic pain Pain Med. 2000 Mar;1(1):97-100.