Optimizing Injection Route

Transcription

1 Gayle A. Brazeau, Ph.D. Pain Upon Injection: Fundamentals of Subcutaneous Anatomy and Physiology for Pharmaceutical Scientists Tuesday May 17, :00 am Three Key Considerations: Anatomy/Physiology Subcutaneous Tissues and Adjacent Tissues Mechanisms Pain and Pain Pathways Optimizing Vehicles and Excipients for Parenteral Formulations for Subcutaneous Injections.

2 Optimizing Injection Route J.F Jin, The optimal choice of medication administration route regarding intravenous, intramuscular, and subcutaneous injection, Patient Preference and Adherence 5: , 2015

3 Subcutaneous Tissue Space beneath the epidermis/dermis and skeletal muscle Also called hypodermis Lowermost layer of the integumentary system Composed of fibroblasts, adipose cells and microphages dia/file:skin.png

4

5 Injection Site Reactions

6 Key Questions What is the physiology associated with pain upon injection? What are the mechanisms associated with tissue damage? What is the role of inflammation and swelling/edema?

7 Pain and Injections Oh No, Not Again!

8 Nociceptors General Overview Sensory Receptors free (bare) nerve endings that detect signals from damaged tissue and indirectly respond to chemicals released from damaged tissue and or inflammation C-Fiber Classes and A Fiber Classes Categories Mechanical Thermal Chemical stimulation

9 Nociceptor - Types Mechanonociceptors respond to pinching, cutting or stretching Thermal nociceptors respond to the above stimuli and thermal stimuli Chemical nociceptors - respond only to chemical substances Polymodal nociceptors - respond to high intensity stimuli such as mechanical, thermal and to chemical substances

10 Tissue Damage and Injections

11 Factors Affecting Tissue Damage Lipophilicity vehicle/drug Concentration Osmolarity ph (SC Avoid below 3 and above 9) Particle Size Solubility and Precipitation Biochemical Mechanisms * Wu et al., JPP 62: 873, 2010

12 Biochemical Mechanisms: Tissue Site Reactions Disruption sarcolemma membrane Alteration in cellular homeostasis Calcium release and transport Cellular energetics Free Radical Damage

13 Tissue Damage and Nociceptors Inflammation Swelling/Edema Tissue Damage Nociceptor Activation Factors

14 Tissue Damage - Factors Activating Nociceptors Globulin and protein kinases Arachidonic acid Histamine Nerve growth factor (NGF) Substance P (SP) and calcitonin gene-related peptide (CGRP) Potassium - K + Serotonin (5-HT) Acetylcholine (ACh) Low ph (acidic) solution ATP Lactic acid

15 Formulation Considerations: Tissue Damage and Pain W. Wang, Tolerability of hypertonic injectables, International Journal of Pharmaceutics 490 (2015)

16 Important Considerations Avoid drugs or formulations which are irritating at the injection site Essential to initially screen for irritation Cell culture, isolated tissues (muscle, skin) Avoid drugs which may case vasoconstriction Avoid viscous suspensions All can lead to induration, sloughing, abscess formation or even necrosis

17 General Considerations SQ Sites Upper Arm Anterior Thigh Surface Lower Portion of Abdomen Upper Back Injection Volume 2-5 ml Needles 3/8 1 inch, Gauge

18 Drug Release Factors Function of drug solubility Type of formulation solution versus suspension Formulation viscosity Particle size Changes in blood flow (minor)

19 Formulation Factors - Tolerability Specific Agent/Concentration Formulation Excipients and ph Formulation Tonicity Formulation Osmolarity Injection Speed Injection Volume Injection Site Particle Size Injection Frequency

20 Molecule Dependent: Oligonucleotides Figure 2: All 21 sc administered ONs resulted in ISRs. Incidence ranged from 22 to 100%. For 4 ONs no incidence numbers were reported, namely IsisApo(a)Rx, Isis113715, ATL-03 and IsisGCGR-Rx. For ONs that were studies at different dose levels and/or multiple trials, an average ISR occurrence was calculated. Figure 3: Dose-dependent occurrence of ISRs after administration of four different ONs. Higher dose levels result in increased incidence of ISRs up to 100 % at the highest dose level. The dose levels tested for ISIS32566 and Mipomersen [10] were placebo (0), 50, 100, 200 and 400 mg. For IMO-8400 dose levels were: placebo (o), 0.075, 0.15, 0.3 and 0.6 mg/kg, and for ON_CHDR2 dose levels were placebo (0), 0.5, 1.5 and 5 mg/kg. L. van Meer et al. Injection Site Reactions after subcutaneous oligonucleotide therapy, doi: /bcp.12961

21 ph Effects

22 Local Tolerance of Subcutaneous Injections - Fransson & Espander Jansson, J. Pharm. Pharmacol., 1996 Non-physiological ph, buffer strength should be kept as low as possible to avoid pain on injection. Pain due to transport of K + causing depolarization of nerve endings. ph P NaCl VAS (mm) (mm) 6.0-A B C D E F* G* R * - with 5 mg/ml HIGF-1

23 Excipients: Buffers Goal Physiological ph (better to err on the more basic versus acidic) Most common: Citrate (5-15 mm), Higher concentration 50 mm can case pain (chelation of calcium) Acetates Lower ph (concern with lyophilization) Phosphates need to be cautious complexation Alternatives: lactate and tartrate Y. Mehmood, U. Farooq, Excipients Use in Parenteral and Lyophilized Formulation Development, Open Science Journal of Pharmacy and Pharmacology 3(3): 19-27, 2015

24 An In Vitro Muscle Model An isolated rodent extensor digitorum longus or soleus muscle 15 ml Test Solution Injected into the muscle or muscle incubated in the presence of the test compound Carbogenated 37 o C BSS Creatine kinase activity is measured with spectrophotometric kinetic assay at 340 nm

25 ph and Buffers* Carboxylic Buffers Acetate Succinate Citrate Type of Buffer ph Effect ph 2, 4, 6 Buffer Capacity 0.1, 0.01, *Napaporn et al., PDT, 2000

26 General Formulation Considerations 1. Buffer solutions with low concentrations should be made isotonic. 2. For acetate buffer, formulate a solution at low buffer capacity and near physiological ph. Although the myotoxicity of acetate buffers is not significantly different from normal saline, a trend towards increased myotoxicity was evident at higher buffer capacity and lower ph. 3. For succinate and citrate buffers, formulate near physiological muscle ph as the myotoxicity is minimized in this range.

27 Tonicity/Osmolarity Consequences: Enhanced tissue site irritation and pain, tissue permeability and possible damage For intradermal, subcutaneous, and intramuscular injections Ideally around mosm/kg Preferably < 600 mosm/kg Mitigation Avoid extreme ph and high buffer concentration Reduce injection volume Use anesthetic agent W. Wang, Tolerability of hypertonic injectables, International Journal of Pharmaceutics 490 (2015)

28 Injection Speed/Volume 82 Individuals Type 1 or 2 Diabetes, 39% Females SC injections in the abdomen or thigh of 0.9% sodium chloride Injection speeds: 150, 300 and 450 µl/s Volumes: 400, 800, 1200 and 1600 µl Pain; Visual Analogue scale (VAS) Results: Lower end of the VAS scale Speed of injection was not significant Larger injection volumes (1200 and 1600 µl) were associated with greater pain More pain associated with injections into thigh versus abdomen Heise et al., Impact of injection speed and volume on perceived pain during subcutaneous injections into the abdomen and thigh: a single-centre, randomized controlled trial, Diabetes, Obesity and Metabolism 16: , 2014

29 Viscosity, Injection Volume and Flow Normal Saline with nonanimal hyaluronic acid injections into the abdomen 24 subjects, 122 injections 6 injections per individual 22 technical incidents in 12 subjects Equal number of males/females C. Berteau et al., Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance, Med Devices (Auckl) 8: , 2015.

30 Fluid Depot Location Injected fluid location after injection (N=144). Notes: (A) Example of typical 2D-ultrasound B-mode echography of injection site in the abdomen, before (left) and after (right) injection in the same subject. The white arrow measures the injection depth. (B) Fluid location evaluated by echography images, percentage of fluid located exclusively in SC tissue. Significant difference (*P=0.0213) between 2 and 3 ml injections: fluid located exclusively in SC tissue more frequently with 3 ml injections. C. Berteau et al., Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance, Med Devices (Auckl) 8: , 2015.

31 Particle Size Tissue Damage Drug Suspension Concentration (%w/v) Bupivacaine 5% Phenytoin 10% Suspension Size Small Medium Large 0.2 m 1.2 m 4 m 6 m Classification pka Solubility Log P or clogp Local Anesthetic 8.05 Free Base Solubility: 0.7 mg/ml at ph 7.4 HCl Salt: 40 mg/ml 3.41 Anticonvulsant mg/ml 2.52 Diazepam 10% 0.4 m 1.7 m 2.1 m Anticonvulsant, sedative, and muscle relaxant 3.4 Free Base: 0.06 mg/ml

32 2000 Selective Suspensions 1500 Cumulative CK (Mean + SEM) * * * * * * * * 0 Normal Saline Bupivacaine (small) Bupivacaine (medium) Bupivacaine ( large) Diazepam (0.4 µm) Diazepam (1.7 µm) Diazepam (2.1 µm) Phenytoin (0.2 µm) Phenytoin (1.2 µm) Phenytoin (4.0 µm) Phenytoin (6.0 µm) Data was log transformed for statistical analysis. All treatments are significantly different from Normal Saline. (A) * p<0.05 versus Bupivacaine Small and Bupivacaine Medium.

33 Unmodified Polystyrene Beads Cumulative CK (Mean + SEM) U/L * * * # * # # * 0 Normal Saline 83nm 520nm µm µm Particle Size Data was log transformed. *p<0.05 versus Normal Saline. #p<0.05 versus Unmodified 83 nm particle size with n = 6-7.

34 Carboxyl Modified Polystyrene Beads 2100 Cumulative CK (Mean + SEM) U/L * * # # # * # * * 0 Normal Saline 104nm 424nm µm 3.06 µm Particle Size Data was log transformed. *p<0.05 versus Normal Saline. #p<0.05 versus Unmodified 83 nm particle size with n = 6-7.

35 Minimizing Injection Pain SQ Injections Medication should be at room temperature Warm the injection solution Let alcohol dry before injection Optimize injection depth Injection sites should be rotated Message the site after injection

36 Conclusions SQ Injection Formulations Complex site with potential for pain and/or tissue damage Ideally goal is to minimize the concentration of API, excipients, injection volume, ph, tonicity and viscosity needed for formulation stability and release Look at the pharmacological properties of the API or excipients which could cause pain or tissue damage Screen early in the development process for potential pain or tissue damage.

37 Questions

38 Thank You! Gayle Brazeau University of New England College of Pharmacy