Be gentle & firm.
Place your cat on a table or bench.
Have the other adult hold each of the cat's elbows so that they are locked straight while tucking the cat's body against theirs. Or wrap the cat in a large towel so only the head is visible.
Have the adult lean on the cat to keep him against the table.
Try to wear a sweater or shirt so if the cat tries to scratch with the back feet it can't do too much damage.
Step#2: Giving Pills
Try a pill syringe. These are available at most pet-supply stores. Be sure to ask your vet to demonstrate them, so that you do not hurt kitty. If you are unable to find one, here it goes:
Hold the head in the palm of your hand and gently tilt the cat's head back (cats reflexively relax their jaw and open their mouth slightly). Hold the pill in the opposite hand between your thumb and index finger With your middle or ring finger, gentle lever the jaw open and place the pill onto the back of the tongue.
Push the tablet over the back of the tongue with a finger.
Quickly close the mouth and rub the throat to stimulate swallowing. Blowing on your cat's nose tends to give it a bit of a fright and may induce it to swallow.
or Liquid Medicine
Restrain your cat as above.
Hold the cat's head this time holding both top and bottom jaw. Tilt the cat's nose slightly upwards.
Using an eye dropper/syringe slowly place the medication into your cat's mouth.
The tip of the dropper can be inserted st behind the canine (fang or eye) tooth where the jaw does not completely close.
Unless the dose is small give the medication slowly allowing your cat to swallow and to lick the medication from its mouth before giving more.
Rubbing the throat or blowing on your cat's nose may help to stimulate swallowing.
Never inject into the back of the mouth as this may cause your cat to choke
Always give your cat positive attention following successful medication.
Praise him, play with him, and if approved by your veterinarian, offer a tasty food reward so the next time will go even more smoothly.